sql if

SELECT a.id, a.EduSiteNo, a.EduSiteName, a.SchoolId, a.LinkMan, a.Tel, a.Mobile, a.Fax, a.Address,
CASE a.EduSiteType WHEN 0 THEN '自有' ELSE '租赁' END AS EduSiteType, a.ContractBegin, a.ContractEnd, a.EduSiteState, a.Remark, a.PlaceSize, a.IsDelete,
b.CodeValue AS Area
FROM dbo.EduSite AS a LEFT OUTER JOIN
dbo.DictionaryChild AS b ON a.Area = b.id AND a.IsDelete = 0 AND b.IsDelete = 0 AND b.CodeId = '2570986E-E6A5-452E-8845-7EA9CB1366A2'