SQL -基于特定列选择distinct

Question

我的SQL有点生疏，所以请容忍我。

我有一个疑问，联合，两个选择不同的语句，从不同的来源。来自两个select语句的数据重叠，但每个语句都提取一个日期列，该列并不总是填充，这取决于源。

我试图找到一种方法来删除这两个语句之间的重复记录，而忽略日期列。

与之一样，如果两个或多个记录具有相同的PCName、供应商、产品和版本，则不管日期列如何，都会筛选其中一个记录。

SELECT DISTINCT 
   SYS.Netbios_Name0 as PCName,
   ARP.Publisher0 as Vendor,
   ARP.DisplayName0 as Product,
   ARP.Version0 as Version,
   replace(replace(convert(varchar,ARP.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate,
   replace(replace(convert(varchar,ARP.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate2
FROM v_Add_Remove_Programs ARP
JOIN v_R_System SYS 
  ON ARP.ResourceID=SYS.ResourceID
WHERE SYS.Netbios_Name0 like 'CH-%' and InstallDate0 NOT LIKE ''

UNION

Select DISTINCT 
    SYS.Netbios_Name0 as PCName,
    SP.CompanyName as Vendor, 
    SP.ProductName as Product, 
    SP.ProductVersion as Version,
    replace(replace(convert(varchar,MARP.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate,
    replace(replace(convert(varchar,GSI.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate2
FROM v_GS_SoftwareProduct SP
JOIN v_R_System SYS 
  ON SP.ResourceID=SYS.ResourceID

LEFT JOIN v_GS_Mapped_Add_Remove_Programs MARP
  ON SP.ResourceID = MARP.ResourceID
          AND RTRIM(LTRIM(UPPER(SP.ProductName))) 
                LIKE RTRIM(LTRIM(UPPER(MARP.DisplayName0)))
          AND RTRIM(LTRIM(UPPER(SP.ProductVersion))) 
                LIKE RTRIM(LTRIM(UPPER(MARP.Version0)))
LEFT JOIN v_GS_INSTALLED_SOFTWARE GSI
  ON SP.ResourceID = GSI.ResourceID
          AND RTRIM(LTRIM(UPPER(SP.ProductName))) 
                LIKE RTRIM(LTRIM(UPPER(GSI.ProductName0)))
          AND RTRIM(LTRIM(UPPER(SP.ProductVersion))) 
                LIKE RTRIM(LTRIM(UPPER(GSI.ProductVersion0)))

Where SYS.Netbios_Name0 Like 'CH-%' 
AND (MARP.InstallDate0 NOT LIKE ''
OR GSI.InstallDate0 NOT LIKE '')

ORDER By PCName, Vendor, Product, Version

​

​

Answer 1

结束整个查询，然后按主键进行分区，只过滤rownum=1

select * from (
select *, row_number() over(partition by PCName, Vendor, Product, Version order by PCName, Vendor, Product, Version) rownum from (
SELECT   
   SYS.Netbios_Name0 as PCName,
   ARP.Publisher0 as Vendor,
   ARP.DisplayName0 as Product,
   ARP.Version0 as Version,
   replace(replace(convert(varchar,ARP.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate,
   replace(replace(convert(varchar,ARP.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate2
FROM v_Add_Remove_Programs ARP
JOIN v_R_System SYS 
  ON ARP.ResourceID=SYS.ResourceID
WHERE SYS.Netbios_Name0 like 'CH-%' and InstallDate0 NOT LIKE ''

UNION

Select  
    SYS.Netbios_Name0 as PCName,
    SP.CompanyName as Vendor, 
    SP.ProductName as Product, 
    SP.ProductVersion as Version,
    replace(replace(convert(varchar,MARP.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate,
    replace(replace(convert(varchar,GSI.InstallDate0,120),'-',''),' 00:00:00','') as InstallDate2
FROM v_GS_SoftwareProduct SP
JOIN v_R_System SYS 
  ON SP.ResourceID=SYS.ResourceID

LEFT JOIN v_GS_Mapped_Add_Remove_Programs MARP
  ON SP.ResourceID = MARP.ResourceID
          AND RTRIM(LTRIM(UPPER(SP.ProductName))) 
                LIKE RTRIM(LTRIM(UPPER(MARP.DisplayName0)))
          AND RTRIM(LTRIM(UPPER(SP.ProductVersion))) 
                LIKE RTRIM(LTRIM(UPPER(MARP.Version0)))
LEFT JOIN v_GS_INSTALLED_SOFTWARE GSI
  ON SP.ResourceID = GSI.ResourceID
          AND RTRIM(LTRIM(UPPER(SP.ProductName))) 
                LIKE RTRIM(LTRIM(UPPER(GSI.ProductName0)))
          AND RTRIM(LTRIM(UPPER(SP.ProductVersion))) 
                LIKE RTRIM(LTRIM(UPPER(GSI.ProductVersion0)))

Where SYS.Netbios_Name0 Like 'CH-%' 
AND (MARP.InstallDate0 NOT LIKE ''
OR GSI.InstallDate0 NOT LIKE '')
)a)b
where rownum=1

Answer 2

暂时忘掉UNION，假设您在Table1中插入了UNION结果，然后只使用ROW_NUMBER()来选择您需要的字段组合的第一个幻影。

SELECT *
FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY PCName, Vendor, Product, Version
                                   ORDER BY InstallDate) as rn
      FROM Table1
     ) as T
WHERE rn = 1