SQL Server – Drop a Foreign Key Constraint That Is Not a Foreign Key

foreign-keyssql-server-2008

I am using SQL Server 2008 and its Management Studio. I am doing a web project, which has a tool to automate the tables/relationships creation.

My web project reveals this error:

Unsuccessful: alter table Tester add constraint FK_c6c4bf4s2rvp56a32nnruww2b foreign key (game) references Game

Column 'Game.id' is not the same data type as referencing column 'Tester.game' in foreign key 'FK_c6c4bf4s2rvp56a32nnruww2b'

However, when I ran the following in the management studio:

ALTER TABLE dbo.Tester DROP CONSTRAINT FK_c6c4bf4s2rvp56a32nnruww2b

I get the following:

Msg 3728, Level 16, State 1, Line 1
'FK_c6c4bf4s2rvp56a32nnruww2b' is not a constraint.
Msg 3727, Level 16, State 0, Line 1
Could not drop constraint. See previous errors.

I am confused. What type of constraint is FK_c6c4bf4s2rvp56a32nnruww2b?

How can I remove it?

Thanks and regards.

Best Answer

You can try

 sp_help [table_name]

to get all the foreign key constraints.

When you get the foreign key constraints on the table. Drop them by writing something like this:-

ALTER TABLE [dbo].[table_name] DROP CONSTRAINT [Foreign_FK]

Related Solutions

SQL Server – How to Drop a Foreign Key

Try

alter table company drop constraint Company_CountryID_FK


alter table company drop column CountryID

SQL Server – How to Drop a Foreign Key Constraint Only If It Exists

This is a lot simpler than the current proposed solution:

IF (OBJECT_ID('dbo.FK_ConstraintName', 'F') IS NOT NULL)
BEGIN
    ALTER TABLE dbo.TableName DROP CONSTRAINT FK_ConstraintName
END

If you need to drop another type of constraint, these are the applicable codes to pass into the OBJECT_ID() function in the second parameter position:

C = CHECK constraint
D = DEFAULT (constraint or stand-alone)
F = FOREIGN KEY constraint
PK = PRIMARY KEY constraint
UQ = UNIQUE constraint

You can also use OBJECT_ID without the second parameter.

Full List of types here:

Object type:

AF = Aggregate function (CLR)
C = CHECK constraint
D = DEFAULT (constraint or stand-alone)
F = FOREIGN KEY constraint
FN = SQL scalar function
FS = Assembly (CLR) scalar-function
FT = Assembly (CLR) table-valued function
IF = SQL inline table-valued function
IT = Internal table
P = SQL Stored Procedure
PC = Assembly (CLR) stored-procedure
PG = Plan guide
PK = PRIMARY KEY constraint
R = Rule (old-style, stand-alone)
RF = Replication-filter-procedure
S = System base table
SN = Synonym
SO = Sequence object

Applies to: SQL Server 2012 through SQL Server 2014.

SQ = Service queue
TA = Assembly (CLR) DML trigger
TF = SQL table-valued-function
TR = SQL DML trigger
TT = Table type
U = Table (user-defined)
UQ = UNIQUE constraint
V = View
X = Extended stored procedure

Best Answer

Related Solutions

SQL Server – How to Drop a Foreign Key

SQL Server – How to Drop a Foreign Key Constraint Only If It Exists

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