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
SELECT (
SELECT COUNT(*)
FROM tab1
) AS count1,
(
SELECT COUNT(*)
FROM tab2
) AS count2
FROM dual
其他回答
select (select count(*) from tab1) count_1, (select count(*) from tab2) count_2 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)
只是因为它略有不同:
SELECT 'table_1' AS table_name, COUNT(*) FROM table_1
UNION
SELECT 'table_2' AS table_name, COUNT(*) FROM table_2
UNION
SELECT 'table_3' AS table_name, COUNT(*) FROM table_3
它给出了转置的答案(每个表一行而不是一列),否则我不认为它有多大不同。我认为在性能方面,它们应该是相等的。
SELECT (
SELECT COUNT(*)
FROM tab1
) AS count1,
(
SELECT COUNT(*)
FROM tab2
) AS count2
FROM dual
选择 (select count() from tab1 where field like 'value') + (select count() from tab2 where field like 'value') 数