我的查询应该在循环访问表table_a的游标时检查table_b中是否存在值。如果table_b中存在一个值,则将值返回到变量@yyy
当我运行这个存储过程时,我应该得到一个返回col2,col3,col1的值。但它只返回col2,col3
在此查询中,当我使用into @yyy
时,我觉得它无法正常工作。不确定是什么问题。能帮忙吗
只需删除into @yyy
即可获得正确的结果,但我需要对变量@yyy
进行更多更改,这就是我需要将结果存储到其中的原因。
Delimiter $$
DROP PROCEDURE IF EXISTS sp_test3;
CREATE PROCEDURE sp_test3()
BEGIN
DECLARE DONE INT DEFAULT 0;
DECLARE col1 varchar(255);
DECLARE curA CURSOR FOR SELECT a1 FROM table_a;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET DONE = 1;
OPEN curA;
SET @SQL_TXT = '';
while done = 0 do
fetch next from CurA into col1;
if done = 0 then
SET @xxx = CONCAT("select b1 into @yyy from table_b where b1 ='",
col1,"'");
PREPARE stmt_name FROM @xxx;
EXECUTE stmt_name;
DEALLOCATE PREPARE stmt_name;
SELECT @yyy;
END IF;
END WHILE;
close curA;
end
$$
在下面创建表脚本:
create table table_a(a1 varchar(255));
create table table_b(b1 varchar(255));
insert into table_a values('col2');
insert into table_a values('col3');
insert into table_a values('col5');
insert into table_a values('col1');
insert into table_b values('col2');
insert into table_b values('col3');
insert into table_b values('col4');
insert into table_b values('col1');
答案 0 :(得分:0)
drop procedure if exists sp_test3;
drop table if exists table_b, table_a;
create table if not exists table_a(a1 varchar(255));
create table if not exists table_b(b1 varchar(255));
insert into table_a values ('col2');
insert into table_a values ('col3');
insert into table_a values ('col5');
insert into table_a values ('col1');
insert into table_b values ('col2');
insert into table_b values ('col3');
insert into table_b values ('col4');
insert into table_b values ('col1');
CREATE PROCEDURE sp_test3()
BEGIN
DECLARE DONE, DONE1 INT DEFAULT 0;
DECLARE col1 varchar(255);
DECLARE curA CURSOR FOR SELECT a1 FROM table_a;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET DONE = 1;
OPEN curA;
SET @SQL_TXT = '';
while done = 0 do
fetch next from CurA into col1;
if done = 0 then
BEGIN
DECLARE CONTINUE HANDLER FOR NOT FOUND SET DONE1 = 1;
SET @xxx = CONCAT("select b1 into @yyy
from table_b
where b1 = '", col1, "'");
PREPARE stmt_name FROM @xxx;
EXECUTE stmt_name;
DEALLOCATE PREPARE stmt_name;
if (DONE1 = 0) THEN
SELECT @yyy;
ELSE
SET DONE1 = 0;
END IF;
END;
END IF;
END WHILE;
close curA;
end;