Using comparison operators in SELECT clause of T-SQL query

You should use CASE clause:

CASE
    WHEN FieldA > FieldB THEN 1
    ELSE 0
END AS [BIT]

You can use IIF function. For example:

SELECT IIF(FieldA > FieldB, 1, 0) AS YourBitColumn FROM t

IFF Function's syntax like as below:

IIF( boolean_expression, true_value, false_value )

IFF returns, If boolean_expression is true, then true_value, otherwise false_value

For more information about IFF function : Logical Functions - IIF (Transact-SQL)

Select Convert(Bit, Case When FieldA > FieldB Then 1 Else 0 End) As YourBitColumn

If you want to return a BIT, then you need the convert (or cast) to a bit data type, otherwise, SQL would interpret the hard coded constant (1 or 0) as an integer.