SQL Server枢轴是否为空？

使用：

SELECt pvt.Name    , isnull(pvt.[vocals], '') [vocals]    , isnull(pvt.[guitar], '') [guitar]    , isnull(pvt.[bass], '') [bass]    , isnull(pvt.[drums], '') [drums]FROM PivotSource  PIVOT(    max(tool)     FOR tool     IN ([vocals], [guitar], [bass], [drums]) ) pvt;

输出：

Name       vocals     guitar     bass       drums---------- ---------- ---------- ---------- ----------george     vocals     john       vocals     guitar     paul       vocals     bass       ringo      vocals     drumsroyi       vocals     guitar     yoko       vocals