Question

以下查询有效。我想替换字面值＆＃34; 2＆＃34;在列号为P0.TLKP_Parent的最内层查询中。当我这样做时，我得到一个语法错误：

错误代码：1054。未知列＆＃39; P0.TLKP_Parent_PK＆＃39;在＆＃39; where子句＆＃39;

SELECT p0.*,x.nm
From t_child P0
,
(
    SELECT p1.nm
    FROM   mydb.tlkp_parent P1 
    where  p1.lang_cd="FR"
    AND 
    p1.CORE_VAL= 
    (
        select CORE_VAL 
        FROM   mydb.tlkp_parent P2 WHERE 
        (p2.PK =2) '<== want the '2' to be replaced with P0.TLKP_Parent
    )
) as x
where P0.TLKP_Parent_PK=2

如何解决这个问题？有没有更好的方法来编写此查询？

感谢。注意：DDL：

DROP TABLE IF EXISTS t_child;

CREATE TABLE t_child (
  Seq_id int(11) NOT NULL AUTO_INCREMENT,
  SomeData varchar(45) DEFAULT NULL,
  TLKP_Parent_PK int(11) NOT NULL,
  PRIMARY KEY (Seq_id),
  KEY fk_t_Child_TLKP_Parent_idx (TLKP_Parent_PK)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS tlkp_parent;

CREATE TABLE tlkp_parent (
  PK int(11) NOT NULL,
  Core_Val int(11) DEFAULT NULL,
  Lang_Cd char(2) DEFAULT NULL,
  nm varchar(45) DEFAULT NULL,
  PRIMARY KEY (PK)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO tlkp_parent
(PK, Core_Val, Lang_Cd, nm) VALUES
(1,100,'EN', 'A in English'),
(2,101,'EN', 'B in English'),
(3,102,'EN', 'C in English'),
(4,100,'FR', 'A in French'),
(5,101,'FR', 'B in French'),
(6,102,'FR', 'C in French');

INSERT INTO `t_child`
( Seq_id, `SomeData`, `TLKP_Parent_PK`) VALUES 
(1, 'some data for Bed',2),
(2, 'some data for Couch',2);

Answer 1

问题是P0无法识别表SELECT，因为它不属于inner join，请尝试以下操作：

SELECT p0.*, (SELECT p1.nm
    FROM   mydb.tlkp_parent P1 
    where  p1.lang_cd="FR"
    AND 
    p1.CORE_VAL= 
    (
        select CORE_VAL 
        FROM   mydb.tlkp_parent P2 WHERE 
        (p2.PK =P0.TLKP_Parent_PK)
    )) as nm
    FROM t_child P0
where P0.TLKP_Parent_PK=2

Answer 2

我无法真正看到您的查询与此之间的区别：

SELECT c.*
     , y.nm 
  FROM t_child c 
  JOIN tlkp_parent x 
    ON x.pk = c.tlkp_parent_pk 
  JOIN tlkp_parent y 
    ON y.core_val = x.core_val 
 WHERE y.lang_cd = 'FR';

正确的方式来执行相关

2 个答案: