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  • Duplicate entries on mysql on insert using doctrine

    - by Nikos Galis
    Hi all! I am facing a very weird problem with mysql and doctrine [with help of codeIgniter]. I am trying to make a simple migration script taking all records from one table and after a little process, saving them to another. However, on my laptop [running windows and wamp] I get double numbers of the original table records to have been copied to the destination table. In my colleagues' laptops, everything works fine! We are all using mysql 5.0.86 [plus windows plus wamp]. Here is the code : function buggy_function(){ $this->db(); //get db connection $q = Doctrine_Query::create()->from('Oldtable r'); $oldrecords = $q->fetchArray(); $count = 0; foreach ($oldrecords as $oldrecord){ $newrecord = new NewTableClass(); $newrecord->password = md5($oldrecord['password']); $newrecord->save(); echo $newrecord->id. ' Id -> saved.' } } Simple as that! I have 39 records on the Old table and I am getting 78 records in the new table, which are exactly the same records, except from the unique primary key. It seems as if the script runs twice. But the output of the script is the following : 1 Id -> saved. 2 Id -> saved. ... ... 39 Id -> saved. Do you have any idea why this is happening? Any known bug for mysql? Thank you in advanced!'

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  • SQL (mySQL) update some value in all records processed by a select

    - by jdmuys
    I am using mySQL from their C API, but that shouldn't be relevant. My code must process records from a table that match some criteria, and then update the said records to flag them as processed. The lines in the table are modified/inserted/deleted by another process I don't control. I am afraid in the following, the UPDATE might flag some records erroneously since the set of records matching might have changed between step 1 and step 3. SELECT * FROM myTable WHERE <CONDITION>; # step 1 <iterate over the selected set of lines. This may take some time.> # step 2 UPDATE myTable SET processed=1 WHERE <CONDITION> # step 3 What's the smart way to ensure that the UPDATE updates all the lines processed, and only them? A transaction doesn't seem to fit the bill as it doesn't provide isolation of that sort: a recently modified record not in the originally selected set might still be targeted by the UPDATE statement. For the same reason, SELECT ... FOR UPDATE doesn't seem to help, though it sounds promising :-) The only way I can see is to use a temporary table to memorize the set of rows to be processed, doing something like: CREATE TEMPORARY TABLE workOrder (jobId INT(11)); INSERT INTO workOrder SELECT myID as jobId FROM myTable WHERE <CONDITION>; SELECT * FROM myTable WHERE myID IN (SELECT * FROM workOrder); <iterate over the selected set of lines. This may take some time.> UPDATE myTable SET processed=1 WHERE myID IN (SELECT * FROM workOrder); DROP TABLE workOrder; But this seems wasteful and not very efficient. Is there anything smarter? Many thanks from a SQL newbie.

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  • How can I get a distinct list of elements in a hierarchical query?

    - by RenderIn
    I have a database table, with people identified by a name, a job and a city. I have a second table that contains a hierarchical representation of every job in the company in every city. Suppose I have 3 people in the people table: [name(PK),title,city] Jim, Salesman, Houston Jane, Associate Marketer, Chicago Bill, Cashier, New York And I have thousands of job type/location combinations in the job table, a sample of which follow. You can see the hierarchical relationship since parent_title is a foreign key to title: [title,city,pay,parent_title] Salesman, Houston, $50000, CEO Cashier, Houston, $25000 CEO, USA, $1000000 Associate Marketer, Chicago, $75000 Senior Marketer, Chicago, $125000 ..... The problem I'm having is that my Person table is a composite key, so I don't know how to structure the start with part of my query so that it starts with each of the three jobs in the cities I specified. I can execute three separate queries to get what I want, but this doesn't scale well. e.g.: select * from jobs start with city = (select city from people where name = 'Bill') and title = (select title from people where name = 'Bill') connect by prior parent_title = title UNION select * from jobs start with city = (select city from people where name = 'Jim') and title = (select title from people where name = 'Jim') connect by prior parent_title = title UNION select * from jobs start with city = (select city from people where name = 'Jane') and title = (select title from people where name = 'Jane') connect by prior parent_title = title How else can I get a distinct list (or I could wrap it with a distinct if not possible) of all the jobs which are above the three people I specified?

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  • Best practice to pass a value from pop over control on iPad.

