Difference between revisions of "PSEUDO COLUMNS"
From Lianjapedia
Yvonne.milne (Talk | contribs) |
Helen.george (Talk | contribs) |
||
| Line 8: | Line 8: | ||
A Pseudo Column behaves like a table column, but is not actually stored in the table. You can select from Pseudo Columns, but they cannot be updated. They provide extra information about a row set. | A Pseudo Column behaves like a table column, but is not actually stored in the table. You can select from Pseudo Columns, but they cannot be updated. They provide extra information about a row set. | ||
| − | {| class="wikitable" width=100% | + | {| class="wikitable" width="100%" |
| − | !width=15%|Pseudo Columns||Description | + | !width="15%"|Pseudo Columns||Description |
|- | |- | ||
| − | |valign=top|[[CURRVAL]]||The CURRVAL Pseudo Column will return the current sequence number from the specified table. Sequence numbers can be used for primary and unique index keys. | + | |valign="top"|[[CURRVAL]]||The CURRVAL Pseudo Column will return the current sequence number from the specified table. Sequence numbers can be used for primary and unique index keys. |
|- | |- | ||
| − | |valign=top|[[NEXTVAL]]||The NEXTVAL Pseudo Column will return the next unique sequence number from the specified table. Sequence numbers can be used for primary and unique index keys. | + | |valign="top"|[[NEXTVAL]]||The NEXTVAL Pseudo Column will return the next unique sequence number from the specified table. Sequence numbers can be used for primary and unique index keys. |
|- | |- | ||
| − | |valign=top|[[ROWID]]||The ROWID Pseudo Column will return a number identifying the row’s physical stored position in the table. The ROWID Pseudo Column can be used to perform singleton selects, or optimize updates of a known ROWID. | + | |valign="top"|[[ROWID]]||The ROWID Pseudo Column will return a number identifying the row’s physical stored position in the table. The ROWID Pseudo Column can be used to perform singleton selects, or optimize updates of a known ROWID. |
|- | |- | ||
| − | |valign=top|[[SQLCNT]]||The SQLCNT Pseudo Column will return the number of rows affected by the last SQL statement. For example, after a SELECT statement, SQLCNT will contain the number of rows selected. | + | |valign="top"|[[SQLCNT]]||The SQLCNT Pseudo Column will return the number of rows affected by the last SQL statement. For example, after a SELECT statement, SQLCNT will contain the number of rows selected. |
|- | |- | ||
| − | |valign=top|[[SQLCODE]]||The SQLCODE Pseudo Column will return a number indicating the result of the last SQL statement. | + | |valign="top"|[[SQLCODE]]||The SQLCODE Pseudo Column will return a number indicating the result of the last SQL statement. |
|- | |- | ||
|} | |} | ||
Latest revision as of 09:04, 5 February 2013
Purpose
Provide extra information about a SELECT row set
See Also
Description
A Pseudo Column behaves like a table column, but is not actually stored in the table. You can select from Pseudo Columns, but they cannot be updated. They provide extra information about a row set.
| Pseudo Columns | Description |
|---|---|
| CURRVAL | The CURRVAL Pseudo Column will return the current sequence number from the specified table. Sequence numbers can be used for primary and unique index keys. |
| NEXTVAL | The NEXTVAL Pseudo Column will return the next unique sequence number from the specified table. Sequence numbers can be used for primary and unique index keys. |
| ROWID | The ROWID Pseudo Column will return a number identifying the row’s physical stored position in the table. The ROWID Pseudo Column can be used to perform singleton selects, or optimize updates of a known ROWID. |
| SQLCNT | The SQLCNT Pseudo Column will return the number of rows affected by the last SQL statement. For example, after a SELECT statement, SQLCNT will contain the number of rows selected. |
| SQLCODE | The SQLCODE Pseudo Column will return a number indicating the result of the last SQL statement. |
