mysql 动态游标
这是我编写的程序 - Cursors c1 & c2。 c2 在 c1 内部，我尝试在 c1 下面声明 c2 （在 c1 之外）光标），但随后 I 没有采用更新后的值:(任何使其正常工作的建议都会有所帮助，谢谢
create table t1(i int);
create table t2(i int, j int);
insert into t1(i) values(1), (2), (3), (4), (5);
insert into t2(i, j) values(1, 6), (2, 7), (3, 8), (4, 9), (5, 10);
delimiter $
CREATE PROCEDURE p1()
BEGIN
DECLARE I INT;
DECLARE J INT;
DECLARE done INT DEFAULT 0;
DECLARE c1 CURSOR FOR SELECT i FROM t1;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN c1;
REPEAT
FETCH c1 INTO I;
IF NOT done THEN
select I;
DECLARE c2 CURSOR FOR
SELECT j FROM t2 WHERE i = I;
OPEN c2;
REPEAT
FETCH c2 into J;
IF NOT done THEN
SELECT J;
END IF;
UNTIL done END REPEAT;
CLOSE c2;
set done = 0;
END IF;
UNTIL done END REPEAT;
CLOSE c1;
END$
delimiter ;
Here is the procedure I wrote- Cursors c1 & c2. c2 is inside c1, I tried declaring c2 below c1 (outside the c1 cursor) but then I is NOT taking the updated value :( Any suggestions to make it working would be helpful, Thanks
create table t1(i int);
create table t2(i int, j int);
insert into t1(i) values(1), (2), (3), (4), (5);
insert into t2(i, j) values(1, 6), (2, 7), (3, 8), (4, 9), (5, 10);
delimiter $
CREATE PROCEDURE p1()
BEGIN
DECLARE I INT;
DECLARE J INT;
DECLARE done INT DEFAULT 0;
DECLARE c1 CURSOR FOR SELECT i FROM t1;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN c1;
REPEAT
FETCH c1 INTO I;
IF NOT done THEN
select I;
DECLARE c2 CURSOR FOR
SELECT j FROM t2 WHERE i = I;
OPEN c2;
REPEAT
FETCH c2 into J;
IF NOT done THEN
SELECT J;
END IF;
UNTIL done END REPEAT;
CLOSE c2;
set done = 0;
END IF;
UNTIL done END REPEAT;
CLOSE c1;
END$
delimiter ;
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评论（1）
我不明白你想做什么。当您在过程中一次选择一个字段时，您将创建多个结果集。我怀疑这就是你想要的。
以下过程要简单得多，并在单个结果集中为您提供相同的数据：
也许您可以编辑您的问题并描述您想要的结果，或者显示所需输出的示例。
I don't understand what you are trying to do. When you select individual fields one at a time in a procedure, you're creating multiple result sets. I doubt that's what you want.
The following procedure is far simpler and gives you the same data in a single result set:
Perhaps you could edit your question and describe what result you want, or show an example of the desired output.