MySQL Union合并查询数据及表别名、字段别名用法分析

本文实例讲述了MySQL Union合并查询数据及表别名、字段别名用法。分享给大家供大家参考，具体如下：

union关键字

SELECT s_id, f_name, f_priceFROM fruitsWHERE f_price < 9.0UNION ALLSELECT s_id, f_name, f_priceFROM fruitsWHERE s_id IN(101,103);

SELECT * from orders AS oWHERE o.o_num = 30001;

SELECT f1.f_name AS fruit_name, f1.f_price AS fruit_priceFROM fruits AS f1WHERE f1.f_price < 8;

SELECT s_id, f_name, f_priceFROM fruitsWHERE f_price < 9.0UNION ALLSELECT s_id, f_name, f_priceFROM fruitsWHERE s_id IN(101,103);

SELECT s_id, f_name, f_priceFROM fruitsWHERE f_price < 9.0UNION ALLSELECT s_id, f_name, f_priceFROM fruitsWHERE s_id IN(101,103);

SELECT * from orders AS oWHERE o.o_num = 30001;

SELECT c.c_id, o.o_numFROM customers AS c LEFT OUTER JOIN orders AS oON c.c_id = o.c_id;

SELECT f1.f_name AS fruit_name, f1.f_price AS fruit_priceFROM fruits AS f1WHERE f1.f_price < 8;

如果没有对连接后的值取别名，其显示列名称将会不够直观，输入如下SQL

SELECT CONCAT(RTRIM(s_name) , ' (', RTRIM(s_city), ')')FROM suppliersORDER BY s_name;

希望本文所述对大家MySQL数据库计有所帮助。

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