MySql官方手册学习笔记3―MySql中的存储过程简介_MySQL

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MySql官方手册学习笔记3—MySql中的存储过程简介 相关链接：MySql官方手册学习笔记1—MySql简单上手http:///database/201210/159522.html；MySql官方手册学习笔记2—MySql的模糊查询和正则表达式http:///database/201210/160095.html SELECT INTO CREATE PROCEDURE sp1 (x VARCHAR(5)) //创建储存过程 BEGIN DECLARE xname VARCHAR(5) DEFAULT 'bob'; //声明局部变量 DECLARE newname VARCHAR(5); DECLARE xid INT; SELECT xname,id INTO newname,xid //将查到的属性值存入变量中 FROM table1 WHERE xname = xname; SELECT newname; END; 变量名不能与列名一样，当这个程序被调用的时候，无论table.xname列的值是什么，变量newname将返回值‘bob’。 HANDLER mysql> CREATE TABLE test.t (s1 int,primary key (s1)); Query OK, 0 rows affected (0.00 sec) mysql> delimiter // //将定界符“;”改为“//”，因为程序中需要用到“;”。 mysql> CREATE PROCEDURE handlerdemo () -> BEGIN -> DECLARE insertErr CONDITION FOR SQLSTATE '23000'; //声明CONDITION -> DECLARE CONTINUE HANDLER FOR insertErr SET @x2 = 1;//声明HANDLER -> SET @x = 1; //为局部变量赋值 -> INSERT INTO test.t VALUES (1); -> SET @x = 2; -> INSERT INTO test.t VALUES (1); -> SET @x = 3; -> END; -> // Query OK, 0 rows affected (0.00 sec) mysql> CALL handlerdemo()// Query OK, 0 rows affected (0.00 sec) mysql> SELECT @x// +------+ | @x | +------+ | 3 | +------+ 1 row in set (0.00 sec) 注意到，@x是3，这表明MySQL被执行到程序的末尾。如果DECLARE CONTINUE HANDLER FOR insertErr SET @x2 = 1; 这一行不在，第二个INSERT因PRIMARY KEY强制而失败之后,MySQL可能已经采取 默认(EXIT)路径，并且SELECT @x可能已经返回2。 CURSOR CREATE PROCEDURE curdemo() BEGIN DECLARE done INT DEFAULT 0; DECLARE a CHAR(16); DECLARE b,c INT; DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1; DECLARE cur2 CURSOR FOR SELECT i FROM test.t2; DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1; OPEN cur1; //使用前先打开游标 OPEN cur2; REPEAT FETCH cur1 INTO a, b; FETCH cur2 INTO c; IF NOT done THEN IF b < c THEN INSERT INTO test.t3 VALUES (a,b); ELSE INSERT INTO test.t3 VALUES (a,c); END IF; END IF; UNTIL done END REPEAT; CLOSE cur1; CLOSE cur2; END CASE CASE case_value WHEN when_value THEN statement_list [WHEN when_value THEN statement_list] ... [ELSE statement_list] END CASE Or: CASE WHEN search_condition THEN statement_list [WHEN search_condition THEN statement_list] ... [ELSE statement_list] END CASE 存储程序的CASE语句实现一个复杂的条件构造。如果search_condition 求值为真，相应的SQL被执行。如果没有搜索条件匹配，在ELSE子句里的语句被执行。 LEAVE LEAVE label 这个语句被用来退出任何被标注的流程控制构造。它和BEGIN ... END或循环一起被使用。 ITERATE ITERATE label ITERATE只可以出现在LOOP, REPEAT, 和WHILE语句内。ITERATE意思为：“再次循环。” 例如： CREATE PROCEDURE doiterate(p1 INT) BEGIN label1: LOOP SET p1 = p1 + 1; IF p1 < 10 THEN ITERATE label1; END IF; LEAVE label1; END LOOP label1; SET @x = p1; END REPEAT mysql> delimiter // mysql> CREATE PROCEDURE dorepeat(p1 INT) -> BEGIN -> SET @x = 0; -> REPEAT SET @x = @x + 1; UNTIL @x > p1 END REPEAT; -> END -> // Query OK, 0 rows affected (0.00 sec) mysql> CALL dorepeat(1000)// Query OK, 0 rows affected (0.00 sec) mysql> SELECT @x// +------+ | @x | +------+ | 1001 | +------+ 1 row in set (0.00 sec) WHILE CREATE PROCEDURE dowhile() BEGIN DECLARE v1 INT DEFAULT 5; WHILE v1 > 0 DO ... SET v1 = v1 - 1; END WHILE; EN bitsCN.com