What is the usage of OPEN CURSOR command?

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If you use the OPEN CURSOR command with ORDER BY clause, the rows are fetched, sorted and made available for the FETCH statement. Otherwise simply the cursor is placed on the first row.

In the context of DB2, the OPEN CURSOR command is used to prepare a cursor for processing. When you issue the OPEN CURSOR command, it makes the result set associated with the cursor available for fetching rows.

Here’s a breakdown of how the OPEN CURSOR command is typically used:

  1. DECLARE CURSOR: First, you declare a cursor using the DECLARE CURSOR statement. This statement defines the SELECT statement and associates it with the cursor.
    DECLARE cursor_name CURSOR FOR SELECT column1, column2 FROM your_table WHERE some_condition;
  2. OPEN CURSOR: After declaring the cursor, you use the OPEN CURSOR statement to prepare the result set for processing. This involves executing the SELECT statement and making the rows available for fetching.
    OPEN cursor_name;
  3. FETCH: Once the cursor is open, you can use the FETCH statement to retrieve rows one at a time from the result set.
    FETCH cursor_name INTO variable1, variable2;
  4. CLOSE CURSOR: After processing the result set, you should close the cursor using the CLOSE CURSOR statement.
    CLOSE cursor_name;

The OPEN CURSOR command, therefore, plays a crucial role in the lifecycle of a cursor, allowing you to start fetching rows from the result set.