    - by Tattat
    It is an iPad app based on SDK 3.2. I have a MainUIView, that is subclass from UIView, it have a UIButton and a UILabel. When user press the UIButton, the pop over control will be appeared with a table view. When the user select a cell from the table view, the UILabel changes content base on the user click, and the pop up table view will disappear. The question is, how can I pass the "selected cell" to the UILabel. I am thinking making a "middle man" object. When the user click the UIButton, and the "middle man" will pass to the table. When the cell is selected, the "middle man" will store the idx, and call the UILabel change content from the value of "middle man". But I think it is pretty complex to implement, is there any easier way to implement it? thz u.

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  • [Newbie] How to join mysql tables

    - by Ivan
    I've an old table like this: user> id | name | address | comments And now I've to create an "alias" table to allow some users to have an alias name for some reasons. I've created a new table 'user_alias' like this: user_alias> name | user But now I have a problem due my poor SQL level... How to join both tables to generate something like this: 1 | my_name | my_address | my_comments 1 | my_alias | my_address | my_comments 2 | other_name | other_address | other_comments I mean, I want to make a "SELECT..." query that returns in the same format as the "user" table ALL users and ALL alias.. Something like this: SELECT user.* FROM user LEFT JOIN user_alias ON `user`=`id` but it doesn't work for me..

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  • Selenium Testing

    - by Joakim
    Hi I want to get a bunch of dom-objects with xpath and loop through those to check if they contains a specified text, is this possible in the Selenium IDE or rc? Perl is my prefered language XPath would be something like xpath=//tbody[@class='table-data']/tr/td/div[@class='table-item'] This would return all row items in the table, but i need to check each div if contains a specified text string. Is this possible with Selenium? Best regards

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  • MS SQL share identitiy seed amongst tables

    - by Net Citizen
    In MS SQL is it possible to share an identity seed across tables? For example I may have 2 tables: Table: PeopleA id name Table: PeopleB id name I'd like for PeopleA.id and PeopleB.id to always have unique values between themselves. I.e. I want them to share the same Identity seed. Note: I do not want to hear about table partitioning please, only about if it's possible to share a seed across tables.

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  • Django version in GAE

    - by Alex
    I'm tring to use Django 1.1 in GAE, But when I uncomment use_library('django', '1.1') in this script import os os.environ['DJANGO_SETTINGS_MODULE'] = 'settings' from google.appengine.dist import use_library #use_library('django', '1.1') # Google App Engine imports. from google.appengine.ext.webapp import util # Force Django to reload its settings. from django.conf import settings settings._target = None import django.core.handlers.wsgi import django.core.signals import django.db import django.dispatch.dispatcher # Unregister the rollback event handler. django.dispatch.dispatcher.disconnect( django.db._rollback_on_exception, django.core.signals.got_request_exception) def main(): # Create a Django application for WSGI. application = django.core.handlers.wsgi.WSGIHandler() # Run the WSGI CGI handler with that application. util.run_wsgi_app(application) if __name__ == "__main__": main() I receives AttributeError: 'module' object has no attribute 'disconnect' What is going on?

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  • Mysql - Summary Tables

    - by jwzk
    Which method do you suggest and why? Creating a summary table and . . . 1) Updating the table as the action occurs in real time. 2) Running group by queries every 15 minutes to update the summary table. 3) Something else? The data must be near real time, it can't wait an hour, a day, etc.

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  • When I make a database change, how do I know what needs to be removed and readded to the LinqToSql O

    - by Michael Maddox
    For example, I alter a column in a table to be not null from null. I need to then delete and readd the table. That part is pretty clear. What about views, functions, and stored procedures that access the table, especially that column in the table? I've tried running diffs against the files generated by SQLMetal with some limited success, but even with that it's fairly unclear. I know there is at least one commercial tool out there that claims to address this problem, but I am looking for something free. How are people dealing with this issue?

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  • Strategy in exporting to Excel with formatting from ASP.NET?

    - by Jiho Han
    So this is another exporting to Excel question. I have a page that has a table with formatting by stylesheet. When I export the page by setting the ContentType to application/excel and Content-Disposition to attachment, I can export the table to Excel (not CSV). However, it loses all formatting. I think it's because Excel does not load CSS and I guess that's reasonable. So, in a scenario where I have to show the table on the web and also export to Excel, both with similar (even if not exact) formatting, what would be the best approach without using something like NPOI? I am trying to minimize the work and keep the single template if possible. Is it necessary for me to create two separate templates: one with stylesheet, the other with embedded style in the table itself for Excel? Having a single template with conditional formatting inside would be very messy. Any ideas?

