亲爱的所有错误代码如下：当子查询未引入EXISTS时，只能在选择列表中指定一个表达式。 [英] Dear all what is the error on below Code:Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

问题描述

亲爱的所有错误代码如下：当子查询未引入EXISTS时，只能在选择列表中指定一个表达式。

Dear all what is the error on below Code:Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

SELECT ID,firstName FROM human u WHERE fatherID IN(
                                    SELECT  ID,firstName FROM human h WHERE  fatherID IN
                                    (SELECT ID,firstName FROM human u WHERE ID = 2)
                                    )

我需要一个帮助

I NEED A HELP

推荐答案

您的子查询返回多个col UMN。它应该只返回一列。除此之外，我在这里看不到使用子查询的意义。这不应该给出你期望的结果：

Your sub query is returning more than one column. It should be returning only one column. That aside, I do not see a point of using sub query here. Shouldn't this give the result you expect:

SELECT ID, FIRSTNAME FROM HUMAN WHERE FATHERID=2

您还应该尝试阅读指南以提问。主题应该是精确的而不是整个问题本身。

You should also try and read guidelines to ask question. Subject should be precise and not entire question itself.

正确的查询是：

The proper query is:

SELECT ID, firstName
FROM human AS U WHERE U.ID = 2

我强烈建议您阅读一些教程，例如： http://www.w3schools.com/sql/ [ ^ ]

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