Use an SQL expression to create a formula. See below on how to do this:

• an SQL expression begins and ends with a delimiter ~S~
• a formula can contain any number of SQL expressions
• an SQL expression cannot contain logical conditions ([..:..]..)
• an SQL expression cannot contain temp tables with with #
• an SQL expression can contain variables (# ... #)
• Logical conditions can contain SQL expression.

You can use any mathematical function available in your version of SQL Server when creating an SQL expression. For example:

• SIN( float_expression )
  Returns the trigonometric sine of the given angle (in radians) in an approximate numeric (float) expression,

• COS ( float_expression )
  A mathematic function that returns the trigonometric cosine of the given angle (in radians) in the given expression,

• TAN ( float_expression )
  Returns the tangent of the input expression,

• SQRT ( float_expression )
  Returns the square root of the given expression,

• For all other mathematical functions visit: https://msdn.microsoft.com/en-us/library/ms174077.aspx.
  

Formula including a condition such as for example: [#KOLICINA#>20:#Cena#*0,9] [#KOLICINA#>10:#Cena#*0,95] #Cena#

can be created using the following SQL expression:

~S~
case
  when #KOLICINA# > 20 then #Cena# * 0.9
  when #KOLICINA# > 10 then #Cena# * 0,95
  else #Cena#
end
~S~

or

~S~ dbo.MojaFunkcija(#KOLICINA#, #Cena#) ~S~

In this case it is required that you have a customized function dbo.MojaFunkcija().

You cannot test or validate an SQL expression using Formula builder.