Introduction

Cursor variables and dynamic cursors are powerful features in DB2 that allow you to work with result sets in a more flexible and dynamic manner. In this blog post, we will dive into the usage of these features and understand how they can be beneficial in different scenarios.

Cursor Variables

Cursor variables, also known as looper cursors, can be used to iterate over result sets in a dynamic and efficient way. Instead of explicitly declaring and opening a cursor for a specific query, cursor variables allow you to dynamically bind different queries to the same cursor variable and iterate over the results.

To declare a cursor variable, you can use the DECLARE statement followed by the CURSOR keyword and assign it a specific result set using the FOR keyword:

DECLARE cursor_var CURSOR FOR SELECT * FROM employees;

Once the cursor variable is declared, you can open it with the OPEN statement and fetch the rows using the FETCH statement:

OPEN cursor_var;
FETCH NEXT FROM cursor_var INTO :host_variable1, :host_variable2;

Cursor variables provide flexibility as they allow you to change the query associated with the cursor variable at runtime, thus eliminating the need to declare multiple cursors for different scenarios.

Dynamic Cursors

Dynamic cursors, on the other hand, are useful in scenarios where you need to construct the SQL query dynamically at runtime. They allow you to build and execute SQL statements dynamically based on the given conditions.

To use dynamic cursors, you need to declare a cursor with the DYNAMIC keyword:

DECLARE cursor_name DYNAMIC SCROLL CURSOR FOR SQLSTATEMENT;

Once the dynamic cursor is declared, you can use the PREPARE statement to build the SQL statement dynamically:

PREPARE stmt FROM :sql_statement;

After preparing the statement, you can open the dynamic cursor and fetch the rows:

OPEN cursor_name;
FETCH NEXT FROM cursor_name INTO :host_variable1, :host_variable2;

Dynamic cursors offer great flexibility as they allow you to construct the SQL statement based on runtime conditions, making your queries more dynamic and adaptable.

Conclusion

Cursor variables and dynamic cursors in DB2 provide powerful capabilities to work with result sets in a dynamic manner. Cursor variables allow you to dynamically bind different queries to the same cursor variable and iterate over the results, while dynamic cursors enable you to construct and execute SQL statements dynamically at runtime. Understanding and utilizing these features properly can greatly enhance your ability to work with result sets in DB2.

#DB2 #CursorVariables #DynamicCursors