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  • How to read a database record with a DataReader and add it to a DataTable

    - by Olga
    Hello I have some data in a Oracle database table(around 4 million records) which i want to transform and store in a MSSQL database using ADO.NET. So far i used (for much smaller tables) a DataAdapter to read the data out of the Oracle DataBase and add the DataTable to a DataSet for further processing. When i tried this with my huge table, there was a outofmemory exception thrown. ( I assume this is because i cannot load the whole table into my memory) :) Now i am looking for a good way to perform this extract/transfer/load, without storing the whole table in the memory. I would like to use a DataReader and read the single dataRecords in a DataTable. If there are about 100k rows in it, I would like to process them and clear the DataTable afterwards(to have free memory again). Now i would like to know how to add a single datarecord as a row to a dataTable with ado.net and how to completly clear the dataTable out of memory: My code so far: Dim dt As New DataTable Dim count As Int32 count = 0 ' reads data records from oracle database table' While rdr.Read() 'read n records and add them to a dataTable' While count < 10000 dt.Rows.Add(????) count = count + 1 End While 'transform data in the dataTable, and insert it to the destination' ' flush the dataTable after insertion' count = 0 End While Thank you very much for your response!

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  • Android: database reading problem throws exception

    - by Vamsi
    Hi, i am having this problem with the android database. I adopted the DBAdapter file the NotepadAdv3 example from the google android page. DBAdapter.java public class DBAdapter { private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "PasswordDb"; private static final String DATABASE_TABLE = "myuserdata"; private static final String DATABASE_USERKEY = "myuserkey"; private static final int DATABASE_VERSION = 2; public static final String KEY_USERKEY = "userkey"; public static final String KEY_TITLE = "title"; public static final String KEY_DATA = "data"; public static final String KEY_ROWID = "_id"; private final Context mContext; private DatabaseHelper mDbHelper; private SQLiteDatabase mDb; private static final String DB_CREATE_KEY = "create table " + DATABASE_USERKEY + " (" + "userkey text not null" +");"; private static final String DB_CREATE_DATA = "create table " + DATABASE_TABLE + " (" + "_id integer primary key autoincrement, " + "title text not null" + "data text" +");"; private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(DB_CREATE_KEY); db.execSQL(DB_CREATE_DATA); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS myuserkey"); db.execSQL("DROP TABLE IF EXISTS myuserdata"); onCreate(db); } } public DBAdapter(Context ctx) { this.mContext = ctx; } public DBAdapter Open() throws SQLException{ try { mDbHelper = new DatabaseHelper(mContext); } catch(Exception e){ Log.e(TAG, e.toString()); } mDb = mDbHelper.getWritableDatabase(); return this; } public void close(){ mDbHelper.close(); } public Long storeKey(String userKey){ ContentValues initialValues = new ContentValues(); initialValues.put(KEY_USERKEY, userKey); try { mDb.delete(DATABASE_USERKEY, "1=1", null); } catch(Exception e) { Log.e(TAG, e.toString()); } return mDb.insert(DATABASE_USERKEY, null, initialValues); } public String retrieveKey() { final Cursor c; try { c = mDb.query(DATABASE_USERKEY, new String[] { KEY_USERKEY}, null, null, null, null, null); }catch(Exception e){ Log.e(TAG, e.toString()); return ""; } if(c.moveToFirst()){ return c.getString(0); } else{ Log.d(TAG, "UserKey Empty"); } return ""; } //not including any function related to "myuserdata" table } Class1.java { mUserKey = mDbHelper.retrieveKey(); mDbHelper.storeKey(Key); } the error that i am receiving is from Log.e(TAG, e.toString()) in the methods retrieveKey() and storeKey() "no such table: myuserkey: , while compiling: SELECT userkey FROM myuserkey"

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  • SQL deadlock on delete then bulk insert

