I have two tables that I count rows of them. For example;
Select count(*) FROM tbl_Events
Select count(*) FROM开发者_如何学C tbl_Events2
I need total count. How can I sum the result with a single statement?
select sum(cnt) from (
select count(*) as cnt from tbl_events
union all
select count(*) as cnt from tbl_events2
) as x
Try this:
SELECT (Select count(*) FROM tbl_Events) + (Select count(*) FROM tbl_Events2)
Or (tested in MSSQL), this:
SELECT COUNT(*)
FROM (SELECT * FROM tbl_Events
UNION ALL
SELECT * FROM tbl_Events2) AS AllEvents
I'd guess the first will lead to better performance because it has more obvious index options. Test to be sure, though.
Select Count(*)
From(
Select * From tbl_Events
Union All
Select * From tbl_Events2) as A
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