| Oracle® Objects for OLE C++ Class Library Developer's Guide 10g Release 2 (10.2) Part Number B14308-01 |
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| Oracle® Objects for OLE C++ Class Library Developer's Guide 10g Release 2 (10.2) Part Number B14308-01 |
|
Applies To
Description
This method opens an OBinder object, making it useful.
Usage
OBinder: oresult Open(const char *dbname, const char *username, const char *pwd, const char *sqls, long dynopts)
OBinder: oresult Open(const ODatabase &odb, const char *sqls, long dynopts)
OBinder: oresult Open(const ODatabase &odb, const char *sqlstmt, unsigned int slicesize, unsigned int perblock, unsigned int blocks, unsigned int fetchlimit, unsigned int fetchsize, long options = ODYNASET_DEFAULT)
Arguments
| Arguments |
Description |
|---|---|
| dbname | The name of the database to which to connect. |
| username | The username to use to log in to the database. |
| pwd | The database password for the user username. |
| odb | The database with which you want to open the OBinder's dynaset. |
| sqls | A valid select SQL statement. |
| dynopts | Options to be used to create the dynaset. |
| sqlstmt | A valid select SQL statement. |
| options | Options to be used to create the dynaset. |
| slicesize | Cache slice size. |
| perblock | Cache slices for each block. |
| blocks | Cache maximum number of blocks. |
| fetchlimit | Fetch array size. |
| fetchsize | Fetch array buffer size. |
Remarks
To Open an OBinder object for work, you need to connect it to an Oracle database and select a set of records. Opening an OBinder object is like opening both an ODatabase and an ODynaset.
The OBinder object needs to connect to a database. You can supply the database directly with an ODatabase argument, or you can give the connection information: database name, username, and password. If you choose the latter method, note that the database will be created with ODATABASE_DEFAULT set for its options.
The third Open method opens the OBinder object using custom cache and fetch parameters.
The OBinder object also needs a dynaset. The dynaset is created using the database specified by the preceding arguments and by the sqlstmt and dynopts arguments. These arguments act identically as the arguments to an ODynaset Open. Note that whenever an OBinder opens a dynaset, it always moves immediately to the first record.
The dynopts argument can have the following values:
dynopts Argument Values
| Constant |
Value |
Description |
|---|---|---|
| ODYNASET_DEFAULT | 0 | Accept the default behavior. |
| ODYNASET_NOBIND | 1 | Do not perform automatic binding of database parameters. |
| ODYNASET_KEEP_BLANKS | 2 | Do not strip trailing blanks from character string data retrieved from the database. |
| ODYNASET_READONLY | 4 | Force dynaset to be read-only. |
| ODYNASET_NOCACHE | 8 | Do not create a local dynaset data cache. Without the local cache, previous rows within a dynaset are unavailable; however, increased performance results during retrieval of data from the database (move operations) and from the rows (field operations). Use this option in applications that make single passes through the rows of a dynaset for increased performance and decreased resource usage. |
Options may be combined by adding their respective values.
These values can be found in the file ORCL.H.
Open(OBinder) calls the PreQuery and PostQuery triggers. The OBinder Startup trigger will not be called until the first OBound object is bound to the OBinder.
It is legal (though unusual) to open an already open OBinder. The OBinder's dynaset is closed, then reopened. Note that this does not affect an OBinder's bound OBound objects - they are still bound.
If OBound objects are already bound to an OBinder, but do not represent valid column names in the SQL query, Open will fail. This can happen when OBound objects are bound prior to calling OBinder::Open or when opening an already open OBinder.
Return Value
An oresult indicating whether the operation succeeded (OSUCCESS) or not (OFAILURE).
Example
An example of setting up an OBinder object:
// construct the OBinder
OBinder empblock;
// we normally then bind OBound objects to the OBinder
// here we have several OBoundVal objects (see the Workbook)
OBoundVal salary;
OBoundVal ename;
// bind them
salary.BindToBinder(&empblock, "sal");
/*
That is the first thing bound, so the OBinder::Startup trigger is called.
*/
ename.BindToBinder(&empblock, "ename");
/*
The OBound::Startup trigger is called on each OBound as it is bound.
*/
// now open the OBinder
ODatabase odb("ExampleDB", "scott", "tiger"); // open the database
empblock.Open(odb, "select * from emp order by ename");
// that calls all the PreQuery and PostQuery triggers