Question

我有一个类似的查询：

SELECT COUNT(DISTINCT `ID`) FROM db1.table UNION ALL SELECT COUNT(DISTINCT `ID`) FROM db2.table

我的真实查询更复杂，我有LEFT JOIN和多个条件等...

此查询返回给我一个包含2个结果的数组：Count 1和Count 2

我怎样才能返回一个结果？ Count 1 + Count 2？

谢谢！

Answer 1

试试这个：

SELECT (SELECT COUNT(DISTINCT `ID`) FROM db1.table) + 
       (SELECT COUNT(DISTINCT `ID`) FROM db2.table)

如果您还想单独返回db1，db2个计数，请使用此查询：

SELECT countDb1, countDb2, countDb1 + countDb2 AS total
FROM (
SELECT (SELECT COUNT(DISTINCT `ID`) FROM db1.table) AS countDb1,
       (SELECT COUNT(DISTINCT `ID`) FROM db2.table) AS countDb2) AS t

选择Count with Distinct和Union All

1 个答案: