SQL commands use simple records

Half a month ago, I wanted to write down the SQL commands I used!!!

Topics: Query by Time: 41863349 Left Association: SELECT * FROM Uesrs-time_entries to "on users. ' id ' = time_entries. ' users_id '-user table associated timesheets minus the same value: s Elect DISTINCT * from Uesrs left joins time_entries on users. ' id ' = time_entries. ' users_id '-query followed by DISTINCT display merge two columns: CONCAT delete Except for table rows: Delete from email_addresses where email_addresses. ' ID ' =56-the specified ID deletes the change table data: UPDATE tb3 SET tb3. ' id ' =5 where tb3. ' Username ' = ' Zhang San '-Change tb3 table, name ' Zhang San ', change ID number to 5

SQL commands use simple records