SQL Server: drop table cascade equivalent? - sql

Question

In oracle, to drop all tables and constraints you would type something like
DROP TABLE myTable CASCADE CONSTRAINTS PURGE;
and this would completely delete the tables and their dependencies. What's the SQL server equivalent??

Answer 1

In SQL Server Management Studio, go to Options / SQL Server Object Explorer / Scripting, and enable 'Generate script for dependent objects'. Then right click the table, script > drop to > new query window and it will generate it for you.

Answer 2

I don't believe SQL has a similarly elegant solution. You have to drop any related constraints first before you can drop the table.
Fortunately, this is all stored in the information schema and you can access that to get your whack list.
This blog post should be able to get you what you need:
http://weblogs.asp.net/jgalloway/archive/2006/04/12/442616.aspx
-- t-sql scriptlet to drop all constraints on a table
DECLARE #database nvarchar(50)
DECLARE #table nvarchar(50)
set #database = 'DatabaseName'
set #table = 'TableName'
DECLARE #sql nvarchar(255)
WHILE EXISTS(select * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where constraint_catalog = #database and table_name = #table)
BEGIN
select #sql = 'ALTER TABLE ' + #table + ' DROP CONSTRAINT ' + CONSTRAINT_NAME
from INFORMATION_SCHEMA.TABLE_CONSTRAINTS
where constraint_catalog = #database and
table_name = #table
exec sp_executesql #sql
END

Answer 3

This might be a horrible solution, but I find it's quick. It is similar to Vinnie's answer, but the product of the SQL statement is another series of SQL statements that will delete all constraints and tables.
(
select
'ALTER TABLE ' + tc.table_name + ' DROP CONSTRAINT ' + tc.constraint_name + ';'
from
INFORMATION_SCHEMA.TABLES t
,INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
where
t.table_name = tc.table_name
and tc.constraint_name not like '%_pk'
and tc.constraint_name not like 'pk_%'
and t.table_catalog='<schema>'
) UNION (
select
'DROP TABLE ' + t.table_name + ';'
from
INFORMATION_SCHEMA.TABLES t
where
t.table_catalog='<schema>'
)

Answer 4

This is all fun and games until some table references your table...
Then I must alter the code provided like so :
CREATE PROCEDURE _cascadeConstraints #database nvarchar(30) = NULL, #table nvarchar(60) = NULL
as
DECLARE #sql nvarchar(255)
WHILE EXISTS(select * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where constraint_catalog = #database and table_name = #table)
BEGIN
select #sql = 'ALTER TABLE ' + #table + ' DROP CONSTRAINT ' + CONSTRAINT_NAME
from INFORMATION_SCHEMA.TABLE_CONSTRAINTS
where constraint_catalog = #database and
table_name = #table
select #sql = 'ALTER TABLE ' + tc.TABLE_NAME + ' DROP CONSTRAINT ' + tc.CONSTRAINT_NAME
from INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc join
INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc on
(rc.CONSTRAINT_CATALOG = tc.CONSTRAINT_CATALOG and
rc.CONSTRAINT_NAME = tc.CONSTRAINT_NAME) join
INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc_pk on
(tc_pk.CONSTRAINT_CATALOG = rc.CONSTRAINT_CATALOG and
tc_pk.CONSTRAINT_NAME = rc.UNIQUE_CONSTRAINT_NAME)
where tc.constraint_catalog = #database
and tc_pk.TABLE_NAME = #table
exec sp_executesql #sql
END
go

Answer 5

Ultimately we are deleting our table.
So we can simply run 2 following command:
ALTER TABLE ... DROP CONSTRAINT ...
DROP TABLE ...
1> ALTER TABLE PRJ_DETAILS DROP CONSTRAINT FK_PRJ_TYPE;
-- Table name and Constraint Name are the parameter
2> DROP TABLE .
First drop constraint with its name associated with it table
Second you can drop table.
It worked for me and its easy also.

Answer 6

I just need delete the foreign key
DECLARE #database nvarchar(50)
DECLARE #TABLE_NAME nvarchar(250)
DECLARE #CONSTRAINT_NAME nvarchar(250)
DECLARE #sql nvarchar(350)
set #database = 'XXX'
DECLARE db_cursor CURSOR FOR
select TABLE_NAME, CONSTRAINT_NAME from INFORMATION_SCHEMA.TABLE_CONSTRAINTS where constraint_catalog = #database and CONSTRAINT_TYPE='FOREIGN KEY'
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #TABLE_NAME, #CONSTRAINT_NAME
WHILE ##FETCH_STATUS = 0
BEGIN
select #sql = 'ALTER TABLE ' + #TABLE_NAME + ' DROP CONSTRAINT ' + #CONSTRAINT_NAME
from INFORMATION_SCHEMA.TABLE_CONSTRAINTS
where constraint_catalog = #database and
table_name = #TABLE_NAME
exec sp_executesql #sql
FETCH NEXT FROM db_cursor INTO #TABLE_NAME, #CONSTRAINT_NAME
END
CLOSE db_cursor
DEALLOCATE db_cursor