SQL Server FAQ - What Are Comparison Operations

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What Are Comparison Operations?

Comparison operations return Boolean values by comparing the relative positions of two operands. SQL server supports the following comparison operations:

= (Equal To): Returns Boolean true, if two operands are equal in value.
> (Greater Than): Returns Boolean true, if the left operand has a value greater than the right operand.
< (Less Than): Returns Boolean true, if the left operand has a value less than the right operand.
>= (Greater Than or Equal To): Returns Boolean true, if the left operand has a value greater than or equal to the right operand.
<= (Less Than or Equal To): Returns Boolean true, if the left operand has a value less than or equal to the right operand.
<> (Not Equal To): Returns Boolean true, if two operands are not equal in value.

There are several rules you need to remember about comparison operations:

Comparison operations can be performed on all data types: exact numbers, approximate numbers, character strings, and binary strings.
If two operands have different data types, the operand with a lower data type rank will be implicitly converted to the data type of the other operand.
Character string comparison will be performed based the rules defined in the associated collation.

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