Sets a local variable to the value of an expression.
For assigning variables, we recommend that you use [SET @local_variable](../../t-sql/language-elements/set-local-variable-transact-sql.md) instead of SELECT @*local_variable*.
Transact-SQL Syntax Conventions
SELECT { @local_variable { = | += | -= | *= | /= | %= | &= | ^= | |= } expression }
[ ,...n ] [ ; ]
@*local_variable*
Is a declared variable for which a value is to be assigned.
{= | += | -= | *= | /= | %= | &= | ^= | |= }
Assign the value on the right to the variable on the left.
Compound assignment operator:
|operator |action |
|—–|—–|
| = | Assigns the expression that follows, to the variable. |
| += | Add and assign |
| -= | Subtract and assign |
| *= | Multiply and assign |
| /= | Divide and assign |
| %= | Modulo and assign |
| &= | Bitwise AND and assign |
| ^= | Bitwise XOR and assign |
| |= | Bitwise OR and assign |
expression
Is any valid expression. This includes a scalar subquery.
SELECT @*local_variable* is typically used to return a single value into the variable. However, when expression is the name of a column, it can return multiple values. If the SELECT statement returns more than one value, the variable is assigned the last value that is 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.
One SELECT statement can initialize multiple local variables.
[!NOTE]
A SELECT statement that contains a variable assignment cannot be used to also perform typical result set retrieval operations.
In the following example, the variable @var1
is assigned Generic Name
as its value. The query against the Store
table returns no rows because the value specified for CustomerID
does not exist in the table. The variable retains the Generic Name
value.
-- Uses AdventureWorks
DECLARE @var1 varchar(30);
SELECT @var1 = 'Generic Name';
SELECT @var1 = Name
FROM Sales.Store
WHERE CustomerID = 1000 ;
SELECT @var1 AS 'Company Name';
Here is the result set.
Company Name
------------------------------
Generic Name
In the following example, a subquery is used to assign a value to @var1
. Because the value requested for CustomerID
does not exist, the subquery returns no value and the variable is set to NULL
.
-- Uses AdventureWorks
DECLARE @var1 varchar(30)
SELECT @var1 = 'Generic Name'
SELECT @var1 = (SELECT Name
FROM Sales.Store
WHERE CustomerID = 1000)
SELECT @var1 AS 'Company Name' ;
Here is the result set.
Company Name
----------------------------
NULL
[DECLARE @local_variable (Transact-SQL)](../../t-sql/language-elements/declare-local-variable-transact-sql.md)
Expressions (Transact-SQL)
Compound Operators (Transact-SQL)
SELECT (Transact-SQL)