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  • Question on different ways to link tables

    - by dotnetdev
    What is the difference between linking two tables and then the PK is an FK in the other table, but the FK has not got the primary key option (so it does not have the gold key), and having the PK in one table as a PK in another table? Am I right to think that the second option is for a many-to-many relationship? Thanks

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  • Complex multiple join query across 3 tables

    - by Keir Simmons
    I have 3 tables: shops, PRIMARY KEY cid,zbid shop_items, PRIMARY KEY id shop_inventory, PRIMARY KEY id shops a is related to shop_items b by the following: a.cid=b.cid AND a.zbid=b.szbid shops is not directly related to shop_inventory shop_items b is related to shop_inventory c by the following: b.cid=c.cid AND b.id=c.iid Now, I would like to run a query which returns a.* (all columns from shops). That would be: SELECT a.* FROM shops a WHERE a.cid=1 AND a.zbid!=0 Note that the WHERE clause is necessary. Next, I want to return the number of items in each shop: SELECT a.*, COUNT(b.id) items FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid WHERE a.cid=1 GROUP BY b.szbid,b.cid As you can see, I have added a GROUP BY clause for this to work. Next, I want to return the average price of each item in the shop. This isn't too hard: SELECT a.*, COUNT(b.id) items, AVG(COALESCE(b.price,0)) average_price FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid WHERE a.cid=1 GROUP BY b.szbid,b.cid My next criteria is where it gets complicated. I also want to return the unique buyers for each shop. This can be done by querying shop_inventory c, getting the COUNT(DISTINCT c.zbid). Now remember how these tables are related; this should only be done for the rows in c which relate to an item in b which is owned by the respective shop, a. I tried doing the following: SELECT a.*, COUNT(b.id) items, AVG(COALESCE(b.price,0)) average_price, COUNT(DISTINCT c.zbid) FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid LEFT JOIN shop_inventory c ON c.cid=b.cid AND c.iid=b.id WHERE a.cid=1 GROUP BY b.szbid,b.cid However, this did not work as it messed up the items value. What is the proper way to achieve this result? I also want to be able to return the total number of purchases made in each shop. This would be done by looking at shop_inventory c and adding up the c.quantity value for each shop. How would I add that in as well?

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  • sql trigger inserting row into two tables

    - by allen
    I was looking for a way to create a trigger that would insert the same row into two tables with the same values. For example, a new row is inserted into pushNotificationQueue as soon as that is inserted, I would like that same exact row to be inserted into messages. I tried this CREATE TRIGGER add_to_messages after insert on mbb_pushNotificationQueue FOR EACH ROW insert into mbb_messages select * from mbb_pushNotificationQueue the only problem with that is that it goes through and adds entries that have already been previously added.

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  • Hash Tables - Java

    - by Antony
    Am about to do a homework, and i need to store quite a lot of information (Dictionary) in a data structure of my choice. I heard people in my classroom saying hash-tables are the way to go. How come?

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  • How to differenciate two tables

    - by Nemat
    Hi friends.... I have two tables.I want to get all records from one table that are different from the records in second table. For eg. if we have four records in first table like A,B,C,D and three records in second table thats A,B,C then the answer of query should be D. I have tried "EXCEPT" operator but it doesnt work fine.Kindly help me in writing correct query for the given problem. Any help is appreciated.... Thanks in Advance Nemat

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  • GROUP BY and SUM distinct date across 2 tables

    - by kenitech
    I'm not sure if this is possible in one mysql query so I might just combine the results via php. I have 2 tables: 'users' and 'billing' I'm trying to group summed activity for every date that is available in these two tables. 'users' is not historical data but 'billing' contains a record for each transaction. In this example I am showing a user's status which I'd like to sum for created date and deposit amounts that I would also like to sum by created date. I realize there is a bit of a disconnect between the data but I'd like to some all of it together and display it as seen below. This will show me an overview of all of the users by when they were created and what the current statuses are next to total transactions. I've tried UNION as well as LEFT JOIN but I can't seem to get either to work. Union example is pretty close but doesn't combine the dates into one row. ( SELECT created, SUM(status) as totalActive, NULL as totalDeposit FROM users GROUP BY created ) UNION ( SELECT created, NULL as totalActive, SUM(transactionAmount) as totalDeposit FROM billing GROUP BY created ) I've also tried using a date lookup table and joining on the dates but the SUM values are being added multiple times. note: I don't care about the userIds at all but have it in here for the example. users table (where status of '1' denotes "active") (one record for each user) created | userId | status 2010-03-01 | 10 | 0 2010-03-01 | 11 | 1 2010-03-01 | 12 | 1 2010-03-10 | 13 | 0 2010-03-12 | 14 | 1 2010-03-12 | 15 | 1 2010-03-13 | 16 | 0 2010-03-15 | 17 | 1 billing table (record created for every instance of a billing "transaction" created | userId | transactionAmount 2010-03-01 | 10 | 50 2010-03-01 | 18 | 50 2010-03-01 | 19 | 100 2010-03-10 | 89 | 55 2010-03-15 | 16 | 50 2010-03-15 | 12 | 90 2010-03-22 | 99 | 150 desired result: created | sumStatusActive | sumStatusInactive | sumTransactions 2010-03-01 | 2 | 1 | 200 2010-03-10 | 0 | 1 | 55 2010-03-12 | 2 | 0 | 0 2010-03-13 | 0 | 0 | 0 2010-03-15 | 1 | 0 | 140 2010-03-22 | 0 | 0 | 150 Table dump: CREATE TABLE IF NOT EXISTS `users` ( `created` date NOT NULL, `userId` int(11) NOT NULL, `status` smallint(6) NOT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1; INSERT INTO `users` (`created`, `userId`, `status`) VALUES ('2010-03-01', 10, 0), ('2010-03-01', 11, 1), ('2010-03-01', 12, 1), ('2010-03-10', 13, 0), ('2010-03-12', 14, 1), ('2010-03-12', 15, 1), ('2010-03-13', 16, 0), ('2010-03-15', 17, 1); CREATE TABLE IF NOT EXISTS `billing` ( `created` date NOT NULL, `userId` int(11) NOT NULL, `transactionAmount` int(11) NOT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1; INSERT INTO `billing` (`created`, `userId`, `transactionAmount`) VALUES ('2010-03-01', 10, 50), ('2010-03-01', 18, 50), ('2010-03-01', 19, 100), ('2010-03-10', 89, 55), ('2010-03-15', 16, 50), ('2010-03-15', 12, 90), ('2010-03-22', 99, 150);

