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# = (Equals) (Transact-SQL)
[!INCLUDE[tsql-appliesto-ss2008-all_md](../../includes/tsql-appliesto-ss2008-all-md.md)]

  Compares the equality of two expressions (a comparison operator) in [!INCLUDE[ssNoVersion_md](../../includes/ssnoversion-md.md)].  
  
 ![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)  
  
## Syntax  
  
```  
-- Syntax for SQL Server, Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse  
  
expression = expression  
```  
  
## Arguments  
 *expression*  
 Is any valid [expression](../../t-sql/language-elements/expressions-transact-sql.md). If the expressions are not of the same data type, the data type for one expression must be implicitly convertible to the data type of the other. The conversion is based on the rules of [data type precedence](../../t-sql/data-types/data-type-precedence-transact-sql.md).  
  
## Result Types  
 Boolean  
  
## Remarks  
 When you compare two NULL expressions, the result depends on the `ANSI_NULLS` setting:  
  
-   If `ANSI_NULLS` is set to ON, the result is NULL, following the ANSI convention that a NULL (or unknown) value is not equal to another NULL or unknown value.  
  
-   If `ANSI_NULLS` is set to OFF, the result of NULL compared to NULL is TRUE.  

For more information, see [SET ANSI_NULLS (Transact-SQL)](../../t-sql/statements/set-ansi-nulls-transact-sql.md).
  
 Any sort of comparison of a NULL value (an unknown) to a non-NULL value always results in FALSE.  
  
  
## Examples  
  
### A. Using = in a simple query  
 The following example uses the Equals operator to return all rows in the `HumanResources.Department` table in which the value in the `GroupName` column is equal to the word 'Manufacturing'.  
  
```  
-- Uses AdventureWorks  
  
SELECT DepartmentID, Name  
FROM HumanResources.Department  
WHERE GroupName = 'Manufacturing';  
  
```  
  
 [!INCLUDE[ssResult](../../includes/ssresult-md.md)]  
  
```  
  
DepartmentID Name  
------------ --------------------------------------------------  
7            Production  
8            Production Control  
  
(2 row(s) affected)  
  
```  
  
### B. Comparing NULL and non-NULL values  
 The following example uses the Equals (`=`) and Not Equal To (`<>`) comparison operators to make comparisons with `NULL` and nonnull values in a table. The example also shows that `IS NULL` is not affected by the `SET ANSI`_`NULLS` setting.  
  
```  
-- Create table t1 and insert 3 rows.  
CREATE TABLE dbo.t1 (a INT NULL);  
INSERT INTO dbo.t1 VALUES (NULL),(0),(1);  
GO  
  
-- Print message and perform SELECT statements.  
PRINT 'Testing default setting';  
DECLARE @varname int;   
SET @varname = NULL;  
  
SELECT a  
FROM t1   
WHERE a = @varname;  
  
SELECT a   
FROM t1   
WHERE a <> @varname;  
  
SELECT a   
FROM t1   
WHERE a IS NULL;  
GO  
  
-- SET ANSI_NULLS to ON and test.  
PRINT 'Testing ANSI_NULLS ON';  
SET ANSI_NULLS ON;  
GO  
DECLARE @varname int;  
SET @varname = NULL  
  
SELECT a   
FROM t1   
WHERE a = @varname;  
  
SELECT a   
FROM t1   
WHERE a <> @varname;  
  
SELECT a   
FROM t1   
WHERE a IS NULL;  
GO  
  
-- SET ANSI_NULLS to OFF and test.  
PRINT 'Testing SET ANSI_NULLS OFF';  
SET ANSI_NULLS OFF;  
GO  
DECLARE @varname int;  
SET @varname = NULL;  
SELECT a   
FROM t1   
WHERE a = @varname;  
  
SELECT a   
FROM t1   
WHERE a <> @varname;  
  
SELECT a   
FROM t1   
WHERE a IS NULL;  
GO  
  
-- Drop table t1.  
DROP TABLE dbo.t1;  
  
```  
  
 [!INCLUDE[ssResult](../../includes/ssresult-md.md)]  
  
```  
Testing default setting  
a  
-----------  
NULL  
  
(1 row(s) affected)  
  
a  
-----------  
0  
1  
  
(2 row(s) affected)  
  
a  
-----------  
NULL  
  
(1 row(s) affected)  
  
Testing ANSI_NULLS ON  
a  
-----------  
  
(0 row(s) affected)  
  
a  
-----------  
  
(0 row(s) affected)  
  
a  
-----------  
NULL  
  
(1 row(s) affected)  
  
Testing SET ANSI_NULLS OFF  
a  
-----------  
NULL  
  
(1 row(s) affected)  
  
a  
-----------  
0  
1  
  
(2 row(s) affected)  
  
a  
-----------  
NULL  
  
(1 row(s) affected)  
  
```  
  
## See Also  
 [Data Types &#40;Transact-SQL&#41;](../../t-sql/data-types/data-types-transact-sql.md)   
 [Expressions &#40;Transact-SQL&#41;](../../t-sql/language-elements/expressions-transact-sql.md)   
 [Operators &#40;Transact-SQL&#41;](../../t-sql/language-elements/operators-transact-sql.md)