Difference Between EXISTS vs IN Operator

Setup Environment

For the demonstration in the following sections, I will first create an employee table and insert some values in it. The following query first creates an employee table that contains information such as id, name, Oracle develops it, and manager_id. Later in the query I inserted some sample data in the table....

IN Condition

In PL/SQL, the IN condition is a logical condition used in queries to specify a range of values. It is commonly used in the WHERE clause of a SELECT, UPDATE, DELETE, or MERGE statement to filter rows based on a specific list of values. Using the IN condition can make queries more concise and readable, especially when dealing with multiple values or subqueries....

EXISTS Condition

In PL/SQL, the EXISTS condition is a Boolean condition that tests for the existence of rows in a subquery. It returns TRUE if the subquery returns at least one row, otherwise it returns FALSE. The EXISTS condition is commonly used with the WHERE clause to filter rows based on the result of a subquery. It’s useful for checking the existence of related records before performing certain operations such as INSERT, UPDATE, or DELETE....

Difference Between EXISTS vs IN Operator

Let’s understood what IN and EXISTS condition are, let us now understand the differences between the two....

Technical Example

Let’s go through a technical example to solidify our understanding. We are going to make use of the above table and the records in them. Just for completion the following is the statement used to create the table and insert the records....

Conclusion

In this article we went through IN and EXISTS operators and understood what they are actually. We also looked at the differences between them and we finally wrapped the article with a technical example giving a sense of how we can use the concepts we learned in this article in real-life. While both operators are essential for filtering data and differs in terms of performance and handling NULL values. EXISTS is more efficient when dealing with large result sets, whereas IN may be faster for smaller sets. Moreover, EXISTS can evaluate NULL values without requiring special handling, unlike IN, which may need explicit filtering to avoid unexpected results....