    - by StarLite
    I have an issue with a deadlock in SQL Server that I haven't been able to resolve. Basically I have a large number of concurrent connections (from many machines) that are executing transactions where they first delete a range of entries and then re-insert entries within the same range with a bulk insert. Essentially, the transaction looks like this BEGIN TRANSACTION T1 DELETE FROM [TableName] WITH( XLOCK HOLDLOCK ) WHERE [Id]=@Id AND [SubId]=@SubId INSERT BULK [TableName] ( [Id] Int , [SubId] Int , [Text] VarChar(max) COLLATE SQL_Latin1_General_CP1_CI_AS ) WITH(CHECK_CONSTRAINTS, FIRE_TRIGGERS) COMMIT TRANSACTION T1 The bulk insert only inserts items matching the Id and SubId of the deletion in the same transaction. Furthermore, these Id and SubId entries should never overlap. When I have enough concurrent transaction of this form, I start to see a significant number of deadlocks between these statements. I added the locking hints XLOCK HOLDLOCK to attempt to deal with the issue, but they don't seem to be helpling. The canonical deadlock graph for this error shows: Connection 1: Holds RangeX-X on PK_TableName Holds IX Page lock on the table Requesting X Page lock on the table Connection 2: Holds IX Page lock on the table Requests RangeX-X lock on the table What do I need to do in order to ensure that these deadlocks don't occur. I have been doing some reading on the RangeX-X locks and I'm not sure I fully understand what is going on with these. Do I have any options short of locking the entire table here?

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  • Can't locate in @inc during CPAN dependency install performed not as root.

    - by garrett
    While trying to do: perl -I'/v1/data/site_perl' -MCPAN -e 'install Log::Dispatch'; I continue to get "Can't locate Params/Validate.pm in @INC." When looking at the output, /v1/data/site_perl is NOT in the @INC displayed, even though I used -I. I am not root so I have changed my CPAN config so that: 'makepl_arg' => q[LIB=/v1/data/site_perl INSTALLSITEMAN1DIR=/v1/data/site_perl/man/man1 INSTALLSITEMAN3DIR=/v1/data/site_perl/man/man3 INSTALLMAN1DIR=/v1/data/site_perl/man/man1 INSTALLMAN3DIR=/v1/data/site_perl/man/man3] So even LIB is set. In a basic script I have: use lib '/v1/data/site_perl'; use Params::Validate; With no problems. How do I make the Log::Dispatch use lib /v1/data/site_perl without a force install? What am I missing?

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  • Need help with Xpath methods in javascript (selectSingleNode, selectNodes)

    - by Andrija
    I want to optimize my javascript but I ran into a bit of trouble. I'm using XSLT transformation and the basic idea is to get a part of the XML and subquery it so the calls are faster and less expensive. This is a part of the XML: <suite> <table id="spis" runat="client"> <rows> <row id="spis_1"> <dispatch>'2008', '288627'</dispatch> <data col="urGod"> <title>2008</title> <description>Ur. god.</description> </data> <data col="rbr"> <title>288627</title> <description>Rbr.</description> </data> ... </rows> </table> </suite> In the page, this is the javascript that works with this: // this is my global variable for getting the elements so I just get the most // I can in one call elemCollection = iDom3.Table.all["spis"].XML.DOM.selectNodes("/suite/table/rows/row").context; //then I have the method that uses this by getting the subresults from elemCollection //rest of the method isn't interesting, only the selectNodes call _buildResults = function (){ var _RowList = elemCollection.selectNodes("/data[@col = 'urGod']/title"); var tmpResult = ['']; var substringResult=""; for (i=0; i<_RowList.length; i++) { tmpResult.push(_RowList[i].text,iDom3.Global.Delimiter); } ... //this variant works elemCollection = iDom3.Table.all["spis"].XML.DOM _buildResults = function (){ var _RowList = elemCollection.selectNodes("/suite/table/rows/row/data[@col = 'urGod']/title"); var tmpResult = ['']; var substringResult=""; for (i=0; i<_RowList.length; i++) { tmpResult.push(_RowList[i].text,iDom3.Global.Delimiter); } ... The problem is, I can't find a way to use the subresults to get what I need.

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  • Why use NoSQL over Materialized Views?

    - by JustinT
    There has been a lot of talk recently about NoSQL. The #1 reason why I hear people use NoSQL is because they start to de-normalize their DBMS data so much so, to increase performance, that they end up with just one table with all of their data within that single table. With Materialized Views however, you can keep your data normalized, yet have it stored as a single table view for the same reasons why you'd use NoSQL. As such, why would someone use NoSQL over Materialized Views?

