使用变量作为表名的mysql错误

Question

为什么我收到此错误？

CREATE DEFINER=`root`@`localhost` PROCEDURE `selectrecords`(tablename varchar(50))
begin
set @table_name=tablename;
set @sql_text=concat('Select * from @table_name');
prepare statement from @sql_text;
execute statement;
deallocate prepare statement;
end

错误:

....to use near '@table_name' at line 1

我的代码是正确的,但我不明白为什么....

Answer 1

我想你的意思是

CREATE PROCEDURE `selectrecords`(tablename varchar(50))
begin
    set @sql_text = concat('Select * from ', tablename);
    prepare statement from @sql_text;
    execute statement;
    deallocate prepare statement;
end

即使在动态SQL 中，您也无法参数化表名和列名，因此您唯一的选择就是与字符串连接。占位符中只能放置值。

• MySQL PREPARE 语法

更新1

CREATE PROCEDURE `selectrecords`(tablename varchar(50))
begin
    set @val = idnumber;
    set @sql_text = concat('Select * from ', tablename, ' WHERE id = ?');
    prepare statement from @sql_text;
    execute statement USING @val;
    deallocate prepare statement;
end