分页查询超时问题(1)
<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">晚上割接了1500万联系人账号到EI_LinkmanUserInfos表，第二天程序报告下面的查询语句超时</span>
;WITH a AS (
SELECT ROW_NUMBER() OVER(ORDER BY l.LinkmanId) AS LinkmanCount,
l.LinkmanId,l.Name,l.LinkmanType
,l.Mobile,l.Email,l.DepartmentId,d.Name AS DepartmentName,l.Position,l.Code AS VnetCode
FROM dbo.EI_Linkmen l
LEFT JOIN dbo.EI_Departments d ON l.DepartmentId=d.DepartmentId
left join (SELECT * FROM (
SELECT ROW_NUMBER() OVER(PARTITION BY LinkmanId ORDER BY LinkmanUserInfoId) AS rn,*
FROM dbo.EI_LinkmanUserInfos ) uix WHERE uix.rn=1) ui on l.LinkmanId=ui.linkmanid
WHERE l.DataStatus = 0 AND l.EnterpriseId=916627 )
SELECT (SELECT COUNT(1) FROM a ) AS TotalCount,LinkmanId,Name,Mobile,Email,DepartmentId,DepartmentName,LinkmanType
as [Type],Position,OpenContent='',VnetCode
FROM a WHERE LinkmanCount BETWEEN 1 AND 10
分析：
1、查询中左连接了EI_LinkmanUserInfos表，但是查询的结果列表中没有包含EI_LinkmanUserInfos表的任何字段。
2、where条件中只包含对表EI_LinkMen表的过虑l.DataStatus = 0 AND l.EnterpriseId=916627,并且EI_Departments.departmentID是主键，这种情况下应该先对EI_LinkMen分页，再去关联EI_Departments。
SQL语句改成先分页，再查询关联信息：
;with a as(
select ROW_NUMBER() OVER(ORDER BY l.LinkmanId) AS LinkmanCount, l.LinkmanId,l.Name,l.LinkmanType
,l.Mobile,l.Email,l.DepartmentId,l.Position,l.Code AS VnetCode
from ei_linkmen l
where DataStatus=0 and EnterpriseId=916627
)
select (SELECT COUNT(1) FROM a ) AS TotalCount,l.LinkmanId,l.Name,Mobile,Email,l.DepartmentId
,d.Name DepartmentName,LinkmanType,x.AccountName,x.AccountECcode
from a l
LEFT JOIN dbo.EI_Departments d ON l.DepartmentId=d.DepartmentId
outer apply(select top 1 * from EI_LinkmanUserInfos where LinkmanId=l.LinkmanId order by LinkmanUserInfoId) x
where LinkmanCount BETWEEN 1 AND 10