The TPDORowKeyStrings type is just a TStringList. Fetched rows returned in this structure are keyed: Column Name / Value. So if a query returns five columns, the TPDORowKeyStrings variable will be a list of five strings.
There are many benefits to this:
- Its known that all fields are strings
- Many functions and controls accept TStringLists natively
- The columns can be sorted within the list
- Field values can be retrieved by the column name
- Field values can be retrieved by the column position in the query
- Column counts are built-in via TStringList.count
- Column names can be returned by index or field value
- and others
This structure is an object that is essentially an array of TPDORowKeyStrings (TStringLists). The TPDO.fetch_all method can return an entire result set and place it into this structure.
Both TPDORowKeyStrings and TPDORowSetKeyStrings objects must be instanciated and freed.