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  • how to debug a query that has valid syntax, executes, but returns no results?

    - by Ty W
    So I'm writing a fairly involved query with a half dozen joins, a dependent subquery for [greatest-n-per-group] purposes, grouping, etc. It is syntactically valid, but I've clearly made at least one mistake because it returns nothing. In the past I've debugged valid queries that return nothing by removing joins, executing subqueries on their own, removing WHERE conditions, and removing grouping to see what I would get but so far this one has me stumped. Are there better tools or techniques to use for this sort of thing? This particular query is for MySQL if it matters for any platform-specific tools.

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  • Why would using a Temp table be faster than a nested query?

    - by Mongus Pong
    We are trying to optimise some of our queries. One query is doing the following: SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, INTO [#Gadget] FROM task t SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) as Client FROM [#Gadget] order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC DROP TABLE [#Gadget] (I have removed the complex subquery, cos I dont think its relevant other than to explain why this query has been done as a two stage process.) Now I would have thought it would be far more efficient to merge this down into a single query using subqueries as : SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) FROM ( SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, FROM task t ) as sub order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC This would give the optimiser better information to work out what was going on and avoid any temporary tables. It should be faster. But it turns out it is a lot slower. 8 seconds vs under 5 seconds. I cant work out why this would be the case as all my knowledge of databases imply that subqueries would always be faster than using temporary tables. Can anyone explain what could be going on!?!?

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  • Can't create a MySQL query that generates 4 rows for each row in the table it references.

    - by UkraineTrain
    I need to create a MySQL query that generates 4 rows for each row in the table it references. I need some of the information in those rows to repeat and some to be different. In the table each row stands for one day. I need to break the day up in 6 hour increments, hence the four rows for each entry. I need to create one column which for each day will have '12AM', '6AM', '12PM', and '6PM' values and another column will have the corresponding numeric values calculated for those entries. Thanks a lot in advance and I will really appreciate any help on this.

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  • mySQL: Order by field size/length

    - by Sadi
    Here is a table structure (e.g. test): __________________________________________ | Field Name | Data Type | |________________|_________________________| | id | BIGINT (20) | |________________|_________________________| | title | varchar(25) | |________________|_________________________| | description | text | |________________|_________________________| A query like: SELECT * FROM TEST ORDER BY description; But I would like to order by the field size/length of the field description. The field type will be TEXT or BLOB.

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  • How can I tell when a MySQL table was last updated?

    - by RaGE
    In the footer of my page, I would like to add something like "last updated the xx/xx/200x"; with this date being the last time a certain mySQL table has been updated. What is the best way to do that ? Is there a function to retrieve the date ? Should I make an access to the database everytime my footer is displayed ?

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  • array insert in db

    - by gloris
    Hi, How best to put the array (100 or more length) in the database (MySQL)? I do not want multiple access to the database because it is so loaded. So my solution is as follows: string insert = "INSERT INTO programs (name, id) VALUES "; for(int i = 0; i < name.Length; i++) { if (i != 0) { insert = insert + ",("; } else { insert = insert + "("; } insert = insert + "'" + name[i] + "','" + id[i] + "'"; insert = insert + ")"; } //INSERT INTO programs (name, id) VALUES ('Peter','32'),('Rikko','343') .... But maybe is a faster version? Thanks

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  • making a combined sum of two columns

    - by bsandrabr
    I have a table (apples) containing: cid date_am date_pm ---------------------- 1 1 1 2 2 1 3 1 3 1 1 2 I asked a question earlier (badly) about how I would rank the customers in order of the number of ones(1) they had. The solution was (based on one column): SELECT cid, sum( date_pm ) AS No_of_ones FROM apples WHERE date_am =1 GROUP BY cid ORDER BY no_of_ones DESC This works great for one column but how would I do the same for the sum of the two columns. ie. SELECT cid, sum( date_pm ) AS No_of_ones FROM apples WHERE date_am =1 add to SELECT cid, sum( date_am ) AS No_of_ones FROM apples WHERE date_pm =1 GROUP by cid ORDER by no_of_ones(added) hope I've managed to make that clear enough for you to help -thanks

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  • Can I have a CASE statement within a WHILE loop?

