PHP 5, PHP 7, PHP 8, PECL OCI8 >= 1.1.0
oci_connect - Connect to an Oracle database
Code Examples

     [string|null$connection_string = null],
     [string$encoding = ""],
     [int$session_mode = OCI_DEFAULT]
): resource|false

Returns a connection identifier needed for most other OCI8 operations.

For performance, most applications should use persistent connections with oci_pconnect instead of oci_connect. See Connection Handling for general information on connection management and connection pooling.

From PHP 5.1.2 (PECL OCI8 1.1) oci_close can be used to close the connection.

The second and subsequent calls to oci_connect with the same parameters will return the connection handle returned from the first call. This means that transactions in one handle are also in the other handles, because they use the same underlying database connection. If two handles need to be transactionally isolated from each other, use oci_new_connect instead.



The Oracle user name.


The password for username.

Contains the Oracle instance to connect to. It can be an Easy Connect string, or a Connect Name from the tnsnames.ora file, or the name of a local Oracle instance.

If not specified or null, PHP uses environment variables such as TWO_TASK (on Linux) or LOCAL (on Windows) and ORACLE_SID to determine the Oracle instance to connect to.

To use the Easy Connect naming method, PHP must be linked with Oracle 10g or greater Client libraries. The Easy Connect string for Oracle 10g is of the form: [//]host_name[:port][/service_name]. From Oracle 11g, the syntax is: [//]host_name[:port][/service_name][:server_type][/instance_name]. Further options were introduced with Oracle 19c, including timeout and keep-alive settings. Refer to Oracle documentation. Service names can be found by running the Oracle utility lsnrctl status on the database server machine.

The tnsnames.ora file can be in the Oracle Net search path, which includes /your/path/to/instantclient/network/admin, $ORACLE_HOME/network/admin and /etc. Alternatively set TNS_ADMIN so that $TNS_ADMIN/tnsnames.ora is read. Make sure the web daemon has read access to the file.


Determines the character set used by the Oracle Client libraries. The character set does not need to match the character set used by the database. If it doesn't match, Oracle will do its best to convert data to and from the database character set. Depending on the character sets this may not give usable results. Conversion also adds some time overhead.

If not specified, the Oracle Client libraries determine a character set from the NLS_LANG environment variable.

Passing this parameter can reduce the time taken to connect.


This parameter is available since version PHP 5 (PECL OCI8 1.1) and accepts the following values: OCI_DEFAULT, OCI_SYSOPER and OCI_SYSDBA. If either OCI_SYSOPER or OCI_SYSDBA were specified, this function will try to establish privileged connection using external credentials. Privileged connections are disabled by default. To enable them you need to set oci8.privileged_connect to On.

PHP 5.3 (PECL OCI8 1.3.4) introduced the OCI_CRED_EXT mode value. This tells Oracle to use External or OS authentication, which must be configured in the database. The OCI_CRED_EXT flag can only be used with username of "/" and a empty password. oci8.privileged_connect may be On or Off.

OCI_CRED_EXT may be combined with the OCI_SYSOPER or OCI_SYSDBA modes.

OCI_CRED_EXT is not supported on Windows for security reasons.

Return Values

Returns a connection identifier or false on error.



An incorrectly installed or configured OCI8 extension will often manifest itself as a connection problem or error. See Installing/Configuring for troubleshooting information.


Version Description
8.0.0, PECL OCI8 3.0.0 connection_string is now nullable.

Related Functions

Example of oci_connect

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PHP Version:

Function oci_connect:

Oracle OCI8 Functions

Most used PHP functions