Generates numbers starting at 1 for each successive row in the results of the query. The NUMBER function is primarily intended for use in select lists.
Due to limitations imposed by the NUMBER function (described in the Remarks section below), use the ROW_NUMBER function [Miscellaneous], instead. The ROW_NUMBER function provides the same functionality, but without the limitations of the NUMBER function.
NUMBER( * )
You can use NUMBER(*) in a select list to provide a sequential numbering of the rows in the result set. NUMBER(*) returns the value of the ANSI row number of each result row. This means that the NUMBER function can return positive or negative values, depending on how the application scrolls through the result set. For insensitive cursors, the value of NUMBER(*) will always be positive because the entire result set is materialized at OPEN.
In addition, the row number may be subject to change for some cursor types. The value is fixed for insensitive cursors and scroll cursors. If there are concurrent updates, it may change for dynamic and sensitive cursors.
A syntax error is generated if you use the NUMBER function in: a DELETE statement, a WHERE clause, a HAVING clause, an ORDER BY clause, a subquery, a query involving aggregation, any constraint, a GROUP BY clause, a DISTINCT clause, a query expression (UNION, EXCEPT, INTERSECT), or a derived table.
NUMBER(*) can be used in a view (subject to the above restrictions), but the view column corresponding to the expression involving NUMBER(*) can be referenced at most once in the query or outer view, and the view cannot participate as a NULL-supplying table in a left outer join or full outer join.
In embedded SQL, care should be exercised when using a cursor that references a query containing a NUMBER(*) function. In particular, this function returns negative numbers when a database cursor is positioned using relative to the end of the cursor (an absolute position with a negative offset).
You can use NUMBER in the right hand side of an assignment in the SET clause of an UPDATE statement. For example, SET x = NUMBER(*)
.
The NUMBER function can also be used to generate primary keys when using the INSERT from SELECT statement (see INSERT statement), although using an AUTOINCREMENT clause is a preferred mechanism for generating sequential primary keys.
For information about the AUTOINCREMENT clause, see CREATE TABLE statement.
SQL/2003 Vendor extension.
The following statement returns a sequentially-numbered list of departments.
SELECT NUMBER( * ), DepartmentName FROM Departments WHERE DepartmentID > 5 ORDER BY DepartmentName; |
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