mysql - Mysql存储过程动态选择没有变量

Question

当我没有使用 out 变量时，存储过程可以正常工作，但是当我使用 out 变量执行存储过程时，会出现以下错误：

MySQL 说：#1327 - 未声明的变量：sp_result

代码：

CREATE DEFINER=`root`@`localhost` PROCEDURE `test3`(OUT `sp_result` INT(11), IN `sp_where_param` VARCHAR(100), IN `sp_where_value` VARCHAR(100), IN `sp_table_name` VARCHAR(100))
NO SQL
BEGIN
DECLARE tbl_id VARCHAR(100);

SET tbl_id = CONCAT(sp_table_name,'_id');

SET @temp1=CONCAT('SELECT count(',tbl_id,') INTO sp_result FROM ',sp_table_name,' WHERE ',sp_where_param,' = \'',sp_where_value,'\'');
PREPARE stmt1 FROM @temp1;
EXECUTE stmt1;

END

也许没有输出变量也不起作用:(

Answer 1

尝试使用用户变量 -

CREATE DEFINER = 'root'@'localhost'
PROCEDURE test3 (OUT `sp_result` int(11), IN `sp_where_param` varchar(100), IN `sp_where_value` varchar(100), IN `sp_table_name` varchar(100))
NO SQL
BEGIN
  DECLARE tbl_id varchar(100);

  SET tbl_id = CONCAT(sp_table_name, '_id');

  SET @temp1 = CONCAT('SELECT COUNT(', tbl_id, ') INTO @sp_result FROM ', sp_table_name, ' WHERE ', sp_where_param, ' = \'', sp_where_value, '\'');

  PREPARE stmt1 FROM @temp1;
  EXECUTE stmt1;
  DEALLOCATE PREPARE stmt1;

  set sp_result = @sp_result;

END

...并添加 DEALLOCATE PREPARE 语句。

Answer 2

它应该是-

SET tbl_id = CONCAT(sp_table_name,'_id');
SET @temp1=CONCAT('SELECT count(',tbl_id,') INTO

像这样

SET @tbl_id:= CONCAT(sp_table_name,'_id');
SET @temp1:=CONCAT('SELECT count(',tbl_id,') INTO