[英]MySQL - Rename selected columns with the same name from two different tables
我正在从两个不同的表中选择同一列,但要使用select as
使其具有不同的名称。
(SELECT letter AS letter_1, sex AS sex_1 FROM `celebs_a` LIMIT 1)
UNION
(SELECT letter AS letter_2, sex AS sex_2 FROM `celebs_b` LIMIT 1)
该查询返回以下内容:
letter_1 sex_1
a 1
b 1
但是,我希望它返回以下内容:
letter_1 letter_2 sex_1 sex_2
a b 1 1
如何使该查询将每个值作为不同的列名返回? 谢谢。
尝试这个:
SELECT
(SELECT letter AS letter_1 FROM `celebs_a` LIMIT 1) AS letter_1,
(SELECT letter AS letter_2 FROM `celebs_b` LIMIT 1) AS letter_2;
更新:
SELECT
(SELECT letter ... FROM celebs_a ...) AS letter_1,
(SELECT letter ... FROM celebs_b ...) AS letter_2,
(SELECT sex ... FROM celebs_a ...) AS sex_1,
(SELECT sex ... FROM celebs_b ...) AS sex_2
否则,Barmars的方法会更好(它仅运行2个SELECT查询)
SELECT MAX(letter_1) AS letter_1, MAX(sex_1) AS sex_1,
MAX(letter_2) AS letter_2, MAX(sex_2) AS sex_2
FROM (
(SELECT letter AS letter_1, '' AS letter_2, sex AS sex_1, 0 AS sex_2
FROM celebs_a
LIMIT 1)
UNION
(SELECT '' AS letter_1, letter AS letter_2, 0 AS sex_1, sex AS sex_2
FROM celebs_b
LIMIT 1)
) AS derived_table_must_have_an_alias
您可以轻松地将其扩展为从每个表中选择多个列。 只需将0
或''
用作其他表中这些列的占位符即可。
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