hi.I wrote these commands and There is a problem.
-----tablo1 a1 column name=PK1 a Primary add constraint
Use test
GO
ALTER TABLE tablo1 ADD CONSTRAINT PK1 PRIMARY KEY (a1)
GO
error messages:
Msg 8111, Level 16, State 1, Line 1
Cannot define PRIMARY KEY constraint on nullable column in table 'tablo1'.
Msg 1750, Level 16, State 0, Line 1
Could not create constraint. See previous errors.