subquery

问题 i have an issue with query 1st table (Master) Name :MainCategory with fields (Category_id,Category_name) 2nd Table (Transation) Name : Incident with fields (Incident_id,Category_id,subject,description) i want to query to count the appearance of category_id in the table Transation for eg result can be Category_name Number_of_Faults Hardware 10 Software 22 Network 17 thanks Kumar 回答1: Try this: SELECT a.Category_Name, COUNT(b.Incident_Id) Number_of_Faults FROM MainCategory a JOIN Incident b ON

问题 In a MySql select statement involving aggregation, is it possible to select just the grouped by column without the aggregate? Basically I want to select IDs in subquery according to a criteria based on an aggregate, in this case the total payments to a client: select idclient, business_name from client where idclient in ( select idclient, sum(amount) as total from payment group by idclient having total > 100 ) ... but this fails with error Operand should contain 1 column(s) because the

问题 In a MySql select statement involving aggregation, is it possible to select just the grouped by column without the aggregate? Basically I want to select IDs in subquery according to a criteria based on an aggregate, in this case the total payments to a client: select idclient, business_name from client where idclient in ( select idclient, sum(amount) as total from payment group by idclient having total > 100 ) ... but this fails with error Operand should contain 1 column(s) because the

问题 In PostgreSQL, I have a table that, abstractly, looks like this: ╔═══╦═══╦═══╦═══╗ ║ A ║ B ║ C ║ D ║ ╠═══╬═══╬═══╬═══╣ ║ x ║ 0 ║ y ║ 0 ║ ║ x ║ 0 ║ x ║ 1 ║ ║ x ║ 1 ║ y ║ 0 ║ ║ x ║ 1 ║ z ║ 1 ║ ║ y ║ 0 ║ z ║ 0 ║ ║ y ║ 0 ║ x ║ 0 ║ ║ y ║ 1 ║ y ║ 0 ║ ╚═══╩═══╩═══╩═══╝ I want to transform it in a query into this: ╔═══╦═══╦══════╗ ║ A ║ B ║ D ║ ╠═══╬═══╬══════╣ ║ x ║ 0 ║ 1 ║ ║ x ║ 1 ║ null ║ ║ y ║ 0 ║ null ║ ║ y ║ 1 ║ 0 ║ ╚═══╩═══╩══════╝ …such that: The input table’s rows are grouped by A and B, and

问题 I've a simple table with an integer column: # setup table: create table t(x int); insert t select 1; The query select round(1.234, 1) from t returns 1.2 as expected. However, select round(1.234, x) from t returns 1.2000 . (It should return 1.2 , as per the docs.) Is this a bug? (Tested on version 5.5.10 and latest 5.6.24.) Or, is there any particular technical reason why columns cannot be used in the second argument of round ? How can we get round to work even while there are columns used in

问题 I am new to web programming and I'm trying to make a twitter-clone. At this point, I have 3 tables: users (id, name) id is the auto-generated id name of the user tweets (id, content, user_id) id is the auto-generated id content is the text of the tweet user_id is the id of the user that made the post followers (id, user_id, following_id) id is the auto-generated id user_id is the user who is doing the following following_id is the user that is being followed So, being new to sql as well, I am

问题 I have a page that displays a list of projects. With each project is displayed the following data retrieved from a mysqli database: Title Subtitle Description Part number (1 of x) The total number of photos associated with that project A randomly selected photo from the project A list of tags Projects are displayed 6 per page using a pagination system As this is based on an old project of mine, it was originally done with sloppy code (I was just learning and did not know any better) using

问题 I've this kind of delete query: DELETE FROM SLAVE_TABLE WHERE ITEM_ID NOT IN (SELECT ITEM_ID FROM MASTER_TABLE) Are there any way to optimize this? 回答1: You can use EXECUTE BLOCK for sequential scanning of detail table and deleting records where no master record is matched. EXECUTE BLOCK AS DECLARE VARIABLE C CURSOR FOR (SELECT d.id FROM detail d LEFT JOIN master m ON d.master_id = m.id WHERE m.id IS NULL); DECLARE VARIABLE I INTEGER; BEGIN OPEN C; WHILE (1 = 1) DO BEGIN FETCH C INTO :I; IF

问题 I am trying to figure out how to return the top 10 records for each group of Trans.TranSID. SELECT a.ABID, a.ABName, t.TranSID, SUM(IIF(TranTypeID = 'CO', td.Qty * CAST(td.Price AS money) * - 1, td.Qty * CAST(td.Price AS money))) AS TotalSales FROM Trans t INNER JOIN TransDetail td ON t.TranID = td.TranID INNER JOIN ABook a ON t.TranABID = a.ABID WHERE (t.TranDate BETWEEN CONVERT(DATETIME, '2012-01-01 00:00:00', 102) AND CONVERT(DATETIME, '2013-01-01 00:00:00', 102)) AND t.TranTypeID in ('SO'

问题 I am trying to figure out how to return the top 10 records for each group of Trans.TranSID. SELECT a.ABID, a.ABName, t.TranSID, SUM(IIF(TranTypeID = 'CO', td.Qty * CAST(td.Price AS money) * - 1, td.Qty * CAST(td.Price AS money))) AS TotalSales FROM Trans t INNER JOIN TransDetail td ON t.TranID = td.TranID INNER JOIN ABook a ON t.TranABID = a.ABID WHERE (t.TranDate BETWEEN CONVERT(DATETIME, '2012-01-01 00:00:00', 102) AND CONVERT(DATETIME, '2013-01-01 00:00:00', 102)) AND t.TranTypeID in ('SO'