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  • how to limit the number of datas in pdf

    - by udaya
    Hi I am exporting data from php page to word,, there i get 'n' number of datas in each page .... How to set the maximum number of data that a word page can contain ,,,, I want only 20 datas in a single page This is the coding i use to export the data to pdf In mysql_table.php the table for the pdf document is be generated <?php require('mysql_table.php'); class PDF extends PDF_MySQL_Table { function Header() { //Title $this->SetFont('Arial','',18); $this->Cell(0,6,'Country details',0,1,'C'); $this->Ln(10); parent::Header(); } } //Connect to database mysql_connect('localhost','root',''); mysql_select_db('cms'); $pdf=new PDF(); $pdf->AddPage(); //First table: put all columns automatically $pdf->Table("SELECT (SELECT COUNT(*) FROM tblentercountry t2 WHERE t2.dbName <= t1.dbName and dbIsDelete='0') AS SLNO ,dbName as Namee,t3.dbCountry as Country,t4.dbState as State,t5.dbTown as Town FROM tblentercountry t1 join tablecountry as t3, tablestate as t4, tabletown as t5 where t1.dbIsDelete='0' and t1.dbCountryId=t3.dbCountryId and t1.dbStateId=t4.dbStateId and t1.dbTownId=t5.dbTownId order by dbName"); $pdf->AddPage(); //Second table: specify 3 columns $pdf->AddCol('rank',20,'','C'); $pdf->AddCol('name',20,'tablecountry'); $pdf->AddCol('pop',20,'Pop (2001)','R'); $prop=array('HeaderColor'=>array(255,150,100), 'color1'=>array(210,245,255), 'color2'=>array(255,255,210), 'padding'=>2); //$pdf->Table('select dbCountry,dbCountryId from tablecountry limit 0,10',$prop); $pdf->Output(); ?> How to limit the number of datas in a page

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  • Mysql query help - Alter this mysql query to get these results?

    - by sandeepan-nath
    Please execute the following queries first to set up so that you can help me:- CREATE TABLE IF NOT EXISTS `Tutor_Details` ( `id_tutor` int(10) NOT NULL auto_increment, `firstname` varchar(100) NOT NULL default '', `surname` varchar(155) NOT NULL default '', PRIMARY KEY (`id_tutor`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=41 ; INSERT INTO `Tutor_Details` (`id_tutor`,`firstname`, `surname`) VALUES (1, 'Sandeepan', 'Nath'), (2, 'Bob', 'Cratchit'); CREATE TABLE IF NOT EXISTS `Classes` ( `id_class` int(10) unsigned NOT NULL auto_increment, `id_tutor` int(10) unsigned NOT NULL default '0', `class_name` varchar(255) default NULL, PRIMARY KEY (`id_class`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=229 ; INSERT INTO `Classes` (`id_class`,`class_name`, `id_tutor`) VALUES (1, 'My Class', 1), (2, 'Sandeepan Class', 2); CREATE TABLE IF NOT EXISTS `Tags` ( `id_tag` int(10) unsigned NOT NULL auto_increment, `tag` varchar(255) default NULL, PRIMARY KEY (`id_tag`), UNIQUE KEY `tag` (`tag`), KEY `id_tag` (`id_tag`), KEY `tag_2` (`tag`), KEY `tag_3` (`tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=18 ; INSERT INTO `Tags` (`id_tag`, `tag`) VALUES (1, 'Bob'), (6, 'Class'), (2, 'Cratchit'), (4, 'Nath'), (3, 'Sandeepan'), (5, 'My'); CREATE TABLE IF NOT EXISTS `Tutors_Tag_Relations` ( `id_tag` int(10) unsigned NOT NULL default '0', `id_tutor` int(10) default NULL, KEY `Tutors_Tag_Relations` (`id_tag`), KEY `id_tutor` (`id_tutor`), KEY `id_tag` (`id_tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `Tutors_Tag_Relations` (`id_tag`, `id_tutor`) VALUES (3, 1), (4, 1), (1, 2), (2, 2); CREATE TABLE IF NOT EXISTS `Class_Tag_Relations` ( `id_tag` int(10) unsigned NOT NULL default '0', `id_class` int(10) default NULL, `id_tutor` int(10) NOT NULL, KEY `Class_Tag_Relations` (`id_tag`), KEY `id_class` (`id_class`), KEY `id_tag` (`id_tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `Class_Tag_Relations` (`id_tag`, `id_class`, `id_tutor`) VALUES (5, 1, 1), (6, 1, 1), (3, 2, 2), (6, 2, 2); In the present system data which I have given , tutor named "Sandeepan Nath" has has created class named "My Class" and tutor named "Bob Cratchit" has created class named "Sandeepan Class". Requirement - To execute a single query with limit on the results to show search results as per AND logic on the search keywords like this:- If "Sandeepan Class" is searched , Tutor Sandeepan Nath's record from Tutor Details table is returned(because "Sandeepan" is the firstname of Sandeepan Nath and Class is present in class name of Sandeepan's class) If "Class" is searched Both the tutors from the Tutor_details table are fetched because Class is present in the name of the class created by both the tutors. Following is what I have so far achieved (PHP Mysql):- <?php $searchTerm1 = "Sandeepan"; $searchTerm2 = "Class"; mysql_select_db("test"); $sql = "SELECT td.* FROM Tutor_Details AS td LEFT JOIN Tutors_Tag_Relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor LEFT JOIN Classes AS wc ON td.id_tutor = wc.id_tutor LEFT JOIN Class_Tag_Relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN Tags as t1 on ((t1.id_tag = ttagrels.id_tag) OR (t1.id_tag = wtagrels.id_tag)) LEFT JOIN Tags as t2 on ((t2.id_tag = ttagrels.id_tag) OR (t2.id_tag = wtagrels.id_tag)) where t1.tag LIKE '%".$searchTerm1."%' AND t2.tag LIKE '%".$searchTerm2."%' GROUP BY td.id_tutor LIMIT 10 "; $result = mysql_query($sql); echo $sql; if($result) { while($rec = mysql_fetch_object($result)) $recs[] = $rec; //$rec = mysql_fetch_object($result); echo "<br><br>"; if(is_array($recs)) { foreach($recs as $each) { print_r($each); echo "<br>"; } } } ?> But the results are :- If "Sandeepan Nath" is searched, it does not return any tutor (instead of only Sandeepan's row) If "Sandeepan Class" is searched, it returns Sandeepan's row (instead of Both tutors ) If "Bob Class" is searched, it correctly returns Bob's row If "Bob Cratchit" is searched, it does not return any tutor (instead of only

