# The OCI8 Extension

Use the OCI8 extension to access Oracle Database.

Documentation is at https://www.php.net/oci8

Use `pecl install oci8` to install for PHP 7.

Use `pecl install oci8-2.0.12` to install for PHP 5.2 - PHP 5.6.

Use `pecl install oci8-1.4.10` to install for PHP 4.3.9 - PHP 5.1.

The OCI8 extension needs to be linked with Oracle 18, 12, 11, or 10.2 client
libraries. These libraries are found in your database installation, or in the
free Oracle Instant Client from
https://www.oracle.com/technetwork/database/database-technologies/instant-client/overview/index.html
Install the 'Basic' or 'Basic Light' Instant Client package. If building from
source, then also install the SDK package.

Oracle's standard cross-version interoperability applies. For example, PHP OCI8
linked with Instant Client 11.2 can connect to Oracle Database 9.2 onward. See
Oracle's note "Oracle Client / Server Interoperability Support" (ID 207303.1)
for details.