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  • Multiple values in a column

    - by Adnan
    Hi I need some advice regarding multiple records. I have a table with fields username,*message* and message_to. the scenario could be of sending same message to multiple users in a go. What do you suggest? will it be efficient to save all recipients in a single column with comma separated values or I add multiple entries ? Thanks /A

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  • how to get transform a local image to a web accessable image

    - by hguser
    Hi: Generally,if we want to display a image in the web page,we give the uri of the image resource like: http://host:port/image/xxx.jpg. Now,there are some images in my file system,and I save its absolute path in the db. Like this; id name address image 1 xxxx xxxx C:/images/xxx.jpg Now if the entity is retrived,its image should be displayed in the page. How to make it? What I thought is copy the image under the web server dir,then build its url,then the page can render it. But I wonder if this is a good idea? Is there any other way?

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  • How do I link ASP.NET membership/role users to tables in db?

    - by SnapConfig.com
    I am going to use forms authentication but I want to be able to link the asp.net users to some tables in the db for example If I have a class and students (as roles) I'll have a class students table. I'm planning to put in a Users table containing a simple int userid and ASP.NET username in there and put userid wherever I want to link the users. Does that sound good? any other options of modeling this? it does sound a bit convoluted?

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  • Hibernate Auto-Increment not working

    - by dharga
    I have a column in my DB that is set with Identity(1,1) and I can't get hibernate annotations to work for it. I get errors when I try to create a new record. In my entity I have the following. @GeneratedValue(strategy=GenerationType.IDENTITY, generator="native") @Column(name="SeqNo", unique=true, nullable=false) BigDecimal seqNo; But when I try to add a new record I get the following error. Cannot insert explicit value for identity column in table 'MemberSelectedOptions' when IDENTITY_INSERT is set to OFF. I don't want to set IDENTIY_INSERT to ON because I want the identity column in the db to manage the values. The SQL that is run is the following; where you can clearly see the insert. insert into dbo.MemberSelectedOptions (OptionStatusCd, EffectiveDate, TermDate, SelectionStatusDate, SysLstUpdtUserId, SysLstTrxDtm, SourceApplication, GroupId, MemberId, OptionId, SeqNo) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) What am I missing?

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  • How would you structure your entity model for storing arbitrary key/value data with different data t

    - by Nathan Ridley
    I keep coming across scenarios where it will be useful to store a set of arbitrary data in a table using a per-row key/value model, rather than a rigid column/field model. The problem is, I want to store the values with their correct data type rather than converting everything to a string. This means I have to choose either a single table with multiple nullable columns, one for each data type, or a set of value tables, one for each data type. I'm also unsure as to whether I should use full third normal form and separate the keys into a separate table, referencing them via a foreign key from the value table(s), or if it would be better to keep things simple and store the string keys in the value table(s) and accept the duplication of strings. Old/bad: This solution makes adding additional values a pain in a fluid environment because the table needs to be modified regularly. MyTable ============================ ID Key1 Key2 Key3 int int string date ---------------------------- 1 Value1 Value2 Value3 2 Value4 Value5 Value6 Single Table Solution This solution allows simplicity via a single table. The querying code still needs to check for nulls to determine which data type the field is storing. A check constraint is probably also required to ensure only one of the value fields contains non-nulll data. DataValues ============================================================= ID RecordID Key IntValue StringValue DateValue int int string int string date ------------------------------------------------------------- 1 1 Key1 Value1 NULL NULL 2 1 Key2 NULL Value2 NULL 3 1 Key3 NULL NULL Value3 4 2 Key1 Value4 NULL NULL 5 2 Key2 NULL Value5 NULL 6 2 Key3 NULL NULL Value6 Multiple-Table Solution This solution allows for more concise purposing of each table, though the code needs to know the data type in advance as it needs to query a different table for each data type. Indexing is probably simpler and more efficient because there are less columns that need indexing. IntegerValues =============================== ID RecordID Key Value int int string int ------------------------------- 1 1 Key1 Value1 2 2 Key1 Value4 StringValues =============================== ID RecordID Key Value int int string string ------------------------------- 1 1 Key2 Value2 2 2 Key2 Value5 DateValues =============================== ID RecordID Key Value int int string date ------------------------------- 1 1 Key3 Value3 2 2 Key3 Value6 How do you approach this problem? Which solution is better? Also, should the key column be separated into a separate table and referenced via a foreign key or be should it be kept in the value table and bulk updated if for some reason the key name changes?

