Advantage SQL Engine
In the current implementation, the input parameters to a stored procedure can only be access through the __input table, and the output parameters of a stored procedure can only be returned through the __output table. For example, the following stored procedure concatenates a string to itself until it reaches the required length.
CREATE PROCEDURE testproc( str char( 20 ), len integer, strResult memo OUTPUT )
DECLARE strVal String, len Integer;
strVal = ( SELECT trim( str ) FROM __input );
len = ( SELECT len FROM __input );
WHILE length( strVal ) < len DO
strVal = strVal + strVal;
INSERT INTO __output VALUES ( strVal );
Recursion, executing a stored procedure within another stored procedure, is allowed by the Advantage SQL engine. However, the current implementation of recursive execution of stored procedures in the SQL engine is not optimized for memory usage. Care must be taken to ensure that the depth of the recursion is limited as much as possible. The maximum depth of recursion before the database server develops serious errors is dependant on the size and the complexity of the stored procedure being executed recursively. However, a recursion depth of 10 or more executions should generally be avoided. Using a loop instead of recursion will provide a more effective use of server resources.
Free tables can be used in SQL Script stored procedures. However, since there is no way to specify the table type for tables used in the stored procedure, only ADT free tables can be used in SQL Script stored procedures. To use DBF tables in a script-stored procedure, the tables must be database tables.