---
title: "Catalog Functions | Microsoft Docs"
ms.custom: ""
ms.date: "01/19/2017"
ms.prod: sql
ms.prod_service: connectivity
ms.reviewer: ""
ms.technology: connectivity
ms.topic: conceptual
helpviewer_keywords: 
  - "catalog functions [ODBC], about catalog functions"
  - "data dictionary [ODBC]"
  - "catalog functions [ODBC]"
  - "functions [ODBC], catalog functions"
ms.assetid: 81ba9453-c085-47c0-b411-90ca6a5ee428
author: David-Engel
ms.author: v-daenge
---
# Catalog Functions
All databases have a structure that outlines how data will be stored in the database. For example, a simple sales order database might have the structure shown in the following illustration, in which the ID columns are used to link the tables.  
  
 ![Shows the structure of a simple database](../../../odbc/reference/develop-app/media/pr19.gif "pr19")  
  
 This structure, along with other information such as privileges, is stored in a set of system tables called the database's *catalog,* which is also known as a *data dictionary*.  
  
 An application can discover this structure through calls to the *catalog functions*. The catalog functions return information in result sets and are usually implemented through **SELECT** statements against the tables in the catalog. For example, an application might request a result set containing information about all the tables on the system or all the columns in a particular table.  
  
 This section contains the following topics.  
  
-   [Uses of Catalog Data](../../../odbc/reference/develop-app/uses-of-catalog-data.md)  
  
-   [Catalog Functions in ODBC](../../../odbc/reference/develop-app/catalog-functions-in-odbc.md)