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  • Update all table rows but top N in Mysql

    - by arthurprs
    I was trying to run the following query UPDATE blog_post SET `thumbnail_present`=0, `thumbnail_size`=0, `thumbnail_data`='' WHERE `blog_post` NOT IN ( SELECT `blog_post` FROM blog_post ORDER BY `blog_post` DESC LIMIT 10) But Mysql doesn't allow 'LIMIT' in an 'IN' subquery. I think I can make a select to count the table rows and then make an ordered update limited by 'COUNT - 10', but I was wondering if there is a better way. Thanks in advance.

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  • Get smallest date for each element in access query

    - by skerit
    So I have a table containing different elements and dates. It basically looks like this: actieElement beginDatum 1 1/01/2010 1 1/01/2010 1 10/01/2010 2 1/02/2010 2 3/02/2010 What I now need is the smallest date for every actieElement. I've found a solution using a simple GROUP BY statement, but that way the query loses its scope and you can't change anything anymore. Without the GROUP BY statement I get multiple dates for every actieElement because certain dates are the same. I thought of something like this, but it also does not work as it would give the subquery more then 1 record: SELECT s1.actieElement, s1.begindatum FROM tblActieElementLink AS s1 WHERE (((s1.actieElement)=(SELECT TOP 1 (s2.actieElement) FROM tblActieElementLink s2 WHERE s1.actieElement = s2.actieElement ORDER BY s2.begindatum ASC)));

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  • How efficient is a details table?

    - by Jeffrey Lott
    At my job, we have pseudo-standard of creating one table to hold the "standard" information for an entity, and a second table, named like 'TableNameDetails', which holds optional data elements. On average, for every row in the main table will have about 8-10 detail rows in it. My question is: What kind of performance impacts does this have over adding these details as additional nullable columns on the main table?

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  • Relating text fields to check boxes in Java

    - by Finzz
    This program requires the user to login and request a database to access. The program then gets a connection object, searches through the database storing the column names into a vector for later use. The problem comes with implementing text fields to allow the user to search for specific values within the database. I can get the check boxes and text fields to appear using a gridlayout and add them to a panel. How do I relate the text fields to their appropriate check box? I've tried adding them to a vector, but then they can't also be added to the panel as well. I've searched for a way to name the text fields as the loop cycles through the column names, but it seems impossible to do without having them declared ahead of time. This can't be done either, as it's impossible to determine the attributes that the user will request. I just need to be able to know the names of the text fields so I can test to see if the user entered information and perform the necessary logic. Let me know if you have to see the rest of the code to give an answer, but hopefully you get the general idea of what I'm trying to accomplish. Picture of UI: try { ResultSet r2 = con.getMetaData().getColumns("", "", rb.getText(), ""); colNames1 = new Vector<String>(); columns1 = new Vector<JCheckBox>(); while (r2.next()) { colNames1.add(r2.getString(4)); JCheckBox cb = new JCheckBox(r2.getString(4)); JTextField tf = new JTextField(10); columns1.add(cb); p3.add(cb); p3.add(tf); } }

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  • IN 'mytextfile.txt' syntax - access

    - by I__
    i would like to use this syntax to update a table in access based on data from a txtfile. fenton in his comments on this answer: http://stackoverflow.com/questions/2992168/read-text-file-line-by-line-and-insert-update-values-in-table/2992337#2992337 said that this is possible and i would like to see the exact syntax please

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  • Oracle global_names DELETE problem

    - by jyzuz
    I'm using a database link to execute a DELETE statement on another DB, but the DB link name doesn't conform to global naming, and this requirement cannot change. Also I have global_names set to false, and cannot be changed either. When I try to use these links however, I receive: ORA-02069: - global_names parameter must be set to TRUE for this operation Cause: A remote mapping of the statement is required but cannot be achieved because GLOBAL_NAMES should be set to TRUE for it to be achieved. - Action: Issue `ALTER SESSION SET GLOBAL_NAMES = TRUE` (if possible) What is the alternative action when setting global_names=true is not possible? Cheers, Jean

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  • How to automatically check out a database file in a source controlled web application ?

    - by TheRHCP
    Hello, I am working on an ASP.NET web application, we are a small team (4 students) and we do not have access to a dedicated server to host the database instance. So for this web application we decided just to put the database file in the App_Data folder. The problem is that our project is source controled on TFS, so every time you open the solution and try to launch the web application, we get an expcetion saying that database is read-only. That is logical because the databse file is not automatically checked-out. Is there a workaround to avoid a manual check-out of the database file everytime we open the solution ? Thanks.

