oci_pconnect() creates a new persistent connection to an Oracle server and logs on. The optional third parameter can either contain the name of the local Oracle instance or the name of the entry in tnsnames.ora. If the third parameter is not specified, PHP uses environment variables ORACLE_SID and TWO_TASK to determine the name of local Oracle instance and location of tnsnames.ora accordingly.
使用 Oracle 服务器 9.2 或更高版本，可以指定 charset 参数，其将被用于新的连接。如果使用 Oracle 服务器低于 9.2 的版本，本参数将被忽略并以 NLS_LANG 环境变量替代之。
oci_pconnect() returns connection identifier or FALSE on error.
注: Note, that these kind of links only work if you are using a module version of PHP. See the Persistent Database Connections section for more information.
注: In PHP versions before 5.0.0 you must use ociplogon() instead. This name still can be used, it was left as alias of oci_pconnect() for downwards compatability. This, however, is deprecated and not recommended.
See also oci_connect() and oci_new_connect().