Sql-server – How to drop a foreign key in SQL Server

sql servertsql

I have created a foreign key (in SQL Server) by:

alter table company add CountryID varchar(3);
alter table company add constraint Company_CountryID_FK foreign key(CountryID) 
references Country;

I then run this query:

alter table company drop column CountryID;

and I get this error:

Msg 5074, Level 16, State 4, Line 2
The object 'Company_CountryID_FK' is dependent on column 'CountryID'.
Msg 4922, Level 16, State 9, Line 2
ALTER TABLE DROP COLUMN CountryID failed because one or more objects access this column

I have tried this, yet it does not seem to work:

alter table company drop foreign key Company_CountryID_FK; 
alter table company drop column CountryID;

What do I need to do to drop the CountryID column?

Thanks.

Best Answer

Try

alter table company drop constraint Company_CountryID_FK


alter table company drop column CountryID

Syntax:

ALTER TABLE {TABLENAME} 
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES

Example:

ALTER TABLE SomeTable
        ADD SomeCol Bit NULL --Or NOT NULL.
 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
    DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.

Notes:

Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6

Optional With-Values Statement:
The WITH VALUES is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES or not.

How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable and do not Specify SomeCol's value, then it will Default to 0.
If you insert a Record and Specify SomeCol's value as NULL (and your column allows nulls),
then the Default-Constraint will not be used and NULL will be inserted as the Value.

Notes were based on everyone's great feedback below.
Special Thanks to:
@Yatrix, @WalterStabosz, @YahooSerious, and @StackMan for their Comments.

Best Answer

Related Solutions

Sql – How to create a foreign key in SQL Server

Sql – Add a column with a default value to an existing table in SQL Server

Syntax:

Example:

Notes:

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