MySQL存储过程不以表名作为参数 [英] Mysql stored procedure don't take table name as parameter

问题描述

我已经写了一个存储过程.除了将表名作为输入参数外，它都工作正常.

I've written a stored procedure. It's working fine except taking the table name as input parameter.

让我们在MySQL中查看我的进程:

Let see my proc in MySQL:

DELIMITER $$
USE `db_test`$$

DROP PROCEDURE IF EXISTS test_proc$$

CREATE DEFINER=`root`@`localhost` 
PROCEDURE `test_proc`(IN serviceName VARCHAR(10),IN newsInfoTable VARCHAR(100))
BEGIN                  
    SELECT COUNT(*) FROM newsInfoTable WHERE newsServiceName=serviceName;           
END$$

DELIMITER ;

存储过程调用参数:

USE db_test;
CALL test_proc('abc','tbl_test_news');

在这里，服务名称参数可以正常工作.但是，如果我将newsInfoTable变量作为表输入参数，则会显示错误.

Here the service name parameter is working fine. But if I include the newsInfoTable variable as table input parameter then a error shows.

表'db_test.newsinfotable'不存在

Table 'db_test.newsinfotable' doesn't exist

为什么仅对表参数会发生这种情况?如何从此错误或

Why does this happen only for table parameter? How can I retrieve from this error or

如何将表名作为参数传递给存储过程?

How I pass a table name into a stored procedure as a parameter?

推荐答案

无法使用动态表名优化SP，因此许多数据库(包括MySQL)不允许动态指定表名.

An SP cannot be optimized with a dynamic table name, so many DBs, MySQL included, don't allow table names to be specified dynamically.

解决此问题的一种方法是使用动态SQL.

One way around this is to use Dynamic SQL.

CREATE DEFINER=`root`@`localhost` PROCEDURE `test_proc`(IN serviceName VARCHAR(10),IN newsInfoTable VARCHAR(100))
BEGIN                  
    SET @sql = CONCAT('SELECT COUNT(*) FROM ',newsInfoTable,' WHERE newsServiceName=?;'); 
    PREPARE s1 from @sql;
    SET @paramA = serviceName;
    EXECUTE s1 USING @paramA;
END$$

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