ASA SQL Reference
  SQL Statements

DELETE statement

Description 

Use this statement to delete rows from the database.

Syntax 

DELETE [ FIRST | TOP n ]
[ FROM ] [ owner.]table-name
[ FROM table-list ]
[ WHERE search-condition ]

Usage 

The DELETE statement deletes all the rows from the named table that satisfy the search condition. If no WHERE clause is specified, all rows from the named table are deleted.

The DELETE statement can be used on views, provided the SELECT statement defining the view has only one table in the FROM clause and does not contain a GROUP BY clause, an aggregate function, or involve a UNION operation.

The optional second FROM clause in the DELETE statement allows rows to be deleted based on joins. If the second FROM clause is present, the WHERE clause qualifies the rows of this second FROM clause. Rows are deleted from the table name given in the first FROM clause.

The second FROM clause can contain arbitrary complex table expressions, such as KEY and NATURAL joins. For a full description of the FROM clause and joins, see FROM clause.

The following statement illustrates a potential ambiguity in table names in DELETE statements with two FROM clauses that use correlation names:

DELETE
FROM table_1
FROM table_1 AS alias_1, table_2 AS alias_2
WHERE ...

The table table_1 is identified without a correlation name in the first FROM clause, but with a correlation name in the second FROM clause. In this case, table_1 in the first clause is identified with alias_1 in the second clause—there is only one instance of table_1 in this statement.

This is an exception to the general rule that where a table is identified with a correlation name and without a correlation name in the same statement, two instances of the table are considered.

Consider the following example:

DELETE
FROM table_1
FROM table_1 AS alias_1, table_1 AS alias_2
WHERE ...

In this case, there are two instances of table_1in the second FROM clause. The statement will fail with a syntax error as it is ambiguous which instance of the table_1 from the second FROM clause matches the first instance of table_1 in the first FROM clause.

Deleting a significant amount of data using the DELETE statement will also update column statistics.

Permissions 

Must have DELETE permission on the table.

Side effects 

None.

See also 

TRUNCATE TABLE statement

INSERT statement

INPUT statement [Interactive SQL]

FROM clause

Standards and compatibility 

• SQL/92    Entry-level compliant. The use of more than one table in the FROM clause is a vendor extension.

• SQL/99    Core feature. The use of more than one table in the FROM clause is a vendor extension.

• Sybase    Supported by Adaptive Server Enterprise, including the vendor extension.

Example 

Remove employee 105 from the database.

DELETE
FROM employee
WHERE emp_id = 105

Remove all data prior to 2000 from the fin_data table.

DELETE
FROM fin_data
WHERE year < 2000

Remove all orders from sales_order_items table if their ship date is older than 2001-01-01 and their region is Central.

DELETE
FROM sales_order_items
FROM sales_order
WHERE sales_order_items.id = sales_order.id
  and ship_date < '2001-01-01' and region ='Central'