---
title: "ECPG — Embedded SQL in C"
id: ecpg
pg_version: "20devel"
---

<a id="ecpg"></a>

# ECPG — Embedded SQL in C

## Table of Contents

- [34.1. The Concept](ecpg-concept.md)
- [34.2. Managing Database Connections](ecpg-connect.md)
  - [34.2.1. Connecting to the Database Server](ecpg-connect.md#ecpg-connecting)
  - [34.2.2. Choosing a Connection](ecpg-connect.md#ecpg-set-connection)
  - [34.2.3. Closing a Connection](ecpg-connect.md#ecpg-disconnect)
- [34.3. Running SQL Commands](ecpg-commands.md)
  - [34.3.1. Executing SQL Statements](ecpg-commands.md#ecpg-executing)
  - [34.3.2. Using Cursors](ecpg-commands.md#ecpg-cursors)
  - [34.3.3. Managing Transactions](ecpg-commands.md#ecpg-transactions)
  - [34.3.4. Prepared Statements](ecpg-commands.md#ecpg-prepared)
- [34.4. Using Host Variables](ecpg-variables.md)
  - [34.4.1. Overview](ecpg-variables.md#ecpg-variables-overview)
  - [34.4.2. Declare Sections](ecpg-variables.md#ecpg-declare-sections)
  - [34.4.3. Retrieving Query Results](ecpg-variables.md#ecpg-retrieving)
  - [34.4.4. Type Mapping](ecpg-variables.md#ecpg-variables-type-mapping)
  - [34.4.5. Handling Nonprimitive SQL Data Types](ecpg-variables.md#ecpg-variables-nonprimitive-sql)
  - [34.4.6. Indicators](ecpg-variables.md#ecpg-indicators)
- [34.5. Dynamic SQL](ecpg-dynamic.md)
  - [34.5.1. Executing Statements without a Result Set](ecpg-dynamic.md#ecpg-dynamic-without-result)
  - [34.5.2. Executing a Statement with Input Parameters](ecpg-dynamic.md#ecpg-dynamic-input)
  - [34.5.3. Executing a Statement with a Result Set](ecpg-dynamic.md#ecpg-dynamic-with-result)
- [34.6. pgtypes Library](ecpg-pgtypes.md)
  - [34.6.1. Character Strings](ecpg-pgtypes.md#ecpg-pgtypes-cstrings)
  - [34.6.2. The numeric Type](ecpg-pgtypes.md#ecpg-pgtypes-numeric)
  - [34.6.3. The date Type](ecpg-pgtypes.md#ecpg-pgtypes-date)
  - [34.6.4. The timestamp Type](ecpg-pgtypes.md#ecpg-pgtypes-timestamp)
  - [34.6.5. The interval Type](ecpg-pgtypes.md#ecpg-pgtypes-interval)
  - [34.6.6. The decimal Type](ecpg-pgtypes.md#ecpg-pgtypes-decimal)
  - [34.6.7. errno Values of pgtypeslib](ecpg-pgtypes.md#ecpg-pgtypes-errno)
  - [34.6.8. Special Constants of pgtypeslib](ecpg-pgtypes.md#ecpg-pgtypes-constants)
- [34.7. Using Descriptor Areas](ecpg-descriptors.md)
  - [34.7.1. Named SQL Descriptor Areas](ecpg-descriptors.md#ecpg-named-descriptors)
  - [34.7.2. SQLDA Descriptor Areas](ecpg-descriptors.md#ecpg-sqlda-descriptors)
- [34.8. Error Handling](ecpg-errors.md)
  - [34.8.1. Setting Callbacks](ecpg-errors.md#ecpg-whenever)
  - [34.8.2. sqlca](ecpg-errors.md#ecpg-sqlca)
  - [34.8.3. `SQLSTATE` vs. `SQLCODE`](ecpg-errors.md#ecpg-sqlstate-sqlcode)
- [34.9. Preprocessor Directives](ecpg-preproc.md)
  - [34.9.1. Including Files](ecpg-preproc.md#ecpg-include)
  - [34.9.2. The define and undef Directives](ecpg-preproc.md#ecpg-define)
  - [34.9.3. ifdef, ifndef, elif, else, and endif Directives](ecpg-preproc.md#ecpg-ifdef)
- [34.10. Processing Embedded SQL Programs](ecpg-process.md)
- [34.11. Library Functions](ecpg-library.md)
- [34.12. Large Objects](ecpg-lo.md)
- [34.13. C++ Applications](ecpg-cpp.md)
  - [34.13.1. Scope for Host Variables](ecpg-cpp.md#ecpg-cpp-scope)
  - [34.13.2. C++ Application Development with External C Module](ecpg-cpp.md#ecpg-cpp-and-c)
- [34.14. Embedded SQL Commands](ecpg-sql-commands.md)
  - [ALLOCATE DESCRIPTOR](ecpg-sql-allocate-descriptor.md)
  - [CONNECT](ecpg-sql-connect.md)
  - [DEALLOCATE DESCRIPTOR](ecpg-sql-deallocate-descriptor.md)
  - [DECLARE](ecpg-sql-declare.md)
  - [DECLARE STATEMENT](ecpg-sql-declare-statement.md)
  - [DESCRIBE](ecpg-sql-describe.md)
  - [DISCONNECT](ecpg-sql-disconnect.md)
  - [EXECUTE IMMEDIATE](ecpg-sql-execute-immediate.md)
  - [GET DESCRIPTOR](ecpg-sql-get-descriptor.md)
  - [OPEN](ecpg-sql-open.md)
  - [PREPARE](ecpg-sql-prepare.md)
  - [SET AUTOCOMMIT](ecpg-sql-set-autocommit.md)
  - [SET CONNECTION](ecpg-sql-set-connection.md)
  - [SET DESCRIPTOR](ecpg-sql-set-descriptor.md)
  - [TYPE](ecpg-sql-type.md)
  - [VAR](ecpg-sql-var.md)
  - [WHENEVER](ecpg-sql-whenever.md)
- [34.15. Informix Compatibility Mode](ecpg-informix-compat.md)
  - [34.15.1. Additional Types](ecpg-informix-compat.md#ecpg-informix-types)
  - [34.15.2. Additional/Missing Embedded SQL Statements](ecpg-informix-compat.md#ecpg-informix-statements)
  - [34.15.3. Informix-compatible SQLDA Descriptor Areas](ecpg-informix-compat.md#ecpg-informix-sqlda)
  - [34.15.4. Additional Functions](ecpg-informix-compat.md#ecpg-informix-functions)
  - [34.15.5. Additional Constants](ecpg-informix-compat.md#ecpg-informix-constants)
- [34.16. Oracle Compatibility Mode](ecpg-oracle-compat.md)
- [34.17. Internals](ecpg-develop.md)

This chapter describes the embedded SQL package for PostgreSQL. It was written by Linus Tolke (<linus@epact.se>) and Michael Meskes (<meskes@postgresql.org>). Originally it was written to work with C. It also works with C++, but it does not recognize all C++ constructs yet. 

This documentation is quite incomplete. But since this interface is standardized, additional information can be found in many resources about SQL.