I want to drop the all foreign keys that have the following conditions.
SELECT CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE TABLE_NAME IN ('Table1', 'Table2')
AND CONSTRAINT_NAME LIKE '%FK__%__DL%'
There is a table named INFORMATION_SCHEMA.TABLE_CONSTRAINTS
which stores all tables constraints. constraint type of FOREIGN KEY
is also keeps in that table. So by filtering of this type you can reach to all foreign keys.
SELECT *
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'
If you create a dynamic query (for DROP
-ing the foreign key) in order to alter the table, you can reach to the aim of altering the constraints of all tables.
WHILE(EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_TYPE = 'FOREIGN KEY' AND TABLE_NAME IN ('Table1', 'Table2') AND CONSTRAINT_NAME LIKE '%FK__%__DL%'))
BEGIN
DECLARE @sql_alterTable_fk NVARCHAR(2000)
SELECT TOP 1 @sql_alterTable_fk = ('ALTER TABLE ' + TABLE_SCHEMA + '.[' + TABLE_NAME + '] DROP CONSTRAINT [' + CONSTRAINT_NAME + ']')
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'
AND TABLE_NAME IN ('Table1', 'Table2')
AND CONSTRAINT_NAME LIKE '%FK__%__DL%'
EXEC (@sql_alterTable_fk)
END
EXISTS
function with its parameter assures that there is at least one constrain for foreign key.
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