DELETE (Transact- SQL) | Microsoft Docs. THIS TOPIC APPLIES TO: SQL Server (starting with 2. Azure SQL Database. Azure SQL Data Warehouse Parallel Data Warehouse Removes one or more rows from a table or view in SQL Server. Transact- SQL Syntax Conventions. Syntax- - Syntax for SQL Server and Azure SQL Database. Similar languages. PL/SQL works analogously to the embedded procedural languages associated with other relational databases. For example, Sybase ASE and Microsoft SQL. Sql server interview questions and answers for freshers and experienced, SQL Server interview questions pdf, SQL Server online test, SQL server Jobs. WITH < common_table_expression> [ .. TOP ( expression ) [ PERCENT ] ]. FROM ]. { { table_alias. WITH ( table_hint_limited [ .. OUTPUT Clause> ]. FROM table_source [ .. WHERE { < search_condition>. CURRENT OF. { { [ GLOBAL ] cursor_name }. OPTION ( < Query Hint> [ .. Syntax for Azure SQL Data Warehouse and Parallel Data Warehouse. DELETE FROM [database_name . WHERE < search_condition> ]. OPTION ( < query_options> [ .. ![]() Removes one or more rows from a table or view in SQL Server. Specifies the temporary named result set, also known as common table expression, defined within the scope. SQLCODES for SQL DB2 in MVS, OS390, ZOS Tutorial. Arguments WITH < common_table_expression> Specifies the temporary named result set, also known as common table expression, defined within the scope of the DELETE statement. The result set is derived from a SELECT statement. Common table expressions can also be used with the SELECT, INSERT, UPDATE, and CREATE VIEW statements. For more information, see WITH common_table_expression (Transact- SQL). TOP (expression) [ PERCENT ]Specifies the number or percent of random rows that will be deleted. The rows referenced in the TOP expression used with INSERT, UPDATE, or DELETE are not arranged in any order. For more information, see TOP (Transact- SQL). FROMAn optional keyword that can be used between the DELETE keyword and the target table_or_view_name, or rowset_function_limited. The alias specified in the FROM table_source clause representing the table or view from which the rows are to be deleted. Applies to: SQL Server 2. SQL Server 2. 01. The name of the server (using a linked server name or the OPENDATASOURCE function as the server name) on which the table or view is located. If server_name is specified, database_name and schema_name are required. The name of the database. The name of the schema to which the table or view belongs. The name of the table or view from which the rows are to be removed. A table variable, within its scope, also can be used as a table source in a DELETE statement. The view referenced by table_or_view_name must be updatable and reference exactly one base table in the FROM clause of the view definition. For more information about updatable views, see CREATE VIEW (Transact- SQL). Applies to: SQL Server 2. SQL Server 2. 01. Either the OPENQUERY or OPENROWSET function, subject to provider capabilities. WITH ( < table_hint_limited> [.. Specifies one or more table hints that are allowed for a target table. The WITH keyword and the parentheses are required. NOLOCK and READUNCOMMITTED are not allowed. For more information about table hints, see Table Hints (Transact- SQL). OUTPUT_Clause> Returns deleted rows, or expressions based on them, as part of the DELETE operation. The OUTPUT clause is not supported in any DML statements targeting views or remote tables. For more information, see OUTPUT Clause (Transact- SQL). FROM table_source. Specifies an additional FROM clause. This Transact- SQL extension to DELETE allows specifying data from < table_source> and deleting the corresponding rows from the table in the first FROM clause. This extension, specifying a join, can be used instead of a subquery in the WHERE clause to identify rows to be removed. For more information, see FROM (Transact- SQL). WHERESpecifies the conditions used to limit the number of rows that are deleted. If a WHERE clause is not supplied, DELETE removes all the rows from the table. There are two forms of delete operations based on what is specified in the WHERE clause: Searched deletes specify a search condition to qualify the rows to delete. For example, WHERE column_name = value. Positioned deletes use the CURRENT OF clause to specify a cursor. The delete operation occurs at the current position of the cursor. This can be more accurate than a searched DELETE statement that uses a WHERE search_condition clause to qualify the rows to be deleted. A searched DELETE statement deletes multiple rows if the search