如何将两个查询的结果与排序相结合？

Question

你如何加入2个查询的结果,按日期排序？

SELECT * FROM table1 WHERE tag='1'
SELECT * FROM table2 WHERE tag='3'

table1,table2具有相同的字段: id|article|author|tag|date

PS:按方式,标记IS workid

Answer 1

您可以使用UNION ALL从两个表中获取行:

SELECT id, article, author, tag, date FROM table1 WHERE tag = '1'
UNION ALL
SELECT id, article, author, tag, date FROM table2 WHERE tag = '3'
ORDER BY date

您可能还需要考虑重构数据库,以便不使用两个表而只使用带有字段的单个表来区分每行的类型.然后查询可以简化为:

SELECT id, article, author, tag, date
FROM yourtable
WHERE (tag, type) IN (('1','type1'), ('3','type2'))
ORDER BY date

Answer 2

SELECT * 
FROM   (SELECT * 
        FROM   table1 
        UNION 
        SELECT * 
        FROM   table2) t 
ORDER  BY t.DATE