MySQL Not Equal Operator

MySQL Not Equal Operator

The MySQL != or <> operator is used to compare two values. This operator is essential for filtering records where one value is not equal to another.

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Syntax

SELECT column1, column2, ...
FROM table_name
WHERE column1 != value;

SELECT column1, column2, ...
FROM table_name
WHERE column1 <> value;

The != and <> operators have the following components:

• column1, column2, ...: The columns to be retrieved.
• table_name: The name of the table from which to retrieve the data.
• column1 != value or column1 <> value: The condition to filter the records, where column1 is not equal to a specified value.

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Example MySQL Not Equal Operator

Let's look at some examples of the MySQL != and <> operators:

Step 1: Using the Database

USE mydatabase;

This query sets the context to the database named mydatabase.

Step 2: Creating a Table

Create a table to work with:

CREATE TABLE employees (
    id INT AUTO_INCREMENT PRIMARY KEY,
    first_name VARCHAR(50) NOT NULL,
    last_name VARCHAR(50) NOT NULL,
    department VARCHAR(50),
    salary DECIMAL(10, 2)
);

This query creates a table named employees with columns for id, first_name, last_name, department, and salary.

Step 3: Inserting Initial Rows

Insert some initial rows into the table:

INSERT INTO employees (first_name, last_name, department, salary)
VALUES ('John', 'Doe', 'HR', 50000.00),
       ('Jane', 'Smith', 'IT', 60000.00),
       ('Jim', 'Brown', 'IT', 55000.00),
       ('Jake', 'White', 'HR', 52000.00),
       ('Jill', 'Green', 'Marketing', 45000.00);

This query inserts five rows into the employees table.

Step 4: Using Not Equal Operator with WHERE Clause

Use the != operator to filter records based on a condition:

SELECT * 
FROM employees 
WHERE department != 'IT';

This query retrieves all columns from the employees table where the department is not equal to 'IT'.

Step 5: Using Not Equal Operator with Multiple Conditions

Use the != operator with multiple conditions:

SELECT * 
FROM employees 
WHERE department != 'HR' AND salary != 50000.00;

This query retrieves all columns from the employees table where the department is not 'HR' and the salary is not 50000.00.

Step 6: Using Not Equal with Multiple Columns

Use the != operator with multiple columns:

SELECT first_name, last_name 
FROM employees 
WHERE department != 'Marketing' AND salary != 45000.00;

This query retrieves the first_name and last_name columns from the employees table where the department is not 'Marketing' and the salary is not 45000.00.

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Conclusion

The MySQL != and <> operators are powerful tools for filtering records based on a comparison condition. Understanding how to use the != and <> operators is essential for effective data querying and analysis in MySQL.