Description: Replication table (only copy structure, source name: A new table name: b)
SQL: SELECT * INTO B from a where 1 <> 1
Description: Copy Table (copy data, source name: a target table name: b)
SQL: INSERT INTO B (A, B, C) SELECT D, E, F from B;
Description: Display article, author and last reply time
SQL: SELECT A.TITLE, A.USERNAME, B.Adddate from Table A, (Select Max (AddDDate) Addddate from Table Where Table.title = a.title) B
Description: Outer connection query (table name 1: a table name 2: b)
SQL: SELECT A.A, A.B, A.C, B.C, B.D, B.F from a left out join b on a.a = b.c
Description: Reminder in advance in advance
SQL: SELECT * FROM schedule Arranging WHERE DATEDIFF ('minute', f Start time, getdate ())> 5
Description: Two related tables, delete information that is already in the secondary table in the primary table
SQL:
Delete from info where not exists (Select * from infobz where info.infid = infobz.infid)
