The main difference between IN and EXISTS in Oracle is that the SQL engine compares all values in the IN condition while the SQL engine stops the process as soon as finding a single positive condition in EXISTS.
Oracle database is an RDBMS designed by Oracle Corporation. It is commonly used in data warehousing and online transaction processing. The new version of Oracle, which is Oracle 19c, is available on cloud or in a hybrid cloud environment. Programmers can write SQL queries to perform operations on the data stored in the database. IN and EXISTS are two commands or conditions we can use when writing SQL queries.
Key Areas Covered
EXISTS, IN, Oracle, SQL
What is IN in Oracle
IN is a condition in Oracle that allows filtering the data in the WHERE clause. It helps to limit the data. Furthermore, it avoids using multiple OR clauses in the SQL statement. Furthermore, the statement with IN makes the query simpler.
The syntax is as follows. The expression denotes the name of the column to obtain values.
Expression IN (value1, value2, …., value n)
For example, assume a table called student. The SQL statement with ‘IN’ is as follows.
SELECT * from student WHERE name IN (‘Ann’, ‘Peter’, ‘Tom’);
It will provide the records that have the names Ann, Peter and Tom. In other words, it gives the values of all the columns in the table in which the names are ‘Ann’ or ‘Peter’ or ‘Tom’.
What is EXISTS in Oracle
The EXISTS is a condition that is used to combine queries and create subquery.
The syntax is as follows. The subquery denotes a select statement which returns at least one record.
WHERE EXISTS (subquery)
For example, table1 and table2 are two tables. The SQL statement with EXISTS is as follows.
SELECT name from table1 WHERE EXISTS (SELECT * FROM table2 WHERE table1.id = table2.id)
It will give a list of names from table1 after executing the query inside the braces.
Difference Between IN and EXISTS in Oracle
IN is a clause or a condition that helps to minimize the use of multiple OR conditions in Oracle while EXISTS is a clause or a condition that is used to combine the queries and create subquery in Oracle.
SQL engine compares all values in the IN condition. On the other hand, the SQL engine stops the process as soon as finding a single positive condition in EXISTS.
Moreover, IN is faster than EXISTS if the sub-query result is less whereas EXISTS is faster than IN if the sub-query result is large.
IN helps to compare null while EXISTS cannot be used to compare null.
The negation of IN is NOT IN while negation of EXISTS is NOT EXISTS.
Parent and subquery
IN compares values between parent query and sub-query while EXISTS cannot compare values between parent query and sub-query.
Furthermore, IN condition can have multiple direct values instead of a subquery. On the other hand, EXISTS condition cannot compare direct values. It should have a subquery with select.
IN is used as multiple OR operator whereas EXISTS helps to find whether any value is returned or not.
Oracle is a popular database management system. Programmer can write various queries to perform operations on the data stored in the databases. In brief, the two conditions available in Oracle are IN and EXISTS. The main difference between IN and EXISTS in Oracle is that the SQL engine compares all values in the IN condition while SQL engine stops the process as soon as finding a single positive condition in EXISTS.
1.”The logo of Oracle Corporation” By Oracle Corporation – the German Wikipedia where it was uploaded by Afrank99 (Public Domain) via Commons Wikimedia