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  • MySQL Query to find consecutive available times of variable lenth

    - by Armaconn
    I have an events table that has user_id, date ('2013-10-01'), time ('04:15:00'), and status_id; What I am looking to find is a solution similar to http://stackoverflow.com/questions/2665574/find-consecutive-rows-calculate-duration but I need I need two additional components: 1) Take date into consideration, so 10/1/2013 at 11:00 PM - 10/2/2013 at 3:00AM. Feel free to just put in a fake date range (like '2013-10-01' to '2013-10-31') 2) Limit output to only include when there are 4+ consecutive times (each event is 15 minutes and I want it to display minimum blocks of an hour, but would also like to be able to switch this restriction to 1.5 hours or some other duration if possible). SUMMARY - Looking for a query that provides the start and end times for a set of events that have the same user_id, status_id, and are in a continuous series based on date and time. For which I can restrict results based on date range and minimum series duration. So the output should have: user_id, date_start, time_start, date_end, time_end, status_id, duration CREATE TABLE `events` ( `event_id` int(11) NOT NULL auto_increment COMMENT 'ID', `user_id` int(11) NOT NULL, `date` date NOT NULL, `time` time NOT NULL, `status_id` int(11) default NULL, PRIMARY KEY (`event_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1568 ; INSERT INTO `events` VALUES(1, 101, '2013-08-14', '23:00:00', 2); INSERT INTO `events` VALUES(2, 101, '2013-08-14', '23:15:00', 2); INSERT INTO `events` VALUES(3, 101, '2013-08-14', '23:30:00', 2); INSERT INTO `events` VALUES(4, 101, '2013-08-14', '23:45:00', 2); INSERT INTO `events` VALUES(5, 101, '2013-08-15', '00:00:00', 2); INSERT INTO `events` VALUES(6, 101, '2013-08-15', '00:15:00', 1); INSERT INTO `events` VALUES(7, 500, '2013-08-14', '23:45:00', 1); INSERT INTO `events` VALUES(8, 500, '2013-08-15', '00:00:00', 1); INSERT INTO `events` VALUES(9, 500, '2013-08-15', '00:15:00', 2); INSERT INTO `events` VALUES(10, 500, '2013-08-15', '00:30:00', 2); INSERT INTO `events` VALUES(11, 500, '2013-08-15', '00:45:00', 1); Desired output row |user_id | date_start | time_start | date_end | time_end | status_id | duration 1 |101 |'2013-08-14'| '23:00:00' |'2013-08-15'|'00:15:00'| 2 | 5 2 |101 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:30:00'| 1 | 1 3 |500 |'2013-08-14'| '00:23:45' |'2013-08-15'|'00:15:00'| 1 | 2 4 |500 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:45:00'| 2 | 2 5 |500 |'2013-08-15'| '00:00:45' |'2013-08-15'|'01:00:00'| 2 | 1 *except that rows 2 and 5 wouldn't appear if duration had to be greater than 30 minutes Thanks for any help that you can provide! And please let me know if there is anything I can further clarify!!

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  • Is count(*) really expensive ?

    - by Anil Namde
    I have a page where I have 4 tabs displaying 4 different reports based off different tables. I obtain the row count of each table using a select count(*) from <table> query and display number of rows available in each table on the tabs. As a result, each page postback causes 5 count(*) queries to be executed (4 to get counts and 1 for pagination) and 1 query for getting the report content. Now my question is: are count(*) queries really expensive -- should I keep the row counts (at least those that are displayed on the tab) in the view state of page instead of querying multiple times? How expensive are COUNT(*) queries ?

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  • possible way to attach database to exe

    - by ali
    i created a small application using c# winforms that uses mssql as a database. is there a way to attach the database to the exe file so i won't need to install sqlserver on all the machines that i want to run the program on?

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  • How to go about writing this classic asp in asp.net

    - by Phil
    I am stuck in converting this snipped to asp.net. set RSLinksCat = conn.Execute("select linkscat.id, linkscat.category from linkscat, contentlinks, links where contentlinks.linksid = links.id and contentlinks.contentid = " & contentid & " and links.linkscatid = linkscat.id order by linkscat.category") <%if not RSLinksCat.EOF then%><h1>Links</h1> <br /> <%do while not RSLinksCat.EOF%> <%set RSLinks = conn.Execute("select * from links where linkscatid = " & RSLinksCat("id") & "")%> <strong><%=RSlinkscat("category")%><strong> <ul> <%do while not RSlinks.EOF%> <li> <a href = "http://<%=RSLinks("url")%>" target="_blank"><%=RSlinks("description")%></a> </li> <%RSLinks.MoveNext loop%> </ul> <%RSLinksCat.MoveNext loop%> <br /> <%end if%><%conn.close%> I'm not sure where to start. Can anyone recommend the correct approach i.e sqldatareaders or repeaters or arrays or? VB code samples most welcome. Thanks

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  • Find all those columns which have only null values, in a MySQL table

    - by Robin v. G.
    The situation is as follows: I have a substantial number of tables, with each a substantial number of columns. I need to deal with this old and to-be-deprecated database for a new system, and I'm looking for a way to eliminate all columns that have - apparently - never been in use. I wanna do this by filtering out all columns that have a value on any given row, leaving me with a set of columns where the value is NULL in all rows. Of course I could manually sort every column descending, but that'd take too long as I'm dealing with loads of tables and columns. I estimate it to be 400 tables with up to 50 (!) columns per table. Is there any way I can get this information from the information_schema? EDIT: Here's an example: column_a column_b column_c column_d NULL NULL NULL 1 NULL 1 NULL 1 NULL 1 NULL NULL NULL NULL NULL NULL The output should be 'column_a' and 'column_c', for being the only columns without any filled in values.

