Agfdhyk

In SQL Server Management Studio 2008 (R2) and newer, you can Right Click on the

DB -> Tasks -> Generate Scripts

• Select the tables you want to DROP.




• Select "Save to new query window".




• Click on the Advanced button.




• Set Script DROP and CREATE to Script DROP.




• Set Script Foreign Keys to True.




• Click OK.




• Click Next -> Next -> Finish.




• View the script and then Execute.

If you drop the "child" table first, the foreign key will be dropped as well. If you attempt to drop the "parent" table first, you will get an "Could not drop object 'a' because it is referenced by a FOREIGN KEY constraint." error.

Here is another way to drop all tables correctly, using sp_MSdropconstraints procedure. The shortest code I could think of:

exec sp_MSforeachtable "declare @name nvarchar(max); set @name = parsename('?', 1); exec sp_MSdropconstraints @name";

exec sp_MSforeachtable "drop table ?";

If it is SQL Server you must drop the constraint before you can drop the table.

Slightly more generic version of what @mark_s posted, this helped me

SELECT 

'ALTER TABLE ' +  OBJECT_SCHEMA_NAME(k.parent_object_id) +

'.[' + OBJECT_NAME(k.parent_object_id) + 

'] DROP CONSTRAINT ' + k.name

FROM sys.foreign_keys k

WHERE referenced_object_id = object_id('your table')

just plug your table name, and execute the result of it.

Here's another way to do delete all the constraints followed by the tables themselves, using a concatenation trick involving FOR XML PATH('') which allows merging multiple input rows into a single output row. Should work on anything SQL 2005 & later.

I've left the EXECUTE commands commented out for safety.

DECLARE @SQL NVARCHAR(max)

;WITH fkeys AS (

    SELECT quotename(s.name) + '.' + quotename(o.name) tablename, quotename(fk.name) constraintname 

    FROM sys.foreign_keys fk

    JOIN sys.objects o ON fk.parent_object_id = o.object_id

    JOIN sys.schemas s ON o.schema_id = s.schema_id

)

SELECT @SQL = STUFF((SELECT '; ALTER TABLE ' + tablename + ' DROP CONSTRAINT ' + constraintname

FROM fkeys

FOR XML PATH('')),1,2,'')



-- EXECUTE(@sql)



SELECT @SQL = STUFF((SELECT '; DROP TABLE ' + quotename(TABLE_SCHEMA) + '.' + quotename(TABLE_NAME) 

FROM INFORMATION_SCHEMA.TABLES 

FOR XML PATH('')),1,2,'')



-- EXECUTE(@sql)

Here is a complete script to implement a solution:

create Procedure [dev].DeleteTablesFromSchema

(

    @schemaName varchar(500)

)

As 

begin

    declare @constraintSchemaName nvarchar(128), @constraintTableName nvarchar(128),  @constraintName nvarchar(128)

    declare @sql nvarchar(max)

    -- delete FK first

    declare cur1 cursor for

    select distinct 

    CASE WHEN t2.[object_id] is NOT NULL  THEN  s2.name ELSE s.name END as SchemaName,

    CASE WHEN t2.[object_id] is NOT NULL  THEN  t2.name ELSE t.name END as TableName,

    CASE WHEN t2.[object_id] is NOT NULL  THEN  OBJECT_NAME(d2.constraint_object_id) ELSE OBJECT_NAME(d.constraint_object_id) END as ConstraintName

    from sys.objects t 

        inner join sys.schemas s 

            on t.[schema_id] = s.[schema_id]

        left join sys.foreign_key_columns d 

            on  d.parent_object_id = t.[object_id]

        left join sys.foreign_key_columns d2 

            on  d2.referenced_object_id = t.[object_id]

        inner join sys.objects t2 

            on  d2.parent_object_id = t2.[object_id]

        inner join sys.schemas s2 

            on  t2.[schema_id] = s2.[schema_id]

    WHERE t.[type]='U' 

        AND t2.[type]='U'

