Good mysql multi-table join query _ MySQL

Nice mysql Union table multi-table query bitsCN.com

Good mysql multi-table query

For mysql multi-table queries, you can directly select * from tablea as a, tableb. as B where. cc = B. cc. today, I will share a novel way of writing, and the execution efficiency of hundreds of thousands of data is quite fast. Here are some statements for multi-table queries:

SQL code

# Information about QQ invitations for deleting illegal credit data from Tbl_User

Delete from Tbl_User where FQQ IN

(Select FDesQQ from Tbl_InviteHistory where FSrcQQ IN

(Select DISTINCT (FSrcQQ) from Tbl_ScoreDetail where FScore> '20180101' and FStrategy = '4 '))

# Delete QQ information of illegal credit data from Tbl_User

Delete from Tbl_User where FQQ IN

(Select DISTINCT (FSrcQQ) from Tbl_ScoreDetail where FScore> '20180101' and FStrategy = '4 ')

# Delete the invitation records for all invalid points in Tbl_InviteHistory

Delete from Tbl_InviteHistory where FSrcQQ IN

(Select DISTINCT (FSrcQQ) from Tbl_ScoreDetail where FScore> '20180101' and FStrategy = '4 ')

# Delete the total points of invalid points in Tbl_Score

Delete from Tbl_Score where FQQ IN

(Select DISTINCT (FSrcQQ) from Tbl_ScoreDetail where FScore> '20180101' and FStrategy = '4 ')

# Delete invalid points in Tbl_ScoreDetail

Delete from Tbl_ScoreDetail where FScore> '2013' and FStrategy = '4'

# Delete users without Tbl_User in the Tbl_Score table

Delete from Tbl_Score where FQQ not IN (select FQQ from Tbl_User)

Delete from Tbl_ScoreDetail where FSrcQQ not IN (select FQQ from Tbl_User)

// Query the user list with a redemption code greater than 20

Select fqq, FCode, FApplyTime FROM Tbl_Code where FQQ in (SELECT. fqq from (select count (*) as num, fqq from 'tbl _ code' group by fqq having num> 20) as a) and FStatus = '1'

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