To clear test data from a database we could use truncate commands but sometimes we need to get rid of foreign keys.

we could get constaint list from INFORMATION_SCHEMA.TABLE_CONSTRAINTS table.

for example :

we could remove foreign key by using this table and the following query.

while(exists(select 1 from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where CONSTRAINT_TYPE='FOREIGN KEY'))

begin
declare @sql nvarchar(2000)
SELECT TOP 1 @sql=('ALTER TABLE ' + TABLE_SCHEMA + '.[' + TABLE_NAME
+ '] DROP CONSTRAINT [' + CONSTRAINT_NAME + ']')
FROM information_schema.table_constraints
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'
exec (@sql)
end