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USE tempdb
GO
IF OBJECT_ID('a') IS NOT NULL DROP TABLE a
IF OBJECT_ID('b') IS NOT NULL DROP TABLE b
IF OBJECT_ID('c') IS NOT NULL DROP TABLE c
GO
CREATE TABLE a(id INT,id1 INT,id2 INT,[name] NVARCHAR(20))
CREATE TABLE b(id INT,fid INT,name1 NVARCHAR(20))
CREATE TABLE c(id INT,fid INT,name2 NVARCHAR(20))
SELECT a.id,a.name FROM a INNER JOIN b ON a.id=b.fid
UNION
SELECT a.id,a.name FROM a INNER JOIN c ON a.id2=c.fid
a.id2 为空就没记录, 无所谓的了