Selective Operators: Allowing Users to Decide Which Operator to Use

Everyone once in a while you come across something that makes you say, “that is great, now why didn’t I think of that?”. Recently I came across such a thing: an idea of how to make operators in the WHERE clause of a query definable by the user at the moment of report refresh through creative use of SQL and Designer. Honestly I think everyone could benefit from a greater understanding of SQL. This like piece of code is the proof of that:

Selective Operators in Business Objects XI Web Intelligence or Desktop Intelligence at Run-Time


( 'Lesser than or Equal' = @Prompt('Select Operator:','A',{'Lesser than or Equal','Equal','Greater than or Equal'}, MONO,CONSTRAINED) AND Emp.salary <= @Prompt('Enter Salary:','N',,MONO,FREE) ) OR ( 'Equal' = @Variable('Select Operator:') AND Emp.salary = @Variable('Enter Salary:') ) OR ( 'Greater than or Equal' = @Variable('Select Operator:') AND Emp.salary >= @Variable('Enter Salary:') )

The value in this case does not come from fancy Business Object prompt syntax, but rather from creative combinations of SQL and prompts. Note: Please remember this is just an example that you should use to learn the technique and then adapt it to your database’s SQL and to your business requirements.

How it Works

Although this example code has three clauses they can all be bound to each other through their placement in a single universe-level condition, or you could place them in multiple conditions for mixing and matching at the report level. The power of this logic is that it uses one dedicated prompt to collect the desired operator from the user: ‘Lesser than or Equal’,’Equal’, or ‘Greater than or Equal’. Then using hard-coded string values it creates a scenario where only one of the three statements can be true.

And Example with SQL Substitution

In each statement the hard-coded operator text is matched with the actual operator following “Emp.salary”. Therefore, if the user selects “Equal” for the @Prompt(‘Select Operator:’) and “1000” for the @Prompt(‘Enter Salary:’) then the following substitutions will be made for the actual SQL run by Business Objects:

( 'Lesser than or Equal' = 'Equal' AND Emp.salary <= 1000 ) OR ( 'Equal' = 'Equal' AND Emp.salary = 1000 ) OR ( 'Greater than or Equal' = 'Equal' AND Emp.salary >= 1000 )

Because of the magic of SQL and logic only the clause ( 'Equal' = 'Equal' AND Emp.salary = 1000 ) can execute; the others are ignored because the first part of the SQL evaluates to FALSE. In the rules of logic a statement of “FALSE and TRUE” is always FALSE. In this case we don’t know if the second part could evaluate to true, because we don’t know the underlying data, but regardless the entire clause is FALSE when one of the components is FALSE and it is linked to the others using “AND”.

A Few of the Other Details

OK, I feel I got a little technical on the logic, but I think the examples speak clearly enough just in case I lost someone. Again, the whole point that I am making with this code is that it allows users at run time (a.k.a. report refresh) to select the operator for they want to use. If a user wants they can also use the Java Query Panel and change the operators all they want, but they would need access and training to accomplish this.

Some notes: In order to keep it simple I only used the @Prompt statement once and I use @Variable for all of the other instances of the prompt’s use. This helps to avoid problems if I accidentally set the @Prompt differently and it makes it easy to modify Prompt syntax later. The parenthesis around each clause is necessary. Please let us know what you think and share your modifications or spin-offs or alternate uses if you have any.

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6 thoughts on “Selective Operators: Allowing Users to Decide Which Operator to Use

  1. Hi,
    i am not able to see the full list of operators in the query panel. i am using bo xi r3. Is there any specific reason why i am not able to see the operators? please help.

    regards,
    senthil.

  2. Hi senthil, I cannot think of any security setting that would like the list of operators. I would check the single quote characters on your condition created in Designer. Copy and paste of quote characters can get you in trouble when dealing with programming code.

  3. Hi

    This is very cool, thanks
    I just want to know if there is a way to make the Prompts Optional in stead of Mandatory?
    I tried to change the contained to free but it didn’t help

    Thanks

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