如何对SQL Server中的行进行计数

Question

如何在带有count的SQL中简单地切换带有列的行？ 有什么办法吗？ 实际上，我要与每个唯一的移动电话号码和产品名称并排排列，如果表中有两个移动电话号码，则计数= 2，并且这两个product1，product2并排显示在输出中。

即把这个结果：

Srno    Name| Mobile| Count  |  ProductName
1       xyz   1234       1       LNM
2       PQR   5678       1       VCD
3       xyz   1234       1       KLM
4       PQR   5678       1       NMG

到这个：

Srno    Name| Mobile| Count  |  ProductName1  | ProductName2 
1       xyz   1234       2       LNM              KLM
2       PQR   5678       2       VCD              NMG

Answer 1

如果您的product数量有限，则可以使用row_number()并进行条件聚合：

select min(srno) as srno, name, Mobile, count(*) as cnt,
       max(case when seq = 1 then ProductName end) as ProductName1,
       max(case when seq = 2 then ProductName end) as ProductName2
from (select t.*,
             row_number() over (partition by name, Mobile order by srno) as seq
      from table t
     ) t
group by name, Mobile;

Answer 2

尝试这个：

SET @row_number = 0;

SELECT 
    (@row_number:=@row_number + 1) AS Srno,
    T1.name,
    T1.Mobile,
    SUM(T1.xCount + T2.xCount) as cnt,
    max(T1.ProductName) as Product1,
    max(T2.ProductName) as Product2
FROM Table1 as T1
LEFT JOIN Table1 AS T2 ON T1.name = T2.name
                      AND T2.srno > T1.srno
GROUP BY T1.name, T1.Mobile
ORDER BY Srno