I am working with SQL Server 2012 and I have one table that has 3 constraint primary key. I just want table structure like that =>
Combination of this 3 column must be unique
ColumnA ColumnB ColumnC
1 2 3
1 2 4
But when I test this table, This table can accept duplicate data like that=>
ColumnA ColumnB ColumnC
1 2 3
1 2 3
Why can I add duplicate value like that even constraint primary key? or Am I misunderstanding about constraint primary?