The CL Corner: Enhancing WRKQRY Reports the Easy Way

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Let's look more uses of the RUNSQL CL command.

 

I recently received a note asking if there was a way to add the day of week to query reports generated by the IBM Query for i (5770-QU1) product. That is, take a current report containing dates as shown below:

PROJECT     TASK        CONTACT     TSKSTRDAT   TSKENDDAT    

ABC         Some task   JDOE        2015-03-09  2015-04-01   

ABC         Diff task   JSMITH      2015-03-24  2015-04-10   

ABC         Testing     QAMGR       2015-04-02  2015-05-28               

And start showing the day of week as in the following:

PROJECT     TASK        CONTACT     TSKSTRDAT   TSKSTRDOW   TSKENDDAT   TSKENDDOW

ABC         Some task   JDOE        2015-03-09  Monday      2015-04-01  Wednesday

ABC         Diff task   JSMITH      2015-03-24  Tuesday     2015-04-10  Friday   

ABC         Testing     QAMGR       2015-04-02  Thursday    2015-05-28  Thursday 

This can certainly be done using the query product and a non-trivial set of result fields, but it's…well…ugly. My preference is to have the database of the IBM i determine the day of week and then provide it to the query product. This article goes over one way to accomplish this.

For background, let's assume we have a physical file on the system, named PROJECTS, with the following DDS definition:

A          R PROJRCD            

A            PROJECT       10A  

A            TASK          10A  

A            CONTACT       10A  

A            TSKSTRDAT       L  

A            TSKENDDAT       L  

A          K PROJECT  

The fields being defined are:

  1. ProjectA 10-character alphanumeric value representing a project that is being tracked
  2. TaskA 10-character alphanumeric value representing a task within a project
  3. ContactA 10-character alphanumeric value representing a user ID identifying a contact for the task
  4. TskStrDatA date value representing the starting date of a task within a project
  5. TskEndDatA date value representing the ending date of a task within a project

PROJECTS might have been created using the Create Physical File (CRTPF) command:

CRTPF FILE(BVINING/PROJECTS) SRCFILE(BVINING/QDDSSRC) 

To create the first report shown, the PROJECTS file would have three records, which might have been entered using an application program, a utility such as DFU, or (for our purposes) the following three RUNSQL CL commands.

RUNSQL SQL('INSERT INTO BVINING/PROJECTS

VALUES(''ABC'', ''Some task'', ''JDOE'', ''2015-03-09'', ''2015-04-01'')')

COMMIT(*NONE)  

RUNSQL SQL('INSERT INTO BVINING/PROJECTS

VALUES(''ABC'', ''Diff task'', ''JSMITH'', ''2015-03-24'', ''2015-04-10'')')

COMMIT(*NONE)  

RUNSQL SQL('INSERT INTO BVINING/PROJECTS

VALUES(''ABC'', ''Testing'', ''QAMGR'', ''2015-04-02'', ''2015-05-28'')')

COMMIT(*NONE)  

If you're not familiar with the Run SQL (RUNSQL) command, it's a CL command that allows you to run most SQL statements from either a command line or a CL program. Previous articles introducing the command include Introducing the New Run SQL Command, Using the SQL Select Statement with RUNSQL, and More on the RUNSQL CL Command.

To have the i database determine the day of week for the task start date (TskStrDat) and the task end date (TskEndDat), we'll create a view of the database that adds two fields: task start day of week (TskStrDoW) and task end day of week (TskEndDoW). The following CL program, named PROJVIEW, will create this view, which will also be named PROJVIEW in library BVINING.

Pgm                                                               

                                                                  

RunSQL    SQL('Create View BVINING/ProjView +                     

                  (Project, Task, Contact, +                      

                   TskStrDat, TskStrDoW, +                        

                   TskEndDat, TskEndDoW) +                        

                as Select +                                       

                     Project, Task, Contact, +                    

                     TskStrDat, Varchar(DayName(TskStrDat), 10), +   

                     TskEndDat, Varchar(DayName(TskEndDat), 10) +    

                    from BVINING/Projects') +                     

          Commit(*None)                                           

                                                                  

EndPgm                                                            

The RunSQL command is running an SQL Create View statement. The seven field names listed within parentheses represent the fields defined within the view. The Select clause identifies where the values associated with the seven fields defined within the view come from, with Project, Task, Contact, TskStrDat, and TskEndDat simply being the values found in the physical file BVINING/PROJECTS. The values for the two new fields that are defined within the view, TskStrDoW and TskEndDoW, are defined as coming from Varchar(DayName(TskStrDat), 10) and Varchar(DayName(TskEndDat), 10), respectively.

DayName is an SQL function that returns a mixed-case character string containing the name of the day (for example, Friday, though the actual value returned will depend on the National Language Version in use by your job) associated with the parameter passed to it. The parameter can be a constant or a variable of the type date, timestamp, character, or graphic. In our case, we're using the date fields of the PROJECTS physical file. The character string returned is defined as being a variable-length string of up to 100 characters. Query, when displaying or printing this string, will allocate the full 100 characters, which is probably not what we want.

Varchar is an SQL function that returns a character string associated with the parameter passed to it. The parameter can be integer, decimal, floating point, character, graphic, date, time, or timestamp. In our case, we're passing it the variable-length string returned by the DayName function. The Varchar function also supports optional parameters, with the first optional parameter allowing us to specify the length of the string we want returned. The value we're using for this optional parameter is 10, indicating that the view should truncate the output of DayName to only the first 10 characters.

