In this exammple, "MyLib" and "MyFile" are the names of RPG variables. This is what the SQL statement will load the results into... these RPG variable names.

"System_Table_Schema" is (believe it or not) the actual field name in the physical file that Rob is reading. SQL can have up to 30 characters in the name of a field in a file.

For some reason, Rob is renaming "System_Table_Schema" as "Library" in his SQL statement. That means that the result of the SELECT statement goes into a "Result Set" (you might think of this as a temporary file, except that it's in memory, not on disk -- and it contains the results of the query -- just a holding place within SQL for the output of the SELECT statement). So in the temporary output from SQL, the field will be renamed from System_Table_Schema to Library. Then this Library field is loaded into the MyLib variable in the RPG program.

I have no clue why Rob renamed the field before loading it into a variable in this particular example.

However, if you ran this statement interactively (instead of inside an RPG program) the column heading would read "Library" instead of "System_Table_Schema" which might be easier for an i5/OS veteran to understand. (Since "Schema" is what libraries are called in SQL verbiage).


David Turnidge wrote:
Thank you for this... I'm trying to learn SQL and have a question...

You define "MyLib" and "MyFile", however you declare C1 selecting
"System_Table_Schema" as "library", and System_Table_Name" as "file", from
qsys2/systables....

Then you open C1. The you Fetch C1 int :MyLib, :MyFile. What is the
relationship between MyLib and System_Table_Schema???

Thank you,

Dave


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