Difference between revisions of "OpenDBX/C API/odbx get option"
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= Description = | = Description = | ||
| − | '''odbx_get_option()''' asks the backend module associated to '''handle''' by [[OpenDBX_init|odbx_init()]] for implemented options and their current values. This function can be used | + | '''odbx_get_option()''' asks the backend module associated to '''handle''' by [[OpenDBX_init|odbx_init()]] for implemented options and their current values. This function can be used at every stage as long as '''handle''' points to a valid connection object. Its primary use is to find out supported features of the backend module and to enable them with [[OpenDBX_set_option|odbx_set_option()]] before the connection to the database server is established by calling [[OpenDBX_bind|odbx_bind()]]. |
The first parameter '''handle''' is the connection object created and returned by [[OpenDBX_init|odbx_init()]] which becomes invalid as soon as it was supplied to [[OpenDBX_finish|odbx_finish()]]. | The first parameter '''handle''' is the connection object created and returned by [[OpenDBX_init|odbx_init()]] which becomes invalid as soon as it was supplied to [[OpenDBX_finish|odbx_finish()]]. | ||
| − | There are several '''options''' defined as named constants in the '''odbx.h''' header file. A few of them are for informational purpose only while most of the options can also be set to different values by [[OpenDBX_set_option|odbx_set_option()]] to change the behavior of the backend module. | + | There are several '''options''' defined as named constants in the '''odbx.h''' header file. A few of them are for informational purpose only while most of the options can also be set to different values by [[OpenDBX_set_option|odbx_set_option()]] to change the behavior of the backend module. The available options are: |
| − | + | ||
| − | + | ||
| − | + | ||
| − | The available options are: | + | |
; ODBX_OPT_API_VERSION : The API version implemented by the backend. Currently, it returns only zero and is reserved for the future. | ; ODBX_OPT_API_VERSION : The API version implemented by the backend. Currently, it returns only zero and is reserved for the future. | ||
; ODBX_OPT_THREAD_SAFE : If it is safe to use this backend and especially the native database client library in an application which uses threads where more than one thread opens database connections via the OpenDBX library | ; ODBX_OPT_THREAD_SAFE : If it is safe to use this backend and especially the native database client library in an application which uses threads where more than one thread opens database connections via the OpenDBX library | ||
| − | ; ODBX_OPT_TLS : The database client library may support | + | ; ODBX_OPT_TLS : The database client library may support transmitting all data securely by encrypting the network traffic via SSL or TLS |
| − | ; ODBX_OPT_MULTI_STATEMENTS : The database server may be able to support multiple statements in one query sent | + | ; ODBX_OPT_MULTI_STATEMENTS : The database server may be able to support multiple SQL statements in one query string sent via [[OpenDBX_query|odbx_query()]] |
| − | ; ODBX_OPT_PAGED_RESULTS : All database client libraries are able to transfer | + | ; ODBX_OPT_PAGED_RESULTS : All database servers and client libraries are able to transfer the records row by row. Some of them can also transfer multiple rows or even all at once to minimize server load, network traffic and latency. The downside of this is an increased memory consumption. |
| − | ; ODBX_OPT_COMPRESS : Support of compressed | + | ; ODBX_OPT_COMPRESS : Support of compressed network traffic between database client and server. This can lower the latency if the network is the bottleneck. |
| − | ; ODBX_OPT_MODE : | + | ; ODBX_OPT_MODE : Some database servers support different modes of operation, e.g. modes for compliance to other SQL implementations or completely different query languages. This option is available since OpenDBX 1.1.4 |
| + | |||
| + | '''value''' must be a pointer to an integer variable where the backend module will store the result for the supplied option. If it's not stated otherwise, the value assigned to the '''value''' parameter by '''odbx_get_option()''' will be of boolean nature and therefore will only consist of one ("1") for a supported option or zero ("0") for an option which isn't supported. | ||
= Return values = | = Return values = | ||
Revision as of 00:54, 2 March 2007
#include <odbx.h>
int odbx_get_option(
odbx_t* handle,
unsigned int option,
void* value )
Description
odbx_get_option() asks the backend module associated to handle by odbx_init() for implemented options and their current values. This function can be used at every stage as long as handle points to a valid connection object. Its primary use is to find out supported features of the backend module and to enable them with odbx_set_option() before the connection to the database server is established by calling odbx_bind().
The first parameter handle is the connection object created and returned by odbx_init() which becomes invalid as soon as it was supplied to odbx_finish().
There are several options defined as named constants in the odbx.h header file. A few of them are for informational purpose only while most of the options can also be set to different values by odbx_set_option() to change the behavior of the backend module. The available options are:
- ODBX_OPT_API_VERSION
- The API version implemented by the backend. Currently, it returns only zero and is reserved for the future.
- ODBX_OPT_THREAD_SAFE
- If it is safe to use this backend and especially the native database client library in an application which uses threads where more than one thread opens database connections via the OpenDBX library
- ODBX_OPT_TLS
- The database client library may support transmitting all data securely by encrypting the network traffic via SSL or TLS
- ODBX_OPT_MULTI_STATEMENTS
- The database server may be able to support multiple SQL statements in one query string sent via odbx_query()
- ODBX_OPT_PAGED_RESULTS
- All database servers and client libraries are able to transfer the records row by row. Some of them can also transfer multiple rows or even all at once to minimize server load, network traffic and latency. The downside of this is an increased memory consumption.
- ODBX_OPT_COMPRESS
- Support of compressed network traffic between database client and server. This can lower the latency if the network is the bottleneck.
- ODBX_OPT_MODE
- Some database servers support different modes of operation, e.g. modes for compliance to other SQL implementations or completely different query languages. This option is available since OpenDBX 1.1.4
value must be a pointer to an integer variable where the backend module will store the result for the supplied option. If it's not stated otherwise, the value assigned to the value parameter by odbx_get_option() will be of boolean nature and therefore will only consist of one ("1") for a supported option or zero ("0") for an option which isn't supported.
Return values
- ODBX_ERR_SUCCESS on success
- Less than zero if an error occured
Errors
- -ODBX_ERR_PARAM: "handle" is NULL or the structure is invalid
- -ODBX_ERR_OPTION: Unknown option
See also
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