executeupdate vs executequery vs execute

ResultSet executeQuery() – Used for reading the content of the database.
output will be in form of ResultSet.
eg – SELECT statement.

int executeUpdate() – Used for DML(altering the database).
output will be in int.
eg – DROP TABLE or DATABASE, INSERT into TABLE, UPDATE TABLE, DELETE from TABLE statements.

boolean execute() – Executing SQL statements.
output will be in boolean. TRUE indicates the result is a ResultSet and FALSE indicates it has the int value which denotes number of rows affected by the query.
eg – DROP TABLE or DATABASE, INSERT into TABLE, UPDATE TABLE, DELETE from TABLE statements.