String Expression to be evaluated to number

Question

I need to write a TSQL user defined function which will accept a string and return a number.

I will call the function like dbo.EvaluateExpression(\'10*4.5*0.5\

Answer 1

Use this Function, It will absolutely working.

CREATE FUNCTION dbo.EvaluateExpression(@list nvarchar(MAX))

RETURNS Decimal(10,2)
AS

BEGIN
Declare @Result Decimal(10,2)
set @Result=1
 DECLARE @pos        int,
       @nextpos    int,
       @valuelen   int

SELECT @pos = 0, @nextpos = 1


WHILE @nextpos > 0
  BEGIN
     SELECT @nextpos = charindex('*', @list, @pos + 1)
     SELECT @valuelen = CASE WHEN @nextpos > 0
                             THEN @nextpos
                             ELSE len(@list) + 1
                        END - @pos - 1

                        Set @Result=@Result*convert(decimal(10,2),substring(@list, @pos + 1, @valuelen))


     SELECT @pos = @nextpos
  END

RETURN @Result
END

You Can use this

Select 10* dbo.EvaluateExpression('10*4.5*0.5')