MySQL的语法问题

Question

为什么这工作完美：

SET @columnQuery = 'INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=''residents'' ORDER BY ORDINAL_POSITION;'; 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT; 

但这并不：

DECLARE TableName VARCHAR(50); 
SET @TableName = 'residents'; 

SET @columnQuery = 'INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=''' + @TableName + ''' ORDER BY ORDINAL_POSITION;'; 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT; 

，并没有做到这一点：

DECLARE TableName VARCHAR(50); 
SET @TableName = 'residents'; 

SET @columnQuery = CONCAT('INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=''', @TableName, ''' ORDER BY ORDINAL_POSITION;'); 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT; 

无论是做这个的：

SET @columnQuery = 'INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=? ORDER BY ORDINAL_POSITION;'; 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT USING @TableName; 

这是给我的问题存储过程的一部分：

CREATE PROCEDURE sp_ReturnSingleRowAsXml 
(
    IN TableName VARCHAR(50) 
) 
BEGIN 

DECLARE columnQuery VARCHAR(1000); 

DROP TABLE IF EXISTS ColumnNames; 

CREATE TEMPORARY TABLE ColumnNames (
    ID INT, ColumnName VARCHAR(50) 
); 

SET @columnQuery = 'INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=''' + @TableName + ''' ORDER BY ORDINAL_POSITION;'; 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT; 

select * from ColumnNames; 

END; 

CALL sp_ReturnSingleRowAsXml('residents'); 

的select返回没事的时候，它应该返回40行。但是，如果我在@columnQuery中硬编码“居民”这个词，我会得到结果！是的，肯定有一张名为“居民”的表。

有时候，我得到这个错误，有时我不知道，这取决于我是否使用CONCAT或只是手动连接字符串：

MySQL数据库错误：你在你的SQL语法错误;检查对应于你的MySQL服务器版本在1号线

Answer 1

我能得到它具有以下工作：

CREATE PROCEDURE `sp_ReturnSingleRowAsXml`( 
    IN TableName VARCHAR(50) 
) 
BEGIN 

DROP TABLE IF EXISTS ColumnNames; 

CREATE TEMPORARY TABLE ColumnNames ( 
    ID INT, ColumnName VARCHAR(50) 
); 
SET @tblName = TableName; 
SET @columnQuery = 'INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=? ORDER BY ORDINAL_POSITION;'; 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT USING @tblName; 

select * from ColumnNames; 

END 

Answer 2

使用近“NULL”正确的语法手册试试这个：

DECLARE TableName VARCHAR(50); 
SET @TableName = 'residents'; 

SET @columnQuery = 'INSERT INTO ColumnNames SELECT ORDINAL_POSITION, COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME=? ORDER BY ORDINAL_POSITION;'; 

PREPARE STMT FROM @columnQuery; 
EXECUTE STMT USING @TableName;