        AND t.is_ms_shipped = 0 

        AND t2.is_ms_shipped = 0 

        AND s.Name=@schemaName

    open cur1

    fetch next from cur1 into @constraintSchemaName, @constraintTableName, @constraintName

    while @@fetch_status = 0

    BEGIN

        set @sql ='ALTER TABLE ' + @constraintSchemaName + '.' + @constraintTableName+' DROP CONSTRAINT '+@constraintName+';'

        exec(@sql)

        fetch next from cur1 into @constraintSchemaName, @constraintTableName, @constraintName

    END

    close cur1

    deallocate cur1



    DECLARE @tableName nvarchar(128)

    declare cur2 cursor for

    select s.Name, p.Name

    from sys.objects p

        INNER JOIN sys.schemas s ON p.[schema_id] = s.[schema_id]

    WHERE p.[type]='U' and is_ms_shipped = 0 

    AND s.Name=@schemaName

    ORDER BY s.Name, p.Name

    open cur2



    fetch next from cur2 into @schemaName,@tableName

    while @@fetch_status = 0

    begin

        set @sql ='DROP TABLE ' + @schemaName + '.' + @tableName

        exec(@sql)

        fetch next from cur2 into @schemaName,@tableName

    end



    close cur2

    deallocate cur2



end

go

If I want to delete all the tables in
my database

Then it's a lot easier to drop the entire database:

DROP DATABASE WorkerPensions

Removing Referenced FOREIGN KEY Constraints

Assuming there is a parent and child table Relationship in SQL Server:



--First find the name of the Foreign Key Constraint:

  SELECT * 

  FROM sys.foreign_keys

  WHERE referenced_object_id = object_id('States')



--Then Find foreign keys referencing to dbo.Parent(States) table:

   SELECT name AS 'Foreign Key Constraint Name', 

           OBJECT_SCHEMA_NAME(parent_object_id) + '.' + OBJECT_NAME(parent_object_id) AS 'Child Table'

   FROM sys.foreign_keys 

   WHERE OBJECT_SCHEMA_NAME(referenced_object_id) = 'dbo' AND 

              OBJECT_NAME(referenced_object_id) = 'dbo.State'



 -- Drop the foreign key constraint by its name 

   ALTER TABLE dbo.cities DROP CONSTRAINT FK__cities__state__6442E2C9;



 -- You can also use the following T-SQL script to automatically find 

 --and drop all foreign key constraints referencing to the specified parent 

 -- table:



 BEGIN



DECLARE @stmt VARCHAR(300);



-- Cursor to generate ALTER TABLE DROP CONSTRAINT statements  

 DECLARE cur CURSOR FOR

 SELECT 'ALTER TABLE ' + OBJECT_SCHEMA_NAME(parent_object_id) + '.' + 

 OBJECT_NAME(parent_object_id) +

                ' DROP CONSTRAINT ' + name

 FROM sys.foreign_keys 

 WHERE OBJECT_SCHEMA_NAME(referenced_object_id) = 'dbo' AND 

            OBJECT_NAME(referenced_object_id) = 'states';



 OPEN cur;

 FETCH cur INTO @stmt;



 -- Drop each found foreign key constraint 

  WHILE @@FETCH_STATUS = 0

  BEGIN

    EXEC (@stmt);

    FETCH cur INTO @stmt;

  END



  CLOSE cur;

  DEALLOCATE cur;



  END

  GO



--Now you can drop the parent table:



 DROP TABLE states;

--# Command(s) completed successfully.

Using SQL Server Manager you can drop foreign key constraints from the UI. If you want to delete the table Diary but the User table has a foreign key DiaryId pointing to the Diary table, you can expand (using the plus symbol) the User table and then expand the Foreign Keys section. Right click on the foreign key that points to the diary table then select Delete. You can then expand the Columns section, right click and delete the column DiaryId too. Then you can just run:

drop table Diary

I know your actual question is about deleting all tables, so this may not be a useful for that case. However, if you just want to delete a few tables this is useful I believe (the title does not explicitly mention deleting all tables).

If you are on a mysql server and if you don't mind loosing your tables, you can use a simple query to delete multiple tables at once:

SET foreign_key_checks = 0;

DROP TABLE IF EXISTS table_a,table_b,table_c,table_etc;

SET foreign_key_checks = 1;

In this way it doesn't matter in what order you use the table in you query.

If anybody is going to say something about the fact that this is not a good solution if you have a database with many tables: I agree!