Not Equal to in SQL
Updated on 04th Jan, 24 9.1K Views

Through this blog, we will help you understand the concept of Not Equal to in SQL, along with its various examples that can be applied to numbers, strings, dates, and more. We will also discuss the key differences between <> and != operators and their applications in the real world.

Table of Content

We do have a full informative video to get the idea of the complete knowledge of the topic:

What is Not Equal to Operator in SQL?

The “Not Equal to” operator (<> or !=) in SQL is a comparison operator used to check whether two expressions are unequal. It’s commonly used in SQL queries to filter data by omitting rows where certain conditions are met, specifically where the values in two expressions are not the same.

  • When the expressions are not equal: The operator returns True. For example, in the comparison 99 <> 100, the expressions are not equal (99 is not equal to 100), so the result of this comparison is True.
  • When the expressions are equal: The operator returns False. For instance, in the comparison 100 <> 100, the expressions are equal (100 is equal to 100), so the result of this comparison is False.

If we talk about the syntax, Not Equal to in SQL is commonly used with the Where clause so that we can do the proper comparison with the records. This Not Equal to Operator is also called an inequality operator.
In case you are wondering which of these to use, both will produce the same results.

Syntax:

WHERE expression1 <> expression2
  • Expression 1 and Expression 2 can be any text, number, constant value, or column value 
  • The default string comparison in SQL is case-insensitive, which means the expression ‘INTELLIPAAT'<>’intellipaat’ will be false as output.
  • If expression 1 and expression 2 are two different data types, such as strings and numbers, then they are internally type casted for comparison. For example, ‘1’<>1 will be evaluated as false.

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Examples of SQL Not Equal Operator

Now let us take a look at some of the important examples of SQL Not Equal Operators that will provide you with in-depth information about the comparison operator. Here is the respective table named Overall Product that will be used for the following examples:

Overall Product

product_idproduct_namepricecategorysale_date
1Laptop40,000Electronics2023-01-02
2Book10,000Books2023-01-03
3Mobile15,000Electronics2023-01-05

1. Not Equal with Numbers

In this example, we will choose products whose price is not equal to 10,000. Let’s begin by writing the SQL code for it:

SELECT product_name FROM Overall Product
WHERE price <> 10,000;

Output:

product_name
Laptop
Mobile

2. Not Equal with Dates

This is another example where we will make use of the date for the Not Equal comparison to update the records in the table. So here you have to get the product name where sale_date is not equal to 2023-01-02.

SELECT product_name FROM Overall Product
WHERE sale_date <> ‘2023-01-02’;

Output:

product_name
Book
Mobile

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3. Not Equal with Strings

This is the third example where we will be using Not Equal to Operator with a string. In this case, a string is not equal to Electronics:

SELECT product_name FROM Overall Product
WHERE category <> ‘Electronics’

Output:

product_name
Book

4. SQL Not operator and SQL Group By clause

SQL Not Equal to Operator can be utilized by using the GROUP BY clause in the following manner: 

Suppose we have to group the category with respect to their product.

SELECT category, COUNT(*) AS product_count
FROM Overall Product
GROUP BY category;

Output:

Categoryproduct_count
Electronics 2
Books 1

5. Combining Conditions with Not Equal Operators

This is the fifth example where we are going to combine the conditions by using the not-equal comparison operator. Suppose you select a price that is not equal to 40,000 and a category that is not equal to electronics. Here is the basic code in SQL for this specific query.

SELECT * FROM Overall Product
WHERE price <> 40,000 AND category <> Electronics

Output:

product_idproduct_namepricecategorysale_date
2Book10,000Books2023-01-03
3Mobile15,000Electronics2023-01-05

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Difference Between SQL Not Equal Operator <> and !=

Here is a tabular comparison of  <> and != to have a clear view of it:

<> !=
<> is part of the SQL standard.!= is not part of the official SQL standard.
<> can be used freely in SQL statements and is recognized by most database systems.!= might not be recognized by all database systems.
<> adheres to the ISO standard for SQL.!= is not compliant with the ISO standard for SQL.

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Applications of Not Equal to Operator in SQL

Now’s the right time to know the various real-life applications of Not Equal to Operator in the domain of SQL:

  • The “Not Equal to” operator is useful for data validation, ensuring that certain conditions are met or not met before data is inserted or updated.
  • It can be used in join conditions to retrieve rows where the values in the joined columns are not equal.
  • You can use the “Not Equal to” operator to compare the values of two different columns in a table.
  • The “Not Equal to” operator is often used to filter out rows where a particular column has a NULL value. This is useful when you want to retrieve only non-null values.

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Conclusion

With the ongoing advancements in database technologies, there may be improvements in query optimization techniques, making queries involving the “Not Equal to” operator more efficient. As businesses continue to handle large volumes of data, SQL and its operators, including “Not Equal to,” will remain essential for effective data manipulation and analysis.

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FAQs

Is <> and != the same in SQL?

Yes, in most database systems, <> and != are functionally equivalent and can be used interchangeably as the “not equal” operators in SQL.

How to use not equal in SQL?

To use the “not equal” operator in SQL, you can include either <> or != in your WHERE clause to filter rows based on a condition where a column value is not equal to a specified value.

What is not equal in the SQL case?

In SQL, “not equal” is expressed using the <> or != operators. It is used in conditional statements to filter rows where a particular column’s value does not match a specified value.

How do you write not equal to null in SQL?

To check for values that are not equal to NULL in SQL, you can use the “IS NOT NULL” condition in the WHERE clause.

Can you use == in SQL?

No, in SQL, the equality operator is = rather than ==. Therefore, you should use = for equality comparisons in SQL.

What is AND NOT in SQL?

In SQL, “AND NOT” is a logical operator used to combine conditions in a WHERE clause. It retrieves rows that satisfy the first condition and do not satisfy the second condition.

What is the symbol for not equal?

The symbol for “not equal” in SQL is <>. However, some database systems also accept != as an alternative.

What is the not equal operator?

The “not equal” operator in SQL is used to compare values for inequality. It is represented by the symbols <> or !=.

How to remove duplicates in SQL?

To remove duplicates in SQL, you can use the DISTINCT keyword in your SELECT statement.

Is NULL in MS SQL?

In MS SQL, NULL is a special marker used to indicate that a data value does not exist in the database. It is not the same as an empty string or a  zero. To check for NULL values, you can use the “IS NULL” or “IS NOT NULL” conditions in the WHERE clause.

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