    - by John
    This is what I'm doing: while (@counter < 3 and @newBalance >0) begin CASE when @counter = 1 then ( @monFee1 = @monthlyFee, @newBalance = @newBalance-@fee) when @counter = 2 then ( @monFee2 = @monthlyFee, @newBalance = @newBalance-@fee) END @counter = @counter +1 end I get this error: Incorrect syntax near the keyword 'CASE'. No idea why. Please help!

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  • Use database dynamically

    - by Redi
    This execution it is giving me an error! Any hints of what am I missing? declare @dbname varchar(500) set @dbname='master' Exec (' Use ' + @dbname + ' go create PROCEDURE [dbo].[krijo_database] @dbname nvarchar(2000), @Direktoria varchar(4000) AS BEGIN declare @stringu nvarchar(100) set @stringu = ''CREATE DATABASE '' + @dbname exec (@stringu) End ')

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  • Removing certain characters in all rows that match a regex?

    - by user001
    I'd like to change {foo, {bar}, foobar} to {foo, bar, foobar} in all rows that match '{.*{'. I.e. remove all curly braces { and } except the outer most pair. So doing mysql -h $H -u $U -p$P $DB -B -e "SELECT id FROM t WHERE col REGEXP '{.*{'" > bad.txt selects all the rows that will need this substitution. How do I make this substitution very quickly? EDIT: Could I do it by update table set column = REPLACE(column,'{',''); Then restore the out most pair update table set column = REPLACE(column,'^','{'); update table set column = REPLACE(column,'$','}');

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  • How to add user customized data to database?

    - by CSharperWithJava
    I am trying to design a sqlite database that will store notes. Each of these notes will have common fields like title, due date, details, priority, and completed. In addition though, I would like to add data for more specialized notes like price for shopping list items and author/publisher data for books. I also want to have a few general purpose fields that users can fill with whatever text data they want. How can I design my database table in this case? I could just have a field for each piece of data for every note, but that would waste a lot of fields and I'd like to have other options and suggestions.

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  • reset all logged in users after they shutdown their consoled

    - by gin
    i have list of student who have Nintendo DSs, and they should log in my website to solve some sheets (by using DS Opera browser), when they logged in , (status filed at my DB will change from 0 to 1),also the status change to 0 if they log out, what i need is when the student didn't log out and Shut down their DS's , the status should be 0,, i don't have an idea to it, any suggestion would be helpful for me .. FYI ,DS opera browser limitation here

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  • fastest way to copy a table in mysql

    - by Anon
    which one is the fastest way to completely copy a table on mysql ? CREATE TABLE copy LIKE original; INSERT INTO copy SELECT * FROM original; or CREATE TABLE copy SELECT * FROM original; ALTER TABLE copy ADD PRIMARY KEY (id); or theres another way ? PS. can't use command-line tools like mysqldump, must be on-the-fly.

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  • MS access refusing to combine two tables?

    - by Mahmoud
    hey everyone i have an access 2007 database where i have 2 tables one is exp_cash and exp_cheque each are link to exp_cat, where exp_cat contains categories list where exp_cash contains id,cat_id,exp_date,exp_amount,exp_note same thing in exp_cheque where when i came to combine them nothing in result unless i remove the cat_name from my query i used a simple query which is SELECT DISTINCT exp_cat.cat_name, exp_cash.exp_amount, exp_cheque.exp_amount FROM (exp_cat INNER JOIN exp_cash ON exp_cat.ID = exp_cash.exp_cat_id) INNER JOIN exp_cheque ON exp_cat.ID = exp_cheque.exp_cat_id;

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  • Using NULL in MySQL

    - by JPro
    The data in my dabatase comes from an external source and where ever there is no data passed, I keep NULL in those places. Can anyone tell me if there are any implications in using NULL to represent empty value? Should I follow some other convention like 'data_not_available'? or something like that? Can anyone suggest?

