Question

我有3张桌子。一个表格中包含所有人[Pat]，每个人都有一个唯一的[PatId]。第二个表包含保险公司的所有信息[Ins]，每个信息都有唯一的[InsId]。第三个表格包含患者保险信息[PatIns]。在[PatIns]表中，一些患者（也[PatId]）有第二或第三保险，并在[InsType]中表示为1,2或3.我需要一个SQL查询，不仅加入3个表，但当患者有第二或第三保险时也返回数据。到目前为止，我有：

SELECT * 

FROM [XEREX_TEST].[dbo].[xrxPat], 

[XEREX_TEST].[dbo].[xrxIns],

[XEREX_TEST].[dbo].[xrxPatIns]

[XEREX_TEST].[dbo].[xrxPatIns] AS INS2,

[XEREX_TEST].[dbo].[xrxPatIns] AS INS3 

WHERE [xrxPat].[PatId]=[xrxPatIns].[PatId] 

AND [xrxPatIns].[PatId] = INS2.[PatId] 

AND [xrxPatIns].[PatId] = INS3.[PatId]

AND [xrxIns].[RecNo]=[xrxPatIns].[InsId] 

AND [xrxPatIns].[InsType]=1

AND INS2.[InsType]=2 

AND INS3.[InsType]=3;

问题是这只能让患者获得3种保险。如果患者只有1个保险，我想返回表INS2和/或INS3的所有患者和空值。知道怎么做吗？

Answer 1

虽然这可以在where子句中完成，但最好更改为使用显式连接，因为这样可以使代码更易于阅读。

SELECT
  *
FROM [XEREX_TEST].[dbo].[xrxPat]
INNER JOIN [XEREX_TEST].[dbo].[xrxIns]
    ON [xrxPat].[PatId] = [xrxIns].[PatId]
INNER JOIN [XEREX_TEST].[dbo].[xrxPatIns]
    ON [xrxIns].[RecNo] = [xrxPatIns].[InsId]
    AND [xrxPatIns].[InsType] = 1
LEFT JOIN [XEREX_TEST].[dbo].[xrxPatIns] AS INS2
    ON [xrxIns].[RecNo] = INS2.[PatId]
    AND INS2.[InsType] = 2
LEFT JOIN [XEREX_TEST].[dbo].[xrxPatIns] AS INS3
    ON [xrxIns].[RecNo] = INS3.[PatId]
    AND INS3.[InsType] = 3;

Answer 2

使用JOIN表示法而不是逗号。然后让他们LEFT JOIN。

SELECT * 
FROM 
(SELECT * FROM [XEREX_TEST].[dbo].[xrxPatIns] WHERE [InsType]=1) AS INS1
LEFT JOIN
(SELECT * FROM [XEREX_TEST].[dbo].[xrxPatIns] WHERE [InsType]=2) AS INS2
ON INS1.[PatId] = INS2.[PatId]
LEFT JOIN
(SELECT * FROM [XEREX_TEST].[dbo].[xrxPatIns] WHERE [InsType]=3) AS INS3
ON INS1.[PatId] = INS3.[PatId]
JOIN
[XEREX_TEST].[dbo].[xrxPat]
ON [xrxPat].[PatId]=INS1.[PatId] 
JOIN
[XEREX_TEST].[dbo].[xrxIns]
ON [xrxIns].[RecNo]=INS1.[InsId] 
;

SQL查询源代码

2 个答案: