MySQL--流程控制结构

CREATE FUNCTION test_if(score FLOAT) RETURNS CHAR
BEGIN
 DECLARE ch CHAR DEFAULT ‘A‘;
 IF score>90 THEN SET ch=‘A‘;
 ELSEIF score>80 THEN SET ch=‘B‘;
 ELSEIF score>60 THEN SET ch=‘C‘;
 ELSE SET ch=‘D‘;
 END IF;
 RETURN ch;
 
END $

SELECT test_if(87)$

CREATE PROCEDURE test_if_pro(IN sal DOUBLE)
BEGIN
 IF sal<2000 THEN DELETE FROM employees WHERE employees.salary=sal;
 ELSEIF sal>=2000 AND sal<5000 THEN UPDATE employees SET salary=salary+1000 WHERE employees.`salary`=sal;
 ELSE UPDATE employees SET salary=salary+500 WHERE employees.`salary`=sal;
 END IF;
 
END $

CALL test_if_pro(2100)$

CREATE FUNCTION test_case(score FLOAT) RETURNS CHAR
BEGIN 
 DECLARE ch CHAR DEFAULT ‘A‘;
 
 CASE   #------case块
 WHEN score>90 THEN SET ch=‘A‘;
 WHEN score>80 THEN SET ch=‘B‘;
 WHEN score>60 THEN SET ch=‘C‘;
 ELSE SET ch=‘D‘;
 END CASE;
 
 RETURN ch;
END $
SELECT test_case(56)$

DROP PROCEDURE pro_while1$
CREATE PROCEDURE pro_while1(IN insertCount INT)
BEGIN
 DECLARE i INT DEFAULT 1;
 WHILE i<=insertCount DO
  INSERT INTO admin(username,`password`) VALUES(CONCAT(‘Rose‘,i),‘666‘);
  SET i=i+1;
 END WHILE;
 
END $
CALL pro_while1(100)$

TRUNCATE TABLE admin $ 
DROP PROCEDURE test_while1 $ 
CREATE PROCEDURE test_while1 (IN insertCount INT) 
BEGIN
  DECLARE i INT DEFAULT 1 ;
  
   a:WHILE i<=insertCount DO
  INSERT INTO admin(username,`password`) VALUES(CONCAT(‘xiaohua‘,i),‘0000‘);
  IF i>=20 THEN LEAVE a;
  END IF;
  SET i=i+1;
 END WHILE a;
END $

CALL test_while1(100)$

TRUNCATE TABLE admin$
DROP PROCEDURE test_while1$
CREATE PROCEDURE test_while1(IN insertCount INT)
BEGIN
 DECLARE i INT DEFAULT 0;
 a:WHILE i<=insertCount DO
  SET i=i+1;
  IF MOD(i,2)!=0 THEN ITERATE a;
  END IF;
  
  INSERT INTO admin(username,`password`) VALUES(CONCAT(‘xiaohua‘,i),‘0000‘);
  
 END WHILE a;
END $

CALL test_while1(100)$