&= (Bitwise AND EQUALS) (Transact-SQL)
Performs a bitwise logical AND operation between two integer values, and sets a value to the result of the operation.
expression &= expression
Is any valid expression of any one of the data types in the numeric category except the bit data type.
Returns the data type of the argument with the higher precedence. For more information, see Data Type Precedence (Transact-SQL).
For more information, see & (Bitwise AND) (Transact-SQL).