mysql - 从 MySQL/oracle 中的多个表计数

Question

有4张表:A,B,C,D
有一个 id:4(input)
查询应该打印 id 在表中出现的次数

例如:

in table A id:4 occurs 5 times
in table B id:4 occurs 7 times
in table C id:4 occurs 3 times
in table D id:4 occurs 1 times

输出:

Table name       No of occurence

A                   5
B                   7
C                   3
D                   1

Answer 1

你可以尝试这样的事情:

select 'A', count(*) from a where id = 4
union all
select 'B', count(*) from b where id = 4
union all
select 'C', count(*) from c where id = 4
union all
select 'D', count(*) from d where id = 4