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Client APIs and toolsYou can use the HCL OneDB™ implementation of client APIs to develop applications for HCL OneDB™ database servers.
ESQL/C GuideThe HCL OneDB™ ESQL/C Programmer's Manual explains how to use , the HCL OneDB™ implementation of Embedded Structured Query Language (SQL) for C (ESQL/C), to create client applications with database-management capabilities.
Dynamic SQL
A system-descriptor areaA system-descriptor area is a dynamic-management structure that can hold data that a prepared statement either returns from or sends to the database server. A system-descriptor area conforms to X/Open standards.
Manage a system-descriptor area

Manage a system-descriptor area

Your program can manipulate a system-descriptor area with the SQL statements that the following tables summarize.

Table 1. SQL statements that can be used to manipulate a system-descriptor area
SQL statement	Purpose	See
ALLOCATE DESCRIPTOR	Allocates memory for a system-descriptor area	Allocate memory for a system-descriptor area
DESCRIBE...USING SQL DESCRIPTOR	Initializes the system-descriptor area with information about column-list columns	Initialize the system-descriptor area
GET DESCRIPTOR	Obtains information from the fields of the system-descriptor area	Assign and obtain values from a system-descriptor area
SET DESCRIPTOR	Places information into a system- descriptor area for the database server to access	Assign and obtain values from a system-descriptor area

Table 2. SQL statements that can be used to manipulate a system-descriptor area: SELECT and EXECUTE FUNCTION statements that use cursors
SQL statement	Purpose	See
OPEN...USING SQL DESCRIPTOR FETCH...USING SQL DESCRIPTOR	Takes any input parameters from the specified system-descriptor area Puts the contents of the row into the system-descriptor area	Specify input parameter values Put column values into a system-descriptor area

Table 3. SQL statements that can be used to manipulate a system-descriptor area: SELECT and EXECUTE FUNCTION statements that return only one row
SQL statement	Purpose	See
EXECUTE...INTO SQL DESCRIPTOR	Puts the contents of the singleton row into the system-descriptor area	Put column values into a system-descriptor area

Table 4. SQL statements that can be used to manipulate a system-descriptor area: non-SELECT statements:
SQL statement	Purpose	See
EXECUTE...USING SQL DESCRIPTOR	Takes any input parameters from the specified system-descriptor area	Specify input parameter values

Table 5. SQL statements that can be used to manipulate a system-descriptor area: an INSERT statement that uses an insert cursor:
SQL statement	Purpose	See
PUT...USING SQL DESCRIPTOR	Puts a row into the insert buffer, obtaining the column values from the specified system-descriptor area	Handling an unknown column list
DEALLOCATE DESCRIPTOR	Frees memory allocated for the system-descriptor area when your program is finished with it	Free memory allocated to a system-descriptor area