condition does not uniquely identify a single row. Specifies the restricting conditions for the rows to be deleted. There is no limit to the number of predicates that can be included in a search condition. For more information, see Search Condition (Transact- SQL). CURRENT OFSpecifies that the DELETE is performed at the current position of the specified cursor. GLOBALSpecifies that cursor_name refers to a global cursor. Is the name of the open cursor from which the fetch is made. If both a global and a local cursor with the name cursor_name exist, this argument refers to the global cursor if GLOBAL is specified; otherwise, it refers to the local cursor. The cursor must allow updates. The name of a cursor variable. The cursor variable must reference a cursor that allows updates. OPTION ( < query_hint> [ .. Keywords that indicate which optimizer hints are used to customize the way the Database Engine processes the statement. For more information, see Query Hints (Transact- SQL). Best Practices To delete all the rows in a table, use TRUNCATE TABLE. TRUNCATE TABLE is faster than DELETE and uses fewer system and transaction log resources. TRUNCATE TABLE has restrictions, for example, the table cannot participate in replication. For more information, see TRUNCATE TABLE (Transact- SQL) Use the @@ROWCOUNT function to return the number of deleted rows to the client application. For more information, see @@ROWCOUNT (Transact- SQL). Error Handling You can implement error handling for the DELETE statement by specifying the statement in a TRY…CATCH construct. The DELETE statement may fail if it violates a trigger or tries to remove a row referenced by data in another table with a FOREIGN KEY constraint. If the DELETE removes multiple rows, and any one of the removed rows violates a trigger or constraint, the statement is canceled, an error is returned, and no rows are removed. When a DELETE statement encounters an arithmetic error (overflow, divide by zero, or a domain error) occurring during expression evaluation, the Database Engine handles these errors as if SET ARITHABORT is set ON. The rest of the batch is canceled, and an error message is returned. Interoperability DELETE can be used in the body of a user- defined function if the object modified is a table variable. When you delete a row that contains a FILESTREAM column, you also delete its underlying file system files. The underlying files are removed by the FILESTREAM garbage collector. For more information, see Access FILESTREAM Data with Transact- SQL. The FROM clause cannot be specified in a DELETE statement that references, either directly or indirectly, a view with an INSTEAD OF trigger defined on it. For more information about INSTEAD OF triggers, see CREATE TRIGGER (Transact- SQL). Limitations and Restrictions When TOP is used with DELETE, the referenced rows are not arranged in any order and the ORDER BY clause can not be directly specified in this statement. If you need to use TOP to delete rows in a meaningful chronological order, you must use TOP together with an ORDER BY clause in a subselect statement. See the Examples section that follows in this topic. TOP cannot be used in a DELETE statement against partitioned views. Locking Behavior By default, a DELETE statement always acquires an exclusive (X) lock on the table it modifies, and holds that lock until the transaction completes. With an exclusive (X) lock, no other transactions can modify data; read operations can take place only with the use of the NOLOCK hint or read uncommitted isolation level. You can specify table hints to override this default behavior for the duration of the DELETE statement by specifying another locking method, however, we recommend that hints be used only as a last resort by experienced developers and database administrators. For more information, see Table Hints (Transact- SQL). When rows are deleted from a heap the Database Engine may use row or page locking for the operation. As a result, the pages made empty by the delete operation remain allocated to the heap. When empty pages are not deallocated, the associated space cannot be reused by other objects in the database. To delete rows in a heap and deallocate pages, use one of the following methods. Specify the TABLOCK hint in the DELETE statement. Using the TABLOCK hint causes the delete operation to take an exclusive lock on the table instead of a row or page lock. SQL Server / T- SQL examples (example source code) Organized by topicjava. Email: info at java. Demo Source and Support. All rights reserved.
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