DBdefine

Synopsis

Define user buffers for data returned by the select query.

Input Ports

ptr dbvisual_connect_descriptor – connection to database engine

ptr dbquery_descriptor – executed query handle with select list description

int process_statement – trigger to invoke the method

Output Ports

ptr dbvisual_connect_descriptor – connection to database engine

ptr dbquery_descriptor – executed query handle with pointer to user buffers

int done – finished processing? Can be used as a trigger to downstream modules

Description

DBdefine receives the select list description and allocates user buffers to retrieve one row of data according to the type information received.

Validation of connection and statement handle is the first task. If valid, the module queries the statement handle for parameters describing each select list item for their name and internal type. For each parameter, appropriate sized user buffers are allocated for retrieval. If either the connection handle or the statement handle is NULL and process_statement is set, this module will display an error message. If the statement handle has not been “executed”, an appropriate error message will be displayed.