In this case, you just have to execute the first DELETE statement only to delete rows in two tables.. Is it feasible to have another version of your code that traverses the schema hierarchy in reverse of a DELETE in order to perform inserts? However, it looks as if Pname in tables tbl1, tbl2, tbl3 and tbl5 are foreign keys to Pname on tbl4. Re-enable the Constraints the information of how deep (i.e. A foreign key value may be NULL and indicates a particular record has no parent record. You can get SQL to do much of the work for you by using Cascade Delete[] And don't forget the MSDN documentation Create Foreign Key Relationships | Microsoft Docs[] This ensures the integrity of the data. Before You Begin Security Permissions. Using Relational Database - Create a relation between a table having Primary Key and a table having Foreign Key with Delete constrain. There are generally two scenarios when deleting data from tables with FKs, one is to delete For example, each employee is working in one or more territories and each territory has multiple employees. Because the vast majority of  [Transactions] have to be preserved, a sliding window partition switch is the fastest method I tested. out the following: Great article. Instead, set up a foreign key relationship between tables that includes an ON DELETE CASCADE or ON UPDATE CASCADE constraint. Programatically - First delete a record from a table with Primary Key and using the ID of this record, delete the records in a table with Foreign Key having the respective ID. To perform multiple-table deletes or updates for InnoDB tables, you need not use the syntax just described. referenced table) and who is a child table (i.e. Foreign key constraints are an integral part of SQL Server database design. That would have taken a very long time to code by hand. Any help is appreciated, We may have complex and long foreign key relationships, Foreign keys may be composed of multiple columns. SELECT * FROM [Contact.Data] WHERE BID = @BID AND ID = @ID, SELECT * FROM [Order.Data] WHERE BID = @BID AND CompanyID = @ID, EXEC [Util.Table.CascadeDelete] @TableName = 'dbo. The script you provided is still very useful as the manual amendments are minimal compared to writing the scriptfrom scratch. Some names and products listed are the registered trademarks of their respective owners. A FOREIGN KEY is a key used to link two tables together. Open a new SSMS window, and run the following code. In all these scenarios, we cannot tell who is a parent table (i.e. CREATE TABLE parent ( id INT NOT NULL, PRIMARY KEY (id) ); CREATE TABLE child ( id INT, parent_id INT, FOREIGN KEY (parent_id) REFERENCES parent(id) ON DELETE CASCADE ); You can read more about ON DELETE CASCADE here. That means my systems can't tolerate long-running transactions, where "long" is measured in tens of milliseconds. To drop a UNIQUE constraint, use the following SQL: SQL Server / Oracle / MS Access: ALTER TABLE Persons DROP CONSTRAINT UC_Person; MySQL: ALTER TABLE Persons DROP INDEX UC_Person; DROP a PRIMARY KEY Constraint. I think there is a small problem when a table with FKs has two different columns pointing to the same parent table and I'm not sure how to fix it. I was able to change the script so it would use alias names in the cases where a table is listed multiple times. Be very careful with this, as it deletes. You can use oncascase delete over the primary-foreign key constraint, also you can run delete query on the table and then run DBCC CheckIdent() over the table… Specify foreign key for the details tables which references to the primary key of master and set Delete rule = Cascade . There are many good foreign key related table manipulation tips, please check Everything was working fine but after a few days, I am getting below error. Of course, for both scenarios we need to delete from the tables in the right order. IMO, using DELETEs in a loop should be the option of last resort. This self-referencing concept can be extended to multiple tables, like table A referring to table B and table B referring to table C and table C referring back to table A. Andrew A. Whirlpool Forums Addict reference: whrl.pl/RWfoe. I took and developed two SPROCs based on the above. 2. WHERE clause combined with complex joins and/or subqueries. To delete multiple rows in a table, you use the condition in the WHERE clause to identify the rows that should be deleted. What I tried to do in sql server management studio is set the ClassID in Classes as a primary key, then set foreign keys to the other three tables. The SPROC [Util.Table.CascadeDelete] implements the cascade deletion, and gives options to wrap it in a transaction, just return the SQL, or execute the SQL. My heaviest systems (typically an 8-way) are currently handling up to ~2000 batches/sec. [',object_name(parent_object_id),']'), WHERE referenced_object_id = object_id(@TableName). [Util.Table.DependencyList] @[email protected], @debug=0; DECLARE @where VARCHAR(MAX) = CONCAT('  WHERE ', @TableName, '.BID = @BID AND ', @TableName, '.ID = @ID '), 'DECLARE @BID SMALLINT =' , @BID, ';', @crlf, , 'DECLARE @ID INT =' , @ID, ';', @crlf, @crlf. ... id, primary key column1, tb_bid, #foreign key ref to TABLE B id TableD: id, name TableE id, name I tried JOIN but unfortunately its not working in SQLite. Let's say we have a SQL Server table named Table1 and it If you cannot change it, can you please make some suggestions? You can specify multiple tables in a DELETE statement to delete rows from one or more tables depending on the particular condition in the WHERE clause. rows with a The other record, with the forreign key: Do you want to keep that record - or should it be deleted too? Caveat Emptor. User #3103 3176 posts. This ensures the integrity of the data. While creating the table we haven't added ON DELETE CASCADE. The stored procedure I created was DELETE FROM Classes WHERE [email protected] I work with ~100 .Net developers, and  I am the sole DBA (albeit our load tester knows SQL Server well enough :). [Company.Data]', @BID = @BID, @ID = @ID, @ReturnSQL = 1, @ExecuteSQL = 0, @ReturnAffectedTables = 1, CREATE OR ALTER PROCEDURE dbo.[Util.Table.CascadeDelete]. Imagine if we had 5 or 6 tables with foreign keys into this parent table. Foreign Key is a column that refers to the primary key/unique key of other table. In this article, we explored a few examples on DELETE CASCADE and UPDATE CASCADE rules in SQL Server foreign key. You could also avoid the headache if your model supports cascading referential integrity constraints. If it is just one table, you can use SQL Server Management Studio (SSMS) or any other tool to visually check dependencies and correct your script. I typically need to dynamically generate a TOP (N) statement (and get the total number of rows in the tables being deleted): CREATE PROCEDURE [GetTop] (  @DatabaseName sysname,   @SchemaName sysname,   @TableName sysname,   @TopRowCount int OUTPUT,  @TableRows int OUTPUT )ASSET NOCOUNT ONCREATE TABLE [#Statistics] ([Density] smallint, [Rows] int), DECLARE  @SQL nvarchar(max),  @Density smallint, SET @SQL = N'USE ' + QUOTENAME(@DatabaseName) + ' INSERT [#Statistics]  SELECT   CAST(ROUND(SUM     (     CASE WHEN (p.index_id IN(0,1) AND au.type = 1)      THEN p.rows+1      ELSE 0      END) * 1.0      /     (CASE       WHEN (SUM(au.total_pages)=0)      THEN 1      ELSE SUM(au.total_pages)      END     ),0) AS int),  CAST(SUM    (    CASE WHEN (p.index_id IN(0,1) AND au.type = 1)     THEN p.rows+1     ELSE 1     END    ) AS int)  FROM [sys]. Employee is working in one table that refers to the SQL standard, etc need not the... List, same as above code to SHOW the FK tree a CHECK.. 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