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  • Django: How/Where to store a value for a session without unnecessary DB hits

    - by GerardJP
    Hi all, I have an extended userprofile with AUTH_PROFILE_MODULE (ref: http://tinyurl.com/yhracqq) I would like to set a user.is_guru() method similar to user.is_active(). This would results for al views (or rather templates) to e.g. disable/enable certain user messages, displaying of widgets, etc. The boolean is stored in the extended user profile model, but I want to avoid hitting the DB for every view. So the questions is .. Do I use a context_processor, a template tag, session_dict or what have you to, possible cached, store this info for the duration of the users visit. Note: I dont have performance issues, so it's definitely filed under premature optimization. I just want to avoid generating extra work in the future :). Any pointers are very welcome. Thanx and greetz! Gerard.

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  • Will MySql caching cause performance problems?

    - by Camran
    I am about to upload my website onto a VPS. It is a classifieds website, where all data is stored in MySql and Solr. I wonder if when using MySql:s cache, the server will slow down? Ie, if somebody makes a search for the first time, and MySql is to cache the query, will the caching make the server slower than if it would not cache anything? After the caching is done I know things will improve in terms of performance... But I would like to know if I should even use the cache or not, what do you think? Thanks

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  • How to query range of data in DB2 with highest performance?

    - by Fuangwith S.
    Usually, I need to retrieve data from a table in some range; for example, a separate page for each search result. In MySQL I use LIMIT keyword but in DB2 I don't know. Now I use this query for retrieve range of data. SELECT * FROM( SELECT SMALLINT(RANK() OVER(ORDER BY NAME DESC)) AS RUNNING_NO , DATA_KEY_VALUE , SHOW_PRIORITY FROM EMPLOYEE WHERE NAME LIKE 'DEL%' ORDER BY NAME DESC FETCH FIRST 20 ROWS ONLY ) AS TMP ORDER BY TMP.RUNNING_NO ASC FETCH FIRST 10 ROWS ONLY but I know it's bad style. So, how to query for highest performance?

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  • what's wrong with this code?

    - by user329820
    Hi this is my code which will not work correctly ! what is wrong with its data type :( thanks CREATE TABLE T1 (A INTEGER NOT NULL); CREATE TABLE T3 (A SMALLINT NOT NULL); INSERT T1 VALUES (32768.5); SELECT * FROM T1; INSERT T3 SELECT * FROM T1; SELECT * FROM T3;

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  • Help me write a nicer SQL query in Rails

    - by Sainath Mallidi
    Hi, I am trying to write an SQL query to update some of the attributes that are regularly pulled from source. the output will be a text file with the following fields: author, title, date, popularity I have two tables to update one is the author information and the other is popularity table. And the Author Active Record object has one popularity. Currently I'm doing it like this.\ arr.each { |x| x = x.split(" ") results = Author.find_by_sql("SELECT authors.id FROM authors, priorities WHERE authors.id=popularity.authors_id AND authors.author = x[0]") results[0].popularity.update_attribute("popularity", x[3]) I need two tables because the popularity keeps changing, and I need only the top 1000 popular ones, but I still need to keep the previously popular ones also. Is there any nicer way to do this, instead of one query for every new object. Thanks.

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  • Mysql- "FLUSH TABLES WITH READ LOCK" started automatically

    - by ming yeow
    I would like to understand how this happened. I was running a query that would take a long time, but should not lock up any table. However, my dbs were practically down - it seems like it was being locked up by "FLUSH TABLES WITH READ LOCK" 03:21:31 select type_id, count(*) from guid_target_infos group by type_id 02:38:11 select type_id, count(*) from guid_infos group by type_id 02:24:29 FLUSH TABLES WITH READ LOCK But i did not start this command. can someone tell me why it was started automatically?

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  • I have data about deadlocks, but I can't understand why they occur

    - by Alex
    I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL Profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second Linq-to-SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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  • Any tools or techniques for validating constraints programmatically between databases?

    - by Brandon
    If you had two databases, that had two tables between them that would normally implement a one to one (or many to many) constraint but cannot since they are separate databases, how would you validate this relationship in an application or test? Is there a simple way to do this? For example, a tool or technique that can, given a constraint type, tables and fields, does the validation. I imagine that this isn't the first time this come up so I'm hoping people can share their solution. Thanks.

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  • Why does this simple MySQL procedure take way too long to complete?

