What Is an Expression in SQL Server Transact-SQL?

An expression is a combination of identifiers, values, and operators that SQL Server 2005 can evaluate to obtain a numeric value.

A simple expression could be a constant, a function, a column name, a variable, or a subquery without any operators.

Complex expressions can be constructed by joining other expressions with operators.

The following tutorial exercise shows you some expression examples:

DECLARE @site VARCHAR(40);
SET @site = 'FYIcenter.com';
SELECT 'Welcome'; -- Expression: constant
SELECT @site; -- Expression: variable
SELECT GETDATE(); -- Expression: function
SELECT 'Welcome to '+@site; -- Expression with an operator
GO
Welcome
FYIcenter.com
2007-05-19 18:42:09.077
Welcome to FYIcenter.com

DECLARE @rate NUMERIC(5,2);
DECLARE @deposit MONEY;
DECLARE @value MONEY;
SET @rate = 5.25;
SET @deposit = 4000.00;

-- Expression with multiple operators.
SET @value = @deposit*(1.0+@rate/100)*(1.0+@rate/100);
PRINT @value;
GO
4431.03

⇒Numeric Expressions and Functions in SQL Server Transact-SQL

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