This function returns a single value - being the first field in an aSQL query.
It would be more common to use the GetDataSetFromDest function to return multiple values - this saves re-querying the database to retrieve multiple fields from a single record.
The SQL query is executed against a DB Connection on the Destination of the Map.
aDBIndex indicates which of the DB Connections is used based on its zero based index.
Declaration: function GetSQLValueFromDest(const aSQL: string; aDBIndex : integer): variant;
The example follows.
procedure OnMapEvent(var Value:Variant);
begin
Value := GetSQLValueFromDest('select name from dr_accs where accno=1',0);