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MySQL 8.3 Reference Manual
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15.6.6 游标

MySQL支持存储程序中的游标。语法与嵌入式SQL相同。游标具有以下属性:

  • Asensitive:服务器可能或不可能复制其结果表

  • 只读:不可更新

  • 不可滚动:只能在一个方向上遍历,不能跳过行

游标声明必须出现在处理程序声明之前,变量和条件声明之后。

示例:

CREATE PROCEDURE curdemo()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  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 NOT FOUND SET done = TRUE;

  OPEN cur1;
  OPEN cur2;

  read_loop: LOOP
    FETCH cur1 INTO a, b;
    FETCH cur2 INTO c;
    IF done THEN
      LEAVE read_loop;
    END IF;
    IF b < c THEN
      INSERT INTO test.t3 VALUES (a,b);
    ELSE
      INSERT INTO test.t3 VALUES (a,c);
    END IF;
  END LOOP;

  CLOSE cur1;
  CLOSE cur2;
END;