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  • SQL Server: compare columns in two tables.

    - by maxt3r
    Hi, I've recently done a migration from a really old version of some application to the current version and i faced some problems while migrating databases. I need a query that could help me to compare columns in two tables. I mean not the data in rows, I need to compare the columns itself to figure out, what changes in table structure I've missed.

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  • MySQL Joining three tables

    - by text
    I am doing a query with three tables, the problem was one table has many occurrences of id of another. sample data: users: id answers: id:1 user_answer :1 id:1 user_answer :2 id:1 user_answer :3 Questions: id:1 answers :answer description id:2 answers :answer description id:3 answers :answer description How can I get all user information and all answer and its description, I used GROUP by user.id but it only returns only one answer. I want to return something like this list all of users answer: Name Q1 Q2 USERNAME ans1,ans2 ans1,ans2 comma separated description of answer here

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  • MySQL: Insert into multiple tables in same query with BEGIN&COMMIT

    - by strc
    I want to insert into multiple tables in same query by using BEGIN and COMMIT. It seems the error occur at begin. here is my SQL command BEGIN INSERT INTO Product (pName, pBrand, pCategory, pSize, pQuantity, pPrice, pDetail) VALUES('$name', '$brand', '$category', '$size', '$quantity', '$price', '$detail') INSERT INTO Image (iName, iExt, iSize, pID) VALUES('$img_name', '$img_ext', '$img_size', LAST_INSERT_ID()); COMMIT;

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  • How to differentiate two tables

    - by Nemat
    I have two tables and I want to get all records from one table that are different from the records in second table. Eg.: if we have four records in the first table like A,B,C,D and three records in the second table thats A,B,C then the answer of query should be D. I have tried "EXCEPT" operator but it doesn't work fine. Kindly help me in writing correct query for the given problem.

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  • Need a MYSQL query to compare two tables and only output non matching results

    - by ee12csvt
    I have two tables in my database, one contains a list of items with other information on these items. The other table is contains a list of photographs of these items. The items table gives each item a unique identifier,which is used in the photographs table to identifier which item has been photographed. I need to output a list of items that are not linked to a photograph in the second table. Any ideas on how I can do this?

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  • join two tables but want one matching columns instead of showing it separately sql server 2008

    - by amby
    Hi i want to display join result of two tables but don't want to show matching column separately. I want it one instead of two. so please tell me what query should i use for this. I m using sql server 2008 and my query is like: select * from Customer_Order, optRelation where Customer_Order.orderNumber = optRelation.orderNumber AND optRelation.orderNumber = 21. please reply soon

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  • Merging some columns of two mysql tables where id = fileid

    - by garg
    There are two tables TableA filedata_id | user_id | filename 1 | 1 | file.txt 2 | 1 | file2.txt TableB a_id | date | filedataid | counter | state | cat_id | subcat_id | med_id 99 | 1242144 | 1 | 2 | v | 55 | 56 | 90 100 | 1231232 | 2 | 3 | i | 44 | 55 | 110 I want to move columns cat_id, subcat_id, med_id to TableA where tableA.filedata_id = TableB.filedataid The result should be: TableA filedata_id | user_id | filename | cat_id | subcat_id | med_id 1 | 1 | file.txt | 55 | 56 | 90 2 | 1 | file2.txt | 44 | 55 | 110 and so on. Is there a way to do this easily?

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  • Select a record with highest amount by joining two tables

    - by user2516394
    I've 2 tables Sales & Purchase, Sales table with fields SaleId, Rate, Quantity, Date, CompanyId, UserID. Purchase table with fields PurchaseId, Rate, Quantity, Date, CompanyId, UserID. I want to select a record from either table that have highest Rate*Quantity. SELECT SalesId Or PurchaseId FROM Sales,Purchase where Sales.UserId=Purchase.UserId and Sales.CompanyId=Purchase.CompanyId AND Sales.Date=Current date AND Purchase.Date=Current date AND Sales.UserId=1 AND Purchase.UserId=1 AND Sales.CompanyId=1 AND Purchase.ComoanyId=1

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  • sql count() query for tables

    - by air
    i have two tables table1 fields fid,fname,fage a ,abc ,20 b ,bcv ,21 c ,cyx ,19 table2 fields rcno,fid,status 1 ,a ,ok 2 ,c ,ok 3 ,a ,ok 4 ,b ,ok 5 ,a ,ok i want to display rectors like this fid from table1 , count(recno) from table 2 and fage from table1 fid,count(recno),fage a ,3 ,20 b ,2 ,21 c ,1 ,19 i try many sql queries but got error Thanks

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  • How to create HTML tables from MySQL?

    - by Chris
    Hi Guys, I'm building a part of a system where the user can define "views" from a mysql database. I want some way of generating simple HTML tables/reports from the data, but not just plain output of sql queries- simple joins probably isn't enough. Any ideas?

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