SQLRPGLE

RPG IV with Embedded SQL

Introduction to RPG IV with Embedded SQL

SQL is a powerful tool in any programmer's skill set. It is possible to leverage this tool from within RPG (& other languages). The source member type for these programs is SQLRPGLE. Here is an example of an embedded SQL statement in non-free RPG:

     C/EXEC SQL
     C+ SELECT * FROM mylib/myfile
     C/END-EXEC

And again in V5r4+ free-form RPG:

     exec sql select * from mylib/myfile;

SQL Directives

Directive	Function performed
SELECT	The Select directive is used to extract data from a Physical file or Table
DECLARE	The Declare Cursor directive is used to define a data path in your program
OPEN	The Open Cursor directive is used to open a data path defined by a Declare Cursor directive.
CLOSE	The Close Cursor directive is used to close a data path opened by a Open cursor directive
FETCH	The Fetch directive is used to extract records from a data path opened via the Open Cursor directive
PREPARE	The Prepare directive is used to prepare an dynamic SQL statement for execution
EXECUTE	The Execute directive is used to execute an dynamic SQL statement prepared via the Prepare directive
EXECUTE IMMEDIATE	The Execute Immediate directive is used to execute an SQL statement directly & does not require a Prepare directive
DELETE	The Delete directive is used to delete data from a Physical file or Table
DROP TABLE	The Drop Table directive is used to delete a Physical file or Table
CREATE TABLE	The Create Table directive is used to create a Physical file or Table
ALTER TABLE	The Alter Table directive is used to change file & field attributes in a Physical file or Table
UPDATE	The Update directive is used to update data from a Physical file or Table

Sample Embedded SQL program

     H ActGrp(*CALLER)
     H DftActGrp(*NO)

     D OpenCursor      PR              n
     D FetchCursor     PR              n
     D CloseCursor     PR              n

     D MyLib           s             10a
     D MyFile          s             10a

      /free
       *inlr=*on;
       if not OpenCursor();
         // perform error routine to alert the troops
         // ...
       Else;
         Dow FetchCursor();
           // putting the fetchcursor on the do loop allows the user of
           // iter, and thus iter will not perform an infinite loop
           // normal processing here...
         EndDo;
         CloseCursor();
       EndIf;
       return;
      /end-free

     P OpenCursor      B
     D OpenCursor      PI                  like(ReturnVar)
     D ReturnVar       s               n

       // The immediately following /EXEC SQL is SQL's version of RPG's H Spec
       // It is never executed.  Just used at compile time.
     C/EXEC SQL
     C+ Set Option
     C+     Naming    = *Sys,
     C+     Commit    = *None,
     C+     UsrPrf    = *User,
     C+     DynUsrPrf = *User,
     C+     Datfmt    = *iso,
     C+     CloSqlCsr = *EndMod
     C/END-EXEC

     C/EXEC SQL
     C+ Declare C1 cursor for
     C+  Select System_Table_Schema as library,
     C+         System_Table_Name   as file
     C+  from qsys2/systables
     C/END-EXEC

     C/EXEC SQL
     C+ Open C1
     C/END-EXEC

      /free
       Select;
         When SqlStt='00000';
           return *on;
         Other;
           return *off;
       EndSl;
      /end-free
     P OpenCursor      E

      /eject
     P FetchCursor     B
     D FetchCursor     PI                  like(ReturnVar)
     D ReturnVar       s               n
     C/EXEC SQL
     C+ Fetch C1 into :MyLib, :MyFile
     C/END-EXEC
      /free
       Select;
         When sqlstt='00000';
           // row was received, normal
           ReturnVar=*on;
         When sqlstt='02000';
           // same as %eof, sooner or later this is normal
           ReturnVar=*off;
         Other;
           // alert the troops!
           ReturnVar=*off;
       EndSl;
       return ReturnVar;
      /end-free
     P FetchCursor     E

      /eject
     P CloseCursor     B
     D CloseCursor     PI                  like(ReturnVar)
     D ReturnVar       s               n
     C/EXEC SQL
     C+ Close C1
     C/END-EXEC
      /free
       Select;
         When sqlstt='00000';
           // cursor was closed, normal
           ReturnVar=*on;
         Other;
           // alert the troops!
           ReturnVar=*off;
       EndSl;
       return ReturnVar;
      /end-free
     P CloseCursor     E