Comparing DDE with ODBC

Extensibility > Exchanging Data with Other Applications > Using ODBC drivers > Comparing DDE with ODBC

Each has advantages and disadvantages. In general DDE is suitable for simple requirements but ODBC give serious thought if the limitations of DDE become too restrictive.

DDE Advantages

No need to set up a Data Service Name (DSN); however, a DDEShareName is necessary for Network DDE.
Can call Access Macros & Functions.

DDE Disadvantages

Record sets with rows that exceed the maximum Cicode string length cannot be read directly.
Rows (records) are returned to string variable with TAB characters between columns. You need to parse the string in Cicode to obtain the column (field) values.
SQL over DDE cannot perform actions (such as INSERT, UPDATE or DELETE).
DDE Client and server applications need to be be running at the same time.

ODBC Advantages

MS Access does not have to be running. ODBC uses the JET Engine DLL on the same PC. This an advantage in many ways but can consume excessive PC resources if not managed properly.
Large SQL statements can be split into sub-strings.
SQLGetField makes easier to get data from fields (columns). There is no need to parse the data in Cicode.
Can handle large numbers of fields (columns) in the Recordset.
SQL can perform actions (such as INSERT, UPDATE or DELETE).

ODBC Disadvantages

Requires that a Data Service Name (DSN) be set up.

The JET Engine DLL cannot be directly called on a remote PC, (Reports or MsgRPC() can be used however, to run SQL statements on a Remote Computer which needs to be be running Citect SCADA).