EDS is based on Microsoft's ODBC standard, which defines conformance levels for database drivers. These conformance levels help application developers by establishing standard sets of functionality. To claim that it conforms to a given conformance level, a driver must support all the functionality in that conformance level, regardless of whether that functionality is supported by the DBMS associated with the driver. However, conformance levels do not restrict drivers to the functionality in the levels to which they conform.
EDS uses the ODBC set of Core commands and two extended sets of functionality: Level 1 and Level 2. The following list summarizes the functionality included in each conformance level.
Core API
•Allocate and free environment, connection, and statement handles.
•Connect to data sources. Use multiple statements on a connection.
•Prepare and execute SQL statements. Execute SQL statements immediately.
•Assign storage for parameters in a SQL statement and result columns.
•Retrieve data from a result set. Retrieve information about a result set.
•Commit or roll back transactions.
•Retrieve error information.
Level 1 API
•Provide Core API functionality.
•Connect to data sources with driver-specific dialog boxes.
•Set and inquire values of statement and connection options.
•Send part or all of a parameter value (useful for long data).
Level 2 API
•Retrieve part or all of a result column value (useful for long data).
•Retrieve catalog information (columns, special columns, statistics, and tables).
•Retrieve information about driver and data source capabilities, such as supported data types, scalar functions, and ODBC functions.
•Provide Core and Level 1 API functionality.
•Browse available connections and list available data sources.
•Send arrays of parameter values. Retrieve arrays of result column values.
•Retrieve the number of parameters and describe individual parameters.
•Use a scrollable cursor.
•Retrieve the native form of a SQL statement.
•Retrieve catalog information (privileges, keys, and procedures).
•Call a translation DLL.
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EDS High Level Commands
EDS also includes a group of its own High Level commands, which are based on commonly used combinations of Core commands. The following list summarizes this functionality:
•Connect via an alternative high-level routine.
•Bind results with an ESL structure variable.
•Disconnect a connection via an alternative high-level routine.
•Shut down the EDS environment via an alternative high-level routine.
Each command description in this manual indicates whether the function is a Core command, a Level 1 or Level 2 extension command, or an EDS High Level command.
Note: ESL programs that call EDS functions must include the EDS.INC include file. In addition, ESL applications that call Level 1 or Level 2 functions must include the EDSEXT.INC include file.