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  • PHP Security checklist (injection, sessions etc)

    - by NoviceCoding
    So what kind of things should a person using PHP and MySql be focused on to maximize security. Things I have done: -mysql_real_escape_string all inputs -validate all inputs after escaping em -Placed random alpha numerics before my table names -50character salt + Ripemd passwords Heres where I think I am slacking: -I know know nothing about sessions and securing them. How unsafe/safe is it if all you are doing is: session_start(); $_SESSION['login']= $login; and checking it with: session_start(); if(isset($_SESSION['login'])){ -I heard something about other forms of injection like cross site injection and what not... -And probably many other things I dont know about. Is there a "checklist"/Quicktut on making php secure? I dont even know what I should be worried about.I kinda regret now not building off cakephp since I am not a pro.

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  • Zend Framework Db Select Join table help

    - by tester2001
    I have this query: SELECT g.title, g.asin, g.platform_id, r.rank FROM games g INNER JOIN ranks r ON ( g.id = r.game_id ) ORDER BY r.rank DESC LIMIT 5` Now, this is my JOIN using Zend_Db_Select but it gives me array error $query = $this-select(); $query-from(array('g' = 'games'), array()); $query-join(array('r' = 'ranks'), 'g.id = r.game_id', array('g.title', 'g.asin', 'g.platform_id', 'r.rank')); $query-order('r.rank DESC'); $query-limit($top); $resultRows = $this-fetchAll($query); return $resultRows; Anyone know what I could be doing wrong? I want to get all the columns in 'games' to show and the 'rank' column in the ranks table.

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  • I insert new parent row and child rowstate changes from Added to unchanged

    - by Joel
    rowsUpdated is an int32 to count how many rows are updated rowsToUpdate = dataset.ParentTable.Select("", "", dataviewRowState.Added) if rowsToUpdate isNot Nothing then for each row as datarow in RowsToUpdate changes the rowstate: rowsUpdated = rowsUpdated + ParentTableAdapter.update(row) Next row End if I'm sure it's something I'm over looking but I just can't see it. Thanks in advance, Joel

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  • Relation to multiple tables of different types for rating?

    - by Tronic
    i have a table structure like this Products Team Images and want to implement a rating/commenting-feature, where users can rate each entry of all tables. what's the best way to make a single rating table? e.g. a user votes a a product and a team entry, and it should be possible to get alle these entries from a single table. what kind of table-structure is best for this purpose? i hope, my questions is clear enough :/ thanks in advance!

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  • Getting highest results in a JOIN

    - by Keithamus
    I've got three tables; Auctions, Auction Bids and Users. The table structure looks something like this: Auctions: id title -- ----- 1 Auction 1 2 Auction 2 Auction Bids: id user_id auction_id bid_amt -- ------- ---------- ------- 1 1 1 200.00 2 2 1 202.00 3 1 2 100.00 Users is just a standard table, with id and user name. My aim is to join these tables so I can get the highest values of these bids, as well as get the usernames related to those bids; so I have a result set like so: auction_id auction_title auctionbid_amt user_username ---------- ------------- -------------- ------------- 1 Auction 1 202.00 Bidder2 2 Auction 2 100.00 Bidder1 So far my query is as follows: SELECT a.id, a.title, ab.bid_points, u.display_name FROM auction a LEFT JOIN auctionbid ab ON a.id = ab.auction_id LEFT JOIN users u ON u.id = ab.user_id GROUP BY a.id This gets the single rows I am after, but it seems to display the lowest bid_amt, not the highest.

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  • i tried to implement tde in sql2008...n got the error below.....plz help me to resolve...

    - by mahima
    while using USE mssqltips_tde; CREATE DATABASE ENCRYPTION KEY with ALGORITHM = AES_256 ENCRYPTION BY SERVER CERTIFICATE TDECert GO getting error Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'KEY'. Msg 319, Level 15, State 1, Line 3 Incorrect syntax near the keyword 'with'. If this statement is a common table expression or an xmlnamespaces clause, the previous statement must be terminated with a semicolon. please help in resolving the same as i need to implement Encryption on my DB

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