我如何从两个不同的表(叫他们tab1和tab2)选择计数(*)有作为结果:
Count_1 Count_2
123 456
我试过了:
select count(*) Count_1 from schema.tab1 union all select count(*) Count_2 from schema.tab2
但我所拥有的只有:
Count_1
123
456
我如何从两个不同的表(叫他们tab1和tab2)选择计数(*)有作为结果:
Count_1 Count_2
123 456
我试过了:
select count(*) Count_1 from schema.tab1 union all select count(*) Count_2 from schema.tab2
但我所拥有的只有:
Count_1
123
456
当前回答
因为我找不到其他答案了。
如果你不喜欢子查询并且在每个表中都有主键,你可以这样做:
select count(distinct tab1.id) as count_t1,
count(distinct tab2.id) as count_t2
from tab1, tab2
但是就性能而言,我认为Quassnoi的解决方案更好,也是我会使用的解决方案。
其他回答
SELECT (
SELECT COUNT(*)
FROM tab1
) AS count1,
(
SELECT COUNT(*)
FROM tab2
) AS count2
FROM dual
Declare @all int
SET @all = (select COUNT(*) from tab1) + (select count(*) from tab2)
Print @all
or
SELECT (select COUNT(*) from tab1) + (select count(*) from tab2)
select
t1.Count_1,t2.Count_2
from
(SELECT count(1) as Count_1 FROM tab1) as t1,
(SELECT count(1) as Count_2 FROM tab2) as t2
SELECT (
SELECT COUNT(*)
FROM tbl1
)
+
(
SELECT COUNT(*)
FROM tbl2
)
as TotalCount
select (select count(*) from tab1) count_1, (select count(*) from tab2) count_2 from dual;