Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
Expressions versus Equations. A difference between expressions and equations is what each represents. An expression shows a math relationship. One key to an expression is that there is no solution. An expression does not have an answer. An expression, however, can be evaluated. To evaluate an expression, substitute values for the variables.
Is a simple expression to which input_expression is compared when the simple CASE format is used. when_expression is any valid expression. The data types of input_expression and each when_expression must be the same or must be an implicit conversion.