Cursor

To work on a subset of rows from a query, Phoenix supports a CURSOR control structure. The sequence below shows how to use a cursor.

Using a cursor

1. Define a cursor for a query using the DECLARE statement.

   PreparedStatement statement = conn.prepareStatement(
       "DECLARE empCursor CURSOR FOR SELECT * FROM EMP_TABLE"
   );
   statement.execute();

2. Open the cursor.

   statement = conn.prepareStatement("OPEN empCursor");
   statement.execute();

3. Fetch a subset of rows to work with.

   statement = conn.prepareStatement("FETCH NEXT 10 ROWS FROM empCursor");
   ResultSet rset = statement.executeQuery();

4. Iterate through the fetched rows and process them as required.

   while (rset.next()) {
       // ...
   }

5. Fetch additional sets of rows as needed, and close the cursor when done.

   statement = conn.prepareStatement("CLOSE empCursor");
   statement.execute();