%= (Modulus 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
Divides one number by another and sets a value to the result of the operation. For example, if a variable @x equals 38, then @x %= 5 takes the original value of @x, divides by 5, and sets @x to the remainder of that division (3).
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.
Result types
Returns the data type of the argument with the higher precedence. For more information, see Data type precedence (Transact-SQL).
Remarks
For more information, see % (Modulus) (Transact-SQL).