Can I do a mysql Select, Update and Delete in one query?

Question

Can I say that one of many ways to optimize mysql is to reduce the number of queries?

If that so, can I do this:

- Select \"data\" => $A from tabl         


        

Answer 1

NO,
only can combine

• DELETE and SELECT
• UPDATE and SELECT

This is not a proper way for mysql optimization simply
because each query come with different query cost.

And in myisam, it involve table level locking for write

Example for UPDATE and SELECT

/* this will update TABLE_A if ID in TABLE_B exist in TABLE_A */
UPDATE TABLE_A, TABLE_B
  SET TABLE_A.SOME_COLUMN=TABLE_B.SOME_COLUMN
WHERE TABLE_A.ID=TABLE_B.ID

/* or */
UPDATE TABLE_A
  SET SOME_COLUMN = (SELECT SOME_COLUMN_B FROM TABLE_B WHERE ... LIMIT 1)

Example for DELETE and SELECT

DELETE FROM TABLE_A WHERE TABLE_A IN(SELECT ID FROM TABLE_B)