What Is Not Equal in SQL
The SQL Not Equal operator belongs to the group of comparison operators which means it can be used to compare expressions. In this case, an expression is a combination of symbols that has a single data value. It can be variables, constants, columns or scalar functions.
As SQL Not Equal is a binary operator, it cannot be used to compare more than two expressions at once.
Theory is great, but we recommend digging deeper!
Return Values of SQL Not Equal
SQL Not Equal is a boolean operator. That means its return value can be either
True (if one expression in SQL does not equal the other) or
False (if the expressions are equal).
If either of the expressions has a NULL value, the SQL Not Equal will also return
Two Types of Syntax for Not Equal
There are two ways to write the SQL Not Equal operator:
exp <> exp exp != exp
Both of them achieve the same result. However, we recommend you to use the first type of syntax, as it complies with the ISO standard, while the second one does not.