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 can be passed to ibase_trans() to specify transaction behaviour.
| Constant | Description |
|---|---|
| IBASE_DEFAULT | The default transaction settings are to be used. This default is determined by the client library, which defines it as IBASE_WRITE|IBASE_CONCURRENCY|IBASE_WAIT in most cases. |
| IBASE_READ | Starts a read-only transaction. |
| IBASE_WRITE | Starts a read-write transaction. |
| IBASE_CONSISTENCY | Starts a transaction with the isolation level set to 'consistency', which means the transaction cannot read from tables that are being modified by other concurrent transactions. |
| IBASE_CONCURRENCY | Starts a transaction with the isolation level set to 'concurrency' (or 'snapshot'), which means the transaction has access to all tables, but cannot see changes that were committed by other transactions after the transaction was started. |
| IBASE_COMMITTED | Starts a transaction with the isolation level set to 'read committed'. This flag should be combined with either IBASE_REC_VERSION or IBASE_REC_NO_VERSION. This isolation level allows access to changes that were committed after the transaction was started. If IBASE_REC_NO_VERSION was specified, only the latest version of a row can be read. If IBASE_REC_VERSION was specified, a row can even be read when a modification to it is pending in a concurrent transaction. |
| IBASE_WAIT | Indicated that a transaction should wait and retry when a conflict occurs. |
| IBASE_NOWAIT | Indicated that a transaction should fail immediately when a conflict occurs. |
The following constants can be passed to ibase_fetch_row(), ibase_fetch_assoc() or ibase_fetch_object() to specify fetch behaviour.
| Constant | Description |
|---|---|
| IBASE_FETCH_BLOBS | Also available as IBASE_TEXTfor backward compatibility. Causes BLOB contents to be fetched inline, instead of being fetched as BLOB identifiers. |
| IBASE_FETCH_ARRAYS | Causes arrays to be fetched inline. Otherwise, array identifiers are returned. Array identifiers can only be used as arguments to INSERT operations, as no functions to handle array identifiers are currently available. |
| IBASE_UNIXTIME | Causes date and time fields not to be returned as strings, but as UNIX timestamps (the number of seconds since the epoch, which is 1-Jan-1970 0:00 UTC). Might be problematic if used with dates before 1970 on some systems. |
The following constants are used to pass requests and options to the service API functions (ibase_server_info(), ibase_db_info(), ibase_backup(), ibase_restore() and ibase_maintain_db()). Please refer to the Firebird/InterBase manuals for the meaning of these options.