Question

在oracle中一条语句实现查询一张表统计字段a=1,b=1的个数(count(a),count(b))

Answer 1

select count(a) as coua from tab where a=1;
union all
select count(b) as coua from tab where b=1;
返回结果如下：
COUA
----------
1
1
第一行是 where a=1的，第二行就是 where b=1的，呵呵

Answer 2

Take it easy

SELECT SUM(CASE a WHEN 1 THEN 1 ELSE 0 END) AS cntA,
SUM(CASE b WHEN 1 THEN 1 ELSE 0 END) AS cntB
FROM tab

Answer 3

一楼的方法是正确的，很有创意