MySQL的語法問題

Question

爲什麼這工作完美：

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; 

但這並不：

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; 

，並沒有做到這一點：

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; 

無論是做這個的：

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; 

這是給我的問題存儲過程的一部分：

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返回沒事的時候，它應該返回40行。但是，如果我在@columnQuery中硬編碼「居民」這個詞，我會得到結果！是的，肯定有一張名爲「居民」的表。

有時候，我得到這個錯誤，有時我不知道，這取決於我是否使用CONCAT或只是手動連接字符串：

MySQL數據庫錯誤：你在你的SQL語法錯誤;檢查對應於你的MySQL服務器版本在1號線

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」正確的語法手冊試試這個：

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;