Question

sqlserver 在查询结果中统计相同行的行数

例如：表tab中信息为
ID pro
1 1
1 2
2 1
3 2
我想要的查询结果是
ID count
1 2
2 1
3 1

Answer 1

select ID, count(*) as Count from tab group by ID order by ID asc

Answer 2

select count(*) from tab where ID = 1