    - by Howard Guo
    This is a very simple MySQL stored procedure. Cursor "commission" has only 3000 records, but the procedure call takes more than 30 seconds to run. Why is that? DELIMITER // DROP PROCEDURE IF EXISTS apply_credit// CREATE PROCEDURE apply_credit() BEGIN DECLARE done tinyint DEFAULT 0; DECLARE _pk_id INT; DECLARE _eid, _source VARCHAR(255); DECLARE _lh_revenue, _acc_revenue, _project_carrier_expense, _carrier_lh, _carrier_acc, _gross_margin, _fsc_revenue, _revenue, _load_count DECIMAL; DECLARE commission CURSOR FOR SELECT pk_id, eid, source, lh_revenue, acc_revenue, project_carrier_expense, carrier_lh, carrier_acc, gross_margin, fsc_revenue, revenue, load_count FROM ct_sales_commission; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; DELETE FROM debug; OPEN commission; REPEAT FETCH commission INTO _pk_id, _eid, _source, _lh_revenue, _acc_revenue, _project_carrier_expense, _carrier_lh, _carrier_acc, _gross_margin, _fsc_revenue, _revenue, _load_count; INSERT INTO debug VALUES(concat('row ', _pk_id)); UNTIL done = 1 END REPEAT; CLOSE commission; END// DELIMITER ; CALL apply_credit(); SELECT * FROM debug;

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  • In mySQL, Is it possible to SELECT from two tables and merge the columns?

    - by Travis
    If I have two tables in mysql that have similar columns... TABLEA id name somefield1 TABLEB id name somefield1 somefield2 How do I structure a SELECT statement so that I can SELECT from both tables simultaneously, and have the result sets merged for the columns that are the same? So for example, I am hoping to do something like... SELECT name, somefield1 FROM TABLEA, TABLEB WHERE name="mooseburgers"; ...and have the name, and somefield1 columns from both tables merged together in the result set. Thank-you for your help!

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  • What's the best way to test SQL Server connection programmatically?

    - by backslash17
    I need to develop a single routine that will be fired each 5 minutes to check if a list of SQL Servers (10 to 12) are up and running. I can try to obtain a simple query in each one of the servers but this means that I have to create a table, view or stored procedure in every server, even if I use any already made SP I need to have a registered user in each server too. The servers are not in the same physical location so having those requirements would be a complex task. Is there a way to simply "ping" from C# one SQL Server? Thanks in advance!

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  • how to write this query using joins?

    - by aquero
    Hi, i have a table campaign which has details of campaign mails sent. campaign_table: campaign_id campaign_name flag 1 test1 1 2 test2 1 3 test3 0 another table campaign activity which has details of campaign activities. campaign_activity: campaign_id is_clicked is_opened 1 0 1 1 1 0 2 0 1 2 1 0 I want to get all campaigns with flag value 3 and the number of is_clicked columns with value 1 and number of columns with is_opened value 1 in a single query. ie. campaign_id campaign_name numberofclicks numberofopens 1 test1 1 1 2 test2 1 1 I did this using sub-query with the query: select c.campaign_id,c.campaign_name, (SELECT count(campaign_id) from campaign_activity WHERE campaign_id=c.id AND is_clicked=1) as numberofclicks, (SELECT count(campaign_id) from campaign_activity WHERE campaign_id=c.id AND is_clicked=1) as numberofopens FROM campaign c WHERE c.flag=1 But people say that using sub-queries are not a good coding convention and you have to use join instead of sub-queries. But i don't know how to get the same result using join. I consulted with some of my colleagues and they are saying that its not possible to use join in this situation. Is it possible to get the same result using joins? if yes, please tell me how.

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  • How to undo SQL changes using installer

    - by Sunil Agarwal
    I have installer to install procedures, scripts, views, etc in SQL server 2005/2008. Now I want to add a condition in the installer like if there is any error while installing, I want to undo all the changes done in SQL server. I tried to store the procedures, views, etc which I am changing while installing and reverting them back if I get any error. But am not able to do it the way I want. Can someone guide me if he had done the same thing? To specify I am using WIX installer. Also if someone has tried SMO, it will be of great help.

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  • Select where and where not

    - by Simon
    I have a table containing lessons that I called "cours" (french) and I have several cours inside and I have linked them to students with a table between them to see if they go to the lessons or not. I would like to return data with the SELECT and the data that are NOT select. So, If one student follow 3 courses of 5, I would like to return the 3 courses that he follow and the 2 courses that he doesn't follow. Is there a way to do it ?

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  • Synchronizing MySQL databases

    - by Wasim
    Hi all, I have a maintanance problem synchronizing my MySQL data bases . These are the databases I have : My development DB : Here I make my curret development changes . Staging DB : I need to make all the changes I did in the development on it before using , currently I hold migration scripts for structure and data. Production DB : A production environment . Have to do exacly the same as the staging . My problem , is sync. the structure , and some of the data. This is really a very hard work to maintaine. Is there any technics , tools to do with MySQL . What is replication , is it good for my situation , how to use it . Thanks in advance ...

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