!= or for Not Equal in T-SQL: Which Operator Should I Use?

Non-equal operator in T-SQL: Choice of != and <>

When comparing values ​​in Transact-SQL (T-SQL), developers can use two "not equal to" operators: != and <>. While both are efficient at performing the required comparisons, for the sake of code clarity and consistency, it's critical to understand their key differences.

!= and <>: Syntax and standards

The syntax of

!= (pronounced "bang equal") is derived from popular programming languages ​​such as C and JavaScript. It is supported by most relational database management systems (RDBMS).

(pronounced "angle equal") is the ANSI standard operator that means "not equal to". It is supported only in a few RDBMS, such as IBM DB2 and Microsoft Access.

T-SQL preferred syntax

In T-SQL, the preferred "not equal" syntax is !=. Here’s why:

• It is supported by a wider range of databases.
• It is more commonly used in mainstream programming languages.
• It's easier to remember and type.

Database that supports both != and <>

Some RDBMS support both != and <>, allowing developers to flexibly choose syntax. These databases include:

• Apache Derby
• IBM Informix
• Microsoft SQL Server
• MySQL
• Oracle
• PostgreSQL

Only databases that support <>

Some RDBMS strictly adhere to the ANSI standard and only support <> to mean "not equal to". These databases include:

• IBM DB2 UDB
• Microsoft Access

Summary

Although != and <> serve the same purpose in T-SQL, != is the preferred syntax due to its widespread support, familiarity in other programming languages, and ease of use. Developers should be aware of syntax differences when using different RDBMSs and strive for consistency in their own code.

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