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Last active August 29, 2015 13:57
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MSSQL 2008 allowing nulls in unique constraints.
Raw
gistfile1.sql
-- See http://technet.microsoft.com/en-us/library/ms188783.aspx
-- "For UNIQUE indexes, only the selected rows must have unique index values."
CREATE TABLE foo (pk int PRIMARY KEY IDENTITY, x int NULL);
GO
CREATE UNIQUE INDEX U_Foo_x ON foo (x) WHERE x is not null;
GO
INSERT INTO foo (x) VALUES (1);
INSERT INTO foo (x) VALUES (2);
INSERT INTO foo (x) VALUES (NULL);
INSERT INTO foo (x) VALUES (NULL);
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