Oracle / PLSQL: MINUS Operator

This Oracle tutorial explains how to use the Oracle MINUS operator with syntax and examples.

Description

The Oracle MINUS operator is used to return all rows in the first SELECT statement that are not returned by the second SELECT statement. Each SELECT statement will define a dataset. The MINUS operator will retrieve all records from the first dataset and then remove from the results all records from the second dataset.

Minus Query

Explanation: The MINUS query will return the records in the blue shaded area. These are the records that exist in Dataset1 and not in Dataset2.

Each SELECT statement within the MINUS query must have the same number of fields in the result sets with similar data types.

Syntax

The syntax for the MINUS operator in Oracle/PLSQL is:

SELECT expression1, expression2, ... expression_n
FROM tables
[WHERE conditions]
MINUS
SELECT expression1, expression2, ... expression_n
FROM tables
[WHERE conditions];

Parameters or Arguments

expression1, expression2, ... expression_n

The columns or calculations that you wish to retrieve.

tables

The tables that you wish to retrieve records from. There must be at least one table listed in the FROM clause.

WHERE conditions

Optional. The conditions that must be met for the records to be selected.

Note

• There must be same number of expressions in both SELECT statements and have similar data types.

Example - With Single Expression

The following is an Oracle MINUS operator example that returns one field with the same data type:

SELECT supplier_id
FROM suppliers
MINUS
SELECT supplier_id
FROM orders;

This Oracle MINUS example returns all supplier_id values that are in the suppliers table and not in the orders table. What this means is that if a supplier_id value existed in the suppliers table and also existed in the orders table, the supplier_id value would not appear in this result set.

Example - Using ORDER BY

The following is a MINUS operator example that uses an ORDER BY clause:

SELECT supplier_id, supplier_name
FROM suppliers
WHERE state = 'Florida'
MINUS
SELECT company_id, company_name
FROM companies
WHERE company_id <= 400
ORDER BY 2;

In this MINUS example, since the column names are different between the two SELECT statements, it is more advantageous to reference the columns in the ORDER BY clause by their position in the result set. In this example, we've sorted the results by supplier_name / company_name in ascending order, as denoted by the ORDER BY 2.

The supplier_name / company_name fields are in position #2 in the result set.