To create the PROJVIEW CL program into library BVINING and then run it, you can use the following two commands.

CRTBNDCL PGM(BVINING/PROJVIEW) SRCFILE(BVINING/QCLSRC)

CALL PGM(BVINING/PROJVIEW)

To test the PROJVIEW view, we need to go into the current query definition and make two changes:

  1. Using the "Specify file selections" option, specify that the file to be used is now PROJVIEW.
  2. Using the "Select and sequence fields" option, specify that the fields TskStrDow and TskEndDow are to be included in the query output following TskStrDat and TskEndDat, respectively.

That's it! Use F5 to run the query, and you should now get something like this:

PROJECT     TASK        CONTACT     TSKSTRDAT   TSKSTRDOW   TSKENDDAT   TSKENDDOW

ABC         Some task   JDOE        2015-03-09  Monday      2015-04-01  Wednesday

ABC         Diff task   JSMITH      2015-03-24  Tuesday     2015-04-10  Friday   

ABC         Testing     QAMGR       2015-04-02  Thursday    2015-05-28  Thursday 

While the RunSQL command is running a SQL statement creating the view BVINING/PROJVIEW, you'll notice if you run a Display File Description (DSPFD) command using BVINING/PROJVIEW that the command shows that it's an externally described logical file with an SQL type of view. Likewise, the Display File Field Description (DSPFFD) command shows that PROJVIEW is a logical file with seven fields defined. As long as you declare (DCLF) PROJVIEW within a CL program with Allow variable-length fields (ALWVARLEN) *YES, you'll find you can use it within a CL program in the same way you would any other file.

In the case of the PROJECTS file, per the original email I received, there will always be "real" dates for TskStrDat and TskEndDat, so our initial task is done. Some databases, however, may have associated special meanings to specific datesfor example, I find that January 1 of year 0001 is commonly used to indicate that there is no known date (at least at this time). The PROJVIEW view will handle this just fine, and you'll find out quickly enough that the date 0001-01-01 is considered to be a Monday. But do you really want all of these spurious Mondays to show up in the output?

The previous Create View statement barely touches what can be done in a view, with the following changed RunSQL command showing a bit more of what's possible.

RunSQL    SQL('Create View BVINING/ProjView +                          

                  (Project, Task, Contact, +                           

                   TskStrDat, TskStrDoW, +                             

                   TskEndDat, TskEndDoW) +                             

                as Select +                                            

                     Project, Task, Contact, +                         

                     TskStrDat, +                                      

                     case when TskStrDat = ''0001-01-01'' then '' '' + 

                          else Varchar(DayName(TskStrDat), 10)  +         

                          end, +                                       

                     TskEndDat, +                                      

                     case when TskEndDat = ''0001-01-01'' then NULL + 

                          else Varchar(DayName(TskEndDat), 10) +         

                          end +                                       

                    from BVINING/Projects') +                        

          Commit(*None)                                

Rather than simply using the Varchar and DayName SQL functions, we're now also using the SQL Case expression to enable different processing based on the evaluation of one of more conditions.

The elements of the Case expression, while using different terminology, are essentially those of a CL Select control structure where Case is the equivalent of Select, When is When, Else is Otherwise, and End is EndSelect. So what we're doing with the first Case expression in the new PROJVIEW is checking whether the value of TskStrDat is January 1, 0001 and, if so, setting TskStrDow to blanks. If TskStrDat is not 1/1/0001, we're then using the same Varchar(DayName(TskStrDat), 10) solution as before. To demonstrate some flexibility in how we want to handle dates, we're processing TskEndDat in a slightly different manner. If TskEndDat is 1/1/0001, we're setting TskEndDow to the NULL value, otherwise to the name of the day.

As the previous query output would have included dates of 1/1/0001, we'll simply continue to show those values (though we don't have to if we don't want to).

To test this change to PROJVIEW, let's update two of our PROJECTS date values to January 1, 0001, with the following two RUNSQL commands.

RUNSQL SQL('Update Projects set TskStrDat = ''0001-01-01''

where Project = ''ABC'' and Task = ''Diff task''') COMMIT(*NONE)                       

                                                         

RUNSQL SQL('Update Projects set TskEndDat = ''0001-01-01''

where Project = ''ABC'' and Task = ''Testing''') COMMIT(*NONE)   

Delete the previous PROJVIEW view with this:

RunSQL    SQL('Drop View BVINING/ProjView') Commit(*None)  

Then recompile and call the updated PROJVIEW CL program.

CRTBNDCL PGM(BVINING/PROJVIEW) SRCFILE(BVINING/QCLSRC)

CALL PGM(BVINING/PROJVIEW)

Running the previous query over the PROJVIEW view now results in output similar to this:

PROJECT     TASK        CONTACT     TSKSTRDAT   TSKSTRDOW   TSKENDDAT   TSKENDDOW

ABC         Some task   JDOE        2015-03-09  Monday      2015-04-01  Wednesday

ABC         Diff task   JSMITH      0001-01-01              2015-04-10  Friday   

ABC         Testing     QAMGR       2015-04-02  Thursday    0001-01-01  -        

This output shows blanks for the starting day of week for task "Diff task" and a dash (reflecting a NULL value) for the ending day of week for task "Testing"and without having touched the query definition.

As mentioned before, you can process this view not just with the query product but also in a CL program. Note, though, that due to the introduction of NULL values for TskEndDow, you'll also need to specify Allow field value of null (ALWNULL) *YES on the CL Declare File (DCLF) command.

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