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  • Which non-clustered index should I use?

    - by Junior Mayhé
    Here I am studying nonclustered indexes on SQL Server Management Studio. I've created a table with more than 1 million records. This table has a primary key. CREATE TABLE [dbo].[Customers]( [CustomerId] [int] IDENTITY(1,1) NOT NULL, [CustomerName] [varchar](100) NOT NULL, [Deleted] [bit] NOT NULL, [Active] [bit] NOT NULL, CONSTRAINT [PK_Customers] PRIMARY KEY CLUSTERED ( [CustomerId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] This is the query I'll be using to see what execution plan is showing: SELECT CustomerName FROM Customers Well, executing this command with no additional non-clustered index, it leads the execution plan to show me: I/O cost = 3.45646 Operator cost = 4.57715 Now I'm trying to see if it's possible to improve performance, so I've created a non-clustered index for this table: 1) First non-clustered index CREATE NONCLUSTERED INDEX [IX_CustomerID_CustomerName] ON [dbo].[Customers] ( [CustomerId] ASC, [CustomerName] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO Executing again the select against Customers table, the execution plan shows me: I/O cost = 2.79942 Operator cost = 3.92001 It seems better. Now I've deleted this just created non-clustered index, in order to create a new one: 2) First non-clustered index CREATE NONCLUSTERED INDEX [IX_CustomerIDIncludeCustomerName] ON [dbo].[Customers] ( [CustomerId] ASC ) INCLUDE ( [CustomerName]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this new non-clustered index, I've executed the select statement again and the execution plan shows me the same result: I/O cost = 2.79942 Operator cost = 3.92001 So, which non-clustered index should I use? Why the costs are the same on execution plan for I/O and Operator? Am I doing something wrong or this is expected? thank you

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  • Query doesn't use a covering-index when applicable

