Difference between IN and EXISTS in DB2

IN and EXISTS are both keywords used in SQL queries to filter data based on specified conditions. In DB2, there are key differences between the two:

1. IN: The IN keyword is used to specify a list of values that a column must match in order to be included in the result set. It is essentially a shorthand way of writing multiple OR conditions. For example:

   SELECT * FROM table_name WHERE column_name IN (value1, value2, value3);
   

   This query will return rows where the column_value matches any of the specified values in the list.

2. EXISTS: The EXISTS keyword is used to check for the existence of a record that meets a specific condition in a subquery. It returns true if the subquery returns any rows, otherwise false. For example:

   SELECT * FROM table_name WHERE EXISTS (SELECT * FROM another_table WHERE condition);
   

   This query will return rows from table_name where the subquery returns at least one row based on the specified condition.

Overall, the main difference between IN and EXISTS in DB2 is that IN is used to filter data based on a list of predefined values, while EXISTS is used to check for the existence of a record that meets a specific condition in a subquery.