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  • Simple SELECT query problem...

    - by Povylas
    Hi, I have this MySql select query witch seams to have a bug but I am quit "green" so I simple can not see, so maybe you could help? Here is the query: SELECT node_id FROM rate WHERE node_id='".$cat_node_id_string."' LIMIT ".$node_count_star.",".$node_count_end." ORDER BY SUM(amount) GROUP BY node_id Thanks for help in advance...

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  • drop-down combo box-like functionality for queries.

    - by Frank Developer
    Is it possible to provide the following type of fuctionality with informix client tools? As the user types the first two characters of a name, the drop-down list is empty. At the third character, the list fills with just the names beginning with those three characters. At the fourth character, MS-Access completes the first matching name (assuming the combo's AutoExpand is on). Once enough characters are typed to identify the customer, the user tabs to the next field. The time taken to load the combo between keystrokes is minimal. This occurs once only for each entry, unless the user backspaces through the first three characters again. If your list still contains too many records, you can reduce them by another order of magnitude by changing the value of constant conSuburbMin from 3 to 4.

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  • How can I bind an Enum to a DbType of bit or int?

    - by uriDium
    Hi I am using Linq2Sql and want to bind an objects field (which is enum) to either a bit or a int type in the database. For example I want have a gender field in my model. I have already edited the DBML and changed the Type to point to my enum. I want to create Radio buttons (which I think I have figured out) for gender and dropdown lists for other areas using the same idea. My enum looks like this public enum Gender { Male, Female } Mapping between DbType 'int' and Type 'Project.Models.Gender' in Column 'Gender' of Type 'Candidate' is not supported. Any ideas on how to do this mapping. Am I missing something on the enums.

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  • how to do multi insert and obtain ids

    - by liysd
    hi, I want to insert some data into a table (id PK autoincrement, val) with use multi insert INSERT INTO tab (val) VALUES (1), (2), (3) Is it possible to obtain a table of last inserted ids? I'm asking becouse I'm not sure if all will in this form: (n, n+1, n+2). I use mysql inodb.

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  • Database design advice needed.

    - by user346271
    Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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  • SSAS OLAP MDX and relationships

    - by Sonic Soul
    I new to OLAP, and still not sure how to create a relationship between 2 or more entities. I am basing my cube on views. For simplicity sake let's call them like this: viewParent (ParentID PK) viewChild (ChildID PK, ParentID FK) these views have more fields, but they're not important for this question. in my data source, i defined a relationship between viewParent and viewChild using ParentID for the link. As for measures, i was forced to create separate measures for Parent and Child. in my MDX query however, the relationship does not seem to be enforced. If i select record count for parent, child, and add some filters for the parent, the child count is not reflecting it.. SELECT { [Measures].[ParentCount],[Measures].[ChildCount] } ON COLUMNS FROM [Cube] WHERE { ( {[Time].[Month].&[2011-06-01T00:00:00]} ,{[SomeDimension].&[Foo]} ) } the selected ParentCount is correct, but ChildCount is not affected by any of the filters (because they are parent filters). However, since i defined a relationship, how can i take advantage of that to filter children by parent filter?

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  • Inexplicably slow query in MySQL

    - by Brandon M.
    Given this result-set: mysql> EXPLAIN SELECT c.cust_name, SUM(l.line_subtotal) FROM customer c -> JOIN slip s ON s.cust_id = c.cust_id -> JOIN line l ON l.slip_id = s.slip_id -> JOIN vendor v ON v.vend_id = l.vend_id WHERE v.vend_name = 'blahblah' -> GROUP BY c.cust_name -> HAVING SUM(l.line_subtotal) > 49999 -> ORDER BY c.cust_name; +----+-------------+-------+--------+---------------------------------+---------------+---------+----------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+---------------------------------+---------------+---------+----------------------+------+----------------------------------------------+ | 1 | SIMPLE | v | ref | PRIMARY,idx_vend_name | idx_vend_name | 12 | const | 1 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | l | ref | idx_vend_id | idx_vend_id | 4 | csv_import.v.vend_id | 446 | | | 1 | SIMPLE | s | eq_ref | PRIMARY,idx_cust_id,idx_slip_id | PRIMARY | 4 | csv_import.l.slip_id | 1 | | | 1 | SIMPLE | c | eq_ref | PRIMARY,cIndex | PRIMARY | 4 | csv_import.s.cust_id | 1 | | +----+-------------+-------+--------+---------------------------------+---------------+---------+----------------------+------+----------------------------------------------+ 4 rows in set (0.04 sec) I'm a bit baffled as to why the query referenced by this EXPLAIN statement is still taking about a minute to execute. Isn't it true that this query only has to search through 449 rows? Anyone have any idea as to what could be slowing it down so much?

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