    - by Dor
    I've downloaded the employees database and executed some queries for benchmarking purposes. Then I noticed that one query didn't use a covering index, although there was a corresponding index that I created earlier. Only when I added a FORCE INDEX clause to the query, it used a covering index. I've uploaded two files, one is the executed SQL queries and the other is the results. Can you tell why the query uses a covering-index only when a FORCE INDEX clause is added? The EXPLAIN shows that in both cases, the index dept_no_from_date_idx is being used anyway. To adapt myself to the standards of SO, I'm also writing the content of the two files here: The SQL queries: USE employees; /* Creating an index for an index-covered query */ CREATE INDEX dept_no_from_date_idx ON dept_emp (dept_no, from_date); /* Show `dept_emp` table structure, indexes and generic data */ SHOW TABLE STATUS LIKE "dept_emp"; DESCRIBE dept_emp; SHOW KEYS IN dept_emp; /* The EXPLAIN shows that the subquery doesn't use a covering-index */ EXPLAIN SELECT SQL_NO_CACHE * FROM dept_emp INNER JOIN ( /* The subquery should use a covering index, but isn't */ SELECT SQL_NO_CACHE emp_no, dept_no FROM dept_emp WHERE dept_no="d001" ORDER BY from_date DESC LIMIT 20000,50 ) AS `der` USING (`emp_no`, `dept_no`); /* The EXPLAIN shows that the subquery DOES use a covering-index, thanks to the FORCE INDEX clause */ EXPLAIN SELECT SQL_NO_CACHE * FROM dept_emp INNER JOIN ( /* The subquery use a covering index */ SELECT SQL_NO_CACHE emp_no, dept_no FROM dept_emp FORCE INDEX(dept_no_from_date_idx) WHERE dept_no="d001" ORDER BY from_date DESC LIMIT 20000,50 ) AS `der` USING (`emp_no`, `dept_no`); The results: -------------- /* Creating an index for an index-covered query */ CREATE INDEX dept_no_from_date_idx ON dept_emp (dept_no, from_date) -------------- Query OK, 331603 rows affected (33.95 sec) Records: 331603 Duplicates: 0 Warnings: 0 -------------- /* Show `dept_emp` table structure, indexes and generic data */ SHOW TABLE STATUS LIKE "dept_emp" -------------- +----------+--------+---------+------------+--------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------+ | Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment | +----------+--------+---------+------------+--------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------+ | dept_emp | InnoDB | 10 | Compact | 331883 | 36 | 12075008 | 0 | 21544960 | 29360128 | NULL | 2010-05-04 13:07:49 | NULL | NULL | utf8_general_ci | NULL | | | +----------+--------+---------+------------+--------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------+ 1 row in set (0.47 sec) -------------- DESCRIBE dept_emp -------------- +-----------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+-------+ | emp_no | int(11) | NO | PRI | NULL | | | dept_no | char(4) | NO | PRI | NULL | | | from_date | date | NO | | NULL | | | to_date | date | NO | | NULL | | +-----------+---------+------+-----+---------+-------+ 4 rows in set (0.05 sec) -------------- SHOW KEYS IN dept_emp -------------- +----------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +----------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ | dept_emp | 0 | PRIMARY | 1 | emp_no | A | 331883 | NULL | NULL | | BTREE | | | dept_emp | 0 | PRIMARY | 2 | dept_no | A | 331883 | NULL | NULL | | BTREE | | | dept_emp | 1 | emp_no | 1 | emp_no | A | 331883 | NULL | NULL | | BTREE | | | dept_emp | 1 | dept_no | 1 | dept_no | A | 7 | NULL | NULL | | BTREE | | | dept_emp | 1 | dept_no_from_date_idx | 1 | dept_no | A | 13 | NULL | NULL | | BTREE | | | dept_emp | 1 | dept_no_from_date_idx | 2 | from_date | A | 165941 | NULL | NULL | | BTREE | | +----------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ 6 rows in set (0.23 sec) -------------- /* The EXPLAIN shows that the subquery doesn't use a covering-index */ EXPLAIN SELECT SQL_NO_CACHE * FROM dept_emp INNER JOIN ( /* The subquery should use a covering index, but isn't */ SELECT SQL_NO_CACHE emp_no, dept_no FROM dept_emp WHERE dept_no="d001" ORDER BY from_date DESC LIMIT 20000,50 ) AS `der` USING (`emp_no`, `dept_no`) -------------- +----+-------------+------------+--------+----------------------------------------------+-----------------------+---------+------------------------+-------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+----------------------------------------------+-----------------------+---------+------------------------+-------+-------------+ | 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 50 | | | 1 | PRIMARY | dept_emp | eq_ref | PRIMARY,emp_no,dept_no,dept_no_from_date_idx | PRIMARY | 16 | der.emp_no,der.dept_no | 1 | | | 2 | DERIVED | dept_emp | ref | dept_no,dept_no_from_date_idx | dept_no_from_date_idx | 12 | | 21402 | Using where | +----+-------------+------------+--------+----------------------------------------------+-----------------------+---------+------------------------+-------+-------------+ 3 rows in set (0.09 sec) -------------- /* The EXPLAIN shows that the subquery DOES use a covering-index, thanks to the FORCE INDEX clause */ EXPLAIN SELECT SQL_NO_CACHE * FROM dept_emp INNER JOIN ( /* The subquery use a covering index */ SELECT SQL_NO_CACHE emp_no, dept_no FROM dept_emp FORCE INDEX(dept_no_from_date_idx) WHERE dept_no="d001" ORDER BY from_date DESC LIMIT 20000,50 ) AS `der` USING (`emp_no`, `dept_no`) -------------- +----+-------------+------------+--------+----------------------------------------------+-----------------------+---------+------------------------+-------+--------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+----------------------------------------------+-----------------------+---------+------------------------+-------+--------------------------+ | 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 50 | | | 1 | PRIMARY | dept_emp | eq_ref | PRIMARY,emp_no,dept_no,dept_no_from_date_idx | PRIMARY | 16 | der.emp_no,der.dept_no | 1 | | | 2 | DERIVED | dept_emp | ref | dept_no_from_date_idx | dept_no_from_date_idx | 12 | | 37468 | Using where; Using index | +----+-------------+------------+--------+----------------------------------------------+-----------------------+---------+------------------------+-------+--------------------------+ 3 rows in set (0.05 sec) Bye

