---
name: "PQregisterSubClasses"
section: "3"
platform: "linux"
package: "libpqtypes-dev"
version: "1.5.1-9"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/PQregisterSubClasses"
---

# PQregisterSubClasses(3)

Registers a type aliases or sub-classes.

## NAME

PQregisterSubClasses - Registers a type aliases or sub-classes.

## SYNOPSIS

**#include \<libpqtypes.h\>**\

**int PQregisterSubClasses(PGconn \****conn***, PGregisterType \****types***,**\
\
                           **int** *count***);**

## DEPRECATED

*THIS FUNCTION IS DEPRECATED.  New applications should use PQregisterTypes.* *This function is now a wrapper to PQregisterTypes.*

## DESCRIPTION

*The PQregisterSubClasses() function allows an application* *to register an alias or sub-class of another type.*

*The types argument is an array containing count sub class types* *to register.  The typname member of the PGregisterType structure must* *specify an inheritence relationship: ex. "myint=int4" where myint inherits* *from int4.  The ´=´ is called the inheritence operator.  If both typput* *and typget members of the PGregisterType structure are NULL, the type at* *that element will behave identically to the type it is inheriting* *from; an alias.  Otherwise, the base type's put and/or get routines will* *be overridden.*

*NOTE: The typname member of the PGregisterType structure can optionally* *contain the type's schema: schema.typname.*

*WARNING: PQparamCreate is only aware of types that have already been* *registered.  If you need to put a type into a param, make sure it is first* *registered.*

## RETURN VALUE

*On success, a non-zero value is returned.  On error, zero is* *returned and [PQgeterror(3)](/PQgeterror/3.md) will contain an error message.*

## EXAMPLES

*None.*

## AUTHOR

*A contribution of eSilo, LLC. for the PostgreSQL Database Management System.* *Written by Andrew Chernow and Merlin Moncure.*

## REPORTING BUGS

*Report bugs to \<libpqtypes@esilo.com\>.*

## COPYRIGHT

*Copyright (c) 2011 eSilo, LLC. All rights reserved.*\
 *This is free software; see the source for copying conditions.* *There is NO warranty; not even for MERCHANTABILITY or  FITNESS* *FOR A PARTICULAR PURPOSE.*

## SEE ALSO

*[pqt-handlers(3)](/pqt-handlers/3.md), [PQputf(3)](/PQputf/3.md), [PQgetf(3)](/PQgetf/3.md)*