MySQL - Unary Minus Operator (-)

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The Unary Minus operator (-) is a type of Arithmetic Operator supported by MySQL. This operator is just used to change the sign of a value in a database table. In other words, whenever this operator is used, the positive values in a database tables are changed to negative values, and vice versa.

Example

The following query will return -3354, which is the negation of postive number 3354 −

SELECT -3354 as Result;

Output

This will produce the following result −

Result
-3354

Example

This below query will return the output as -5788.687, which is the negation of postive float number 5788.687 −

SELECT -5788.687 as Result;

Output

This will produce the following result −

Result
-5788.687

Example

This query will return 7. The first unary minus negates the negative number (-7), changing it to positive −

SELECT -(-263) as Result;

Output

This will produce the following result −

Result
263

Example

Let us see an example where we change the signs of values in a database table column. First, we create a table named CUSTOMERS using the below query −

CREATE TABLE CUSTOMERS (
   ID INT AUTO_INCREMENT,
   NAME VARCHAR(20) NOT NULL,
   AGE INT NOT NULL,
   ADDRESS CHAR (25),
   SALARY DECIMAL (18, 2),
   PRIMARY KEY (ID)
);

The following query inserts 7 records into the above created table −

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY) VALUES 
(1, 'Ramesh', 32, 'Ahmedabad', 2000.00 ),
(2, 'Khilan', 25, 'Delhi', 1500.00 ),
(3, 'Kaushik', 23, 'Kota', 2000.00 ),
(4, 'Chaitali', 25, 'Mumbai', 6500.00 ),
(5, 'Hardik', 27, 'Bhopal', 8500.00 ),
(6, 'Komal', 22, 'Hyderabad', 4500.00 ),
(7, 'Muffy', 24, 'Indore', 10000.00 );

Execute the following query fetch all the inserted records in the CUSTOMERS table −

Select * From CUSTOMERS;

Following is the CUSTOMERS table −

ID	NAME	AGE	ADDRESS	SALARY
1	Ramesh	32	Ahmedabad	2000.00
2	Khilan	25	Delhi	1500.00
3	Kaushik	23	Kota	2000.00
4	Chaitali	25	Mumbai	6500.00
5	Hardik	27	Bhopal	8500.00
6	Komal	22	Hyderabad	4500.00
7	Muffy	24	Indore	10000.00

Now, using the unary minus (-) operator, let us negate the salaries of every customer −

SELECT ID, NAME, SALARY, -SALARY as 'Negative SALARIES' 
FROM CUSTOMERS;

This will produce the following result −

ID	NAME	SALARY	Negative SALARIES
1	Ramesh	2000.00	-2000.00
2	Khilan	1500.00	-1500.00
3	Kaushik	2000.00	-2000.00
4	Chaitali	6500.00	-6500.00
5	Hardik	8500.00	-8500.00
6	Komal	4500.00	-4500.00
7	Muffy	10000.00	-10000.00