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  • Datamodel for a MVC learning project

    - by Dofs
    Hi, I am trying to learn Microsoft MVC 2, and have in that case found a small project I wanted to deploy it on. My idea was to simulate a restaurant where you can order a table. Basics: A user can only reserve a full table, so I don't have the trouble of merging people on different tables. A person can order a table for a certain amount of hours. My question was how I could make the data model the smartest way. I thought of just having a my database like this: Table { Id, TableName } Reservations { Id TableId ReservedFrom ReservedTo UserId } User { UserId UserName ... } By doing it this way I would have to program a lot of the logic in e.g. the business layer, to support which tables are occupied at what time, instead of having the data model handle it. Therefore do you guys have a better way to do this?

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  • Searching 2 fields at the same time

    - by donpal
    I have a table of first and last names firstname lastname --------- --------- Joe Robertson Sally Robert Jim Green Sandra Jordan I'm trying to search this table based on an input that consists of the full name. For example: input: Joe Robert I thought about using SELECT * FROM tablename WHERE firstname LIKE BUT the table stores the first and last name separately, so I'm not sure how to do the search in this case

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  • Is my understanding of "select distinct" correct?

    - by paxdiablo
    We recently discovered a performance problem with one of our systems and I think I have the fix but I'm not certain my understanding is correct. In simplest form, we have a table blah into which we accumulate various values based on a key field. The basic form is: recdate date rectime time system varchar(20) count integer accum1 integer accum2 integer There are a lot more accumulators than that but they're all of the same form. The primary key is made up of recdate, rectime and system. As values are collected to the table, the count for a given recdate/rectime/system is incremented and the values for that key are added to the accumulators. That means the averages can be obtained by using accumN / count. Now we also have a view over that table specified as follows: create view blah_v ( recdate, rectime, system, count, accum1, accum2 ) as select distinct recdate, rectime, system, count, value (case when count > 0 then accum1 / count end, 0), value (case when count > 0 then accum2 / count end, 0) from blah; In other words, the view gives us the average value of the accumulators rather than the sums. It also makes sure we don't get a divide-by-zero in those cases where the count is zero (these records do exist and we are not allowed to remove them so don't bother telling me they're rubbish - you're preaching to the choir). We've noticed that the time difference between doing: select distinct recdate from XX varies greatly depending on whether we use the table or the view. I'm talking about the difference being 1 second for the table and 27 seconds for the view (with 100K rows). We actually tracked it back to the select distinct. What seems to be happening is that the DBMS is actually loading all the rows in and sorting them so as to remove duplicates. That's fair enough, it's what we stupidly told it to do. But I'm pretty sure the fact that the view includes every component of the primary key means that it's impossible to have duplicates anyway. We've validated the problem since, if we create another view without the distinct, it performs at the same speed as the underlying table. I just wanted to confirm my understanding that a select distinct can not have duplicates if it includes all the primary key components. If that's so, then we can simply change the view appropriately.

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