MySQL 9.0 Release Notes
        
      MySQL supports the IF,
      CASE,
      ITERATE,
      LEAVE
      LOOP,
      WHILE, and
      REPEAT constructs for flow control
      within stored programs. It also supports
      RETURN within stored functions.
    
      Many of these constructs contain other statements, as indicated by
      the grammar specifications in the following sections. Such
      constructs may be nested. For example, an
      IF statement might contain a
      WHILE loop, which itself contains a
      CASE statement.
    
      MySQL does not support FOR loops.