未知列错误

Question

这个SQL失败：

select * from RRICallouts as r 
    JOIN LevelToCalloutsJT as lc on (`r.__kp_RecID` = `lc._kf_RecID~Callout`) 
    JOIN Levels as l ON (`lc._kf_RecID~Level` = `l.__kp_RecID`) 
    where `l.__kp_RecID` = 201006221644060009 

#1054 - Unknown column 'l.__kp_RecID' in 'where clause 

这工作：

select `__kp_RecID` from Levels as l ; 

在某些Linux变种

Answer 1

的问题是在使用MySQL 5.0.77你的反应。

`r`.`__kp_RecID` 

...而不是：

`r.__kp_RecID` 

测试用例：你应该按如下方式使用它们

CREATE TABLE test (id int, value int); 
INSERT INTO test VALUES (1, 100); 

SELECT `t`.`id` FROM test AS t; 
+------+ 
| id | 
+------+ 
| 1 | 
+------+ 
1 row in set (0.00 sec) 

SELECT `t.id` FROM test AS t; 
ERROR 1054 (42S22): Unknown column 't.id' in 'field list'