以下常量由本扩展模块定义，因此只有在本扩展模块被编译到 PHP 中，或者在运行时被动态加载后才有效。
The following constants to use with maxdb_options() are defined. For further description of these constants see » http://maxdb.sap.com/documentation/.
| Constant | Description |
|---|---|
| MAXDB_COMPNAME | The component name used to initialise the SQLDBC runtime environment. |
| MAXDB_APPLICATION | The application to be connected to the database. |
| MAXDB_APPVERSION | The version of the application. |
| MAXDB_SQLMODE | The SQL mode. |
| MAXDB_UNICODE | TRUE, if the connection is an unicode (UCS2) client or FALSE, if not. |
| MAXDB_TIMEOUT | The maximum allowed time of inactivity after which the connection to the database is closed by the system. |
| MAXDB_ISOLATIONLEVEL | Specifies whether and how shared locks and exclusive locks are implicitly requested or released. |
| MAXDB_PACKETCOUNT | The number of different request packets used for the connection. |
| MAXDB_STATEMENTCACHESIZE | The number of prepared statements to be cached for the connection for re-use. |
| MAXDB_CURSORPREFIX | The prefix to use for result tables that are automatically named. |
The function maxdb_fetch_array() uses a constant for the different types of result arrays. The following constants are defined:
| Constant | Description |
|---|---|
| MAXDB_ASSOC | Columns are returned into the array having the fieldname as the array index. |
| MAXDB_ASSOC_UPPER | Columns are returned into the array having the upper case fieldname as the array index. |
| MAXDB_ASSOC_LOWER | Columns are returned into the array having the lower case fieldname as the array index. |
| MAXDB_BOTH | Columns are returned into the array having both a numerical index and the fieldname as the array index. |
| MAXDB_NUM | Columns are returned into the array having a numerical index to the fields. This index starts with 0, the first field in the result. |