When you create a report expression or a calculation based on a layout expression, unsupported functions do not appear in the Functions tab of the expression editor. Specifically, there is no Summaries folder, and some operators, constants, and constructs are also unavailable. These functions are not available because only the database can perform them. Report expressions and calculations based on layout expressions are performed in Report Studio.
To see the complete list of functions available in the expression editor, except for report functions, create a detail or group calculation. All functions are available when you create a detail or group calculation because these calculations are performed in the database and not in Report Studio.
When IBM Cognos 8 concatenates strings locally and if any of the involved strings contain null values, the result of the concatenation is an empty cell or a null value. This occurs because IBM Cognos 8 requires that an expression that involves a null value returns a null value. Many databases ignore null strings when they perform concatenations. For example, if you concatenate strings A, B, and C, and if string B is a null value, the database may concatenate only strings A and C.