Because the object name was found ' dbo. T3 ' and index name ' pk__t3__3214ec2706cc942b ' have duplicate keys, so the CREATE UNIQUE index statement terminates. The duplicate key value is (1).

SQL statement: ALTER TABLE T3 ADD PRIMARY KEY (ID);

Execution Error:

MSG 1505, Level 16, State 1, line 1th
Because the object name was found ' dbo. T3 ' and index name ' pk__t3__3214ec270466e04c ' have duplicate keys, so the CREATE UNIQUE index statement terminates. The duplicate key value is (1).
Msg 1750, Level 16, State 0, line 1th
Unable to create constraint. See the preceding error message.
Statement has been terminated.

Cause of Error:

To build a primary key on the ID column, but the ID column data is duplicated and not unique.

Because the object name was found ' dbo. T3 ' and index name ' pk__t3__3214ec2706cc942b ' have duplicate keys, so the CREATE UNIQUE index statement terminates. The duplicate key value is (1).