Declared variable in SELECT statement

[ikim2000]

What does the select statement do below and what does the declared variable do in that statement? I seen it being used with "WHERE" as well. Thx, Ik.
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declare @vID int
select @vID = CustomerID from tblCustomer

 

[Deeba]

Hi,
This is straight out of SQL BOL:

SELECT @local_variable
Specifies that the given local variable (created using DECLARE @local_variable) should be set to the specified expression.

SELECT @local_variable is usually used to return a single value into the variable. It can return multiple values if, for example, expression is the name of a column. If the SELECT statement returns more than one value, the variable is assigned the last value returned.

If the SELECT statement returns no rows, the variable retains its present value. If expression is a scalar subquery that returns no value, the variable is set to NULL.

Hope that answers your question.
~Deeba~

 

[DrewConn]

The select statement assigns the value of CustomerID from the tblCustomer table to the variable vID.