&= (Bitwise AND assignment) (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
SQL analytics endpoint in Microsoft Fabric
Warehouse in Microsoft Fabric
SQL database in Microsoft Fabric
Performs a bitwise logical AND operation between two integer values, and sets a value to the result of the operation.
Transact-SQL syntax conventions
Syntax
expression &= expression
Arguments
expression
Any valid expression of any one of the data types in the numeric category, except the bit data type.
Return types
Returns the data type of the argument with the higher precedence. For more information, see Data type precedence (Transact-SQL).
Remarks
The &= operator is shorthand for using the = and & operators. The following two queries are equivalent.
-- &= operator
DECLARE @bitwise INT = 1;
SET @bitwise &= 1;
SELECT @bitwise;
GO
-- = and & operators
DECLARE @bitwise INT = 1;
SET @bitwise = @bitwise & 1;
SELECT @bitwise;
GO
Both examples return a result of 1.
For more information, see & (Bitwise AND) (Transact-SQL).