Contents

• colnames 1.7.0
  • Synopsis
  • Description
  • Usage
  • Support
  • Authors
  • Copyright and License

colnames 1.7.0

Synopsis

try=# CREATE EXTENSION colnames;
CREATE EXTENSION

try=# SELECT colnames( ROW(1, 'foo', 458.0) );
  colnames
------------
 {f1,f2,f3}

try=# SELECT colnames( ROW(c.*)::pg_collation ) FROM pg_collation c LIMIT 1;
                                colnames
-----------------------------------------------------------------------
 {collname,collnamespace,collowner,collencoding,collcollate,collctype}

Description

This extension contains a single SQL function, colnames(), that takes a record value as its argument and returns an array of the names of the columns in that record. This can be useful for example in trigger functions, where one might need to get the column names in order to generate a query string.

Usage

Simply pass a record value to the function and it will return an array of the column names for that record:

try=# SELECT colnames( ROW(1, 'foo', 458.0) );
  colnames
------------
 {f1,f2,f3}

Note that this function is not strict; it’s legal to pass in a null record of a named composite type:

try=# SELECT colnames( NULL::pg_collation );
                                colnames
-----------------------------------------------------------------------
 {collname,collnamespace,collowner,collencoding,collcollate,collctype}

Warning: The indexes of the resulting array do not necessarily correspond to the values one might find when fetching column names from pg_attribute.attnum, since columns are not returned. The resulting array does correspond to the order of fields that would be returned by, say, SELECT (rec).*.

Support

This library is stored in a public GitHub repository. Feel free to fork and contribute! Please file bug reports via GitHub Issues.

Authors

• Andrew Gierth
• David E. Wheeler

Copyright and License

Copyright (c) 2011-2024 Andrew Gierth and David E. Wheeler.

This module is free software; you can redistribute it and/or modify it under the PostgreSQL License.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.

IN NO EVENT SHALL ANDREW GIERTH AND DAVID E. WHEELER BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF ANDREW GIERTH AND DAVID E. WHEELER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

ANDREW GIERTH AND DAVID E. WHEELER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN “AS IS” BASIS, AND ANDREW GIERTH AND DAVID E. WHEELER HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.