With the MODIFY and Maintain facilities, you can add new rows to a table, update column values for specific rows, or delete specific rows.

The adapter processes a MODIFY or Maintain transaction with the following steps:

1. FOCUS reads the transaction for incoming data values.
2. The adapter generates the appropriate SQL SELECT statement.
3. The RDBMS either returns an answer set consisting of one or more rows that satisfy the SELECT request, or determines that the row does not exist.
4. After the RDBMS returns the answer set and/or return code, the adapter either:
   • Performs the update operation (UPDATE or DELETE) on the returned answer set. With MODIFY, the adapter processes one row at a time. With Maintain, it can either process one row at a time or a set of rows.
   • Creates the new row (INCLUDE). In Maintain, it may create multiple rows.
5. The RDBMS changes the data source appropriately.

In MODIFY, you must use the NEXT command to process a multi-row answer set one row at a time. Each NEXT command puts you physically at the next logical row in the answer set. In Maintain, one NEXT command can process a multi-row answer set without a prior MATCH.