# include <stdio.h>

# include <string.h>

EXEC SQL INCLUDE SQLCA;
 EXEC SQL DECLARE student TABLE /* Graduate student table */
  (sname char(25), /* Name */
   sage integer1, /* Age */
   sbdate char(25), /* Birth date */
   sgpa float4, /* Grade point average */
   sidno integer, /* Unique student number */
   scomment varchar(200), /* General comments */
   sadvisor char(25)); /* Advisor's name */
EXEC SQL DECLARE professor TABLE /* Professor table
*/
  (pname char(25), /* Professor's name */
   pdept char(10)); /* Department */
 
EXEC SQL BEGIN DECLARE SECTION;
  /* Global grad student record maps to database table */
  struct {
    char sname[26];
    short sage;
    char sbdate[26];
    float sgpa;
    int sidno;
    char scomment[201];
    char sadvisor[26];
  } grad;

 
EXEC SQL END DECLARE SECTION;
/*
** Function prototypes for C++ only so that this is compatible
** with old-style C compilers
*/
# ifdef __cplusplus
void Master(void);
 void Load_Students(char *adv);
 int Student_Info_Changed(void);
 # endif /* __cplusplus */
 
/*
** Procedure: MAIN
** Purpose: Start up program and call Master driver.
*/

main()
{
  /* Start up INGRES and the FORMS system */
  EXEC FRS FORMS;
 
  EXEC SQL WHENEVER SQLERROR STOP;
  EXEC FRS MESSAGE 'Initializing Student Administrator . . .';
 
  EXEC SQL CONNECT personnel;
 
  Master();
 
  EXEC FRS CLEAR SCREEN;
  EXEC FRS ENDFORMS;
  EXEC SQL DISCONNECT;
 }
 
 
/*
** Procedure: Master
** Purpose: Drive the application, by running "masterfrm" and
** allowing the user to "zoom" into a selected student.
** Parameters:
** None - Uses the global student "grad" record.
*/

# ifdef __cplusplus
void
Master(void)
# else
Master()
# endif /* __cplusplus */

{
  EXEC SQL BEGIN DECLARE SECTION;
    /* Professor info maps to database table */
    struct {
      char pname[26];
      char pdept[11];
    } prof;
 
    /* Useful forms system information */
    int lastrow, /* Lastrow in table field */
         istable; /* Is a table field? */
 
    /* Local utility buffers */
    char msgbuf[100]; /* Message buffer */
    char respbuf[256]; /* Response buffer */
    char old_advisor[26]; /* Old advisor before ZOOM */

 
    /* Externally compiled master form */
    extern int *masterfrm;
  EXEC SQL END DECLARE SECTION;
 
  EXEC FRS ADDFORM :masterfrm;
 
  /*
  ** Initialize "studenttbl" with a data set in READ mode.
  ** Declare hidden columns for all the extra fields that
  ** the program will display when more information is
  ** requested about a student. Columns "sname" and "sage"
  ** are displayed. All other columns are hidden, to be
  ** used in the student information form.
  */
  EXEC FRS INITTABLE masterfrm studenttbl READ
    (sbdate = char(25),
     sgpa = float4,
     sidno = integer4,
     scomment = char(200),
     sadvisor = char(20));
 
  EXEC FRS DISPLAY masterfrm UPDATE;
 
  EXEC FRS INITIALIZE;
  EXEC FRS BEGIN;
    EXEC FRS MESSAGE 'Enter an Advisor name . . .';
    EXEC FRS SLEEP 2;
  EXEC FRS END;
 
  EXEC FRS ACTIVATE MENUITEM 'Students', FIELD 'pname';
 
  EXEC FRS BEGIN;
 

    /* Load the students of the specified professor */
    EXEC FRS GETFORM (:prof.pname = pname);
 
    /* If no professor name is given, resume */
    if (prof.pname[0] == '\0')
      EXEC FRS RESUME FIELD pname;
 
    /*
    ** Verify that the professor exists. Local error handling
    ** just prints the message and continues. Assume that each
    ** professor has exactly one department.
    */
    EXEC SQL WHENEVER SQLERROR CALL SQLPRINT;
    EXEC SQL WHENEVER NOT FOUND CONTINUE;
    prof.pdept[0] = '\0';
    EXEC SQL SELECT pdept
      INTO :prof.pdept
      FROM professor
      WHERE pname = :prof.pname;
 
    if (prof.pdept[0] == '\0')
    {
      sprintf(msgbuf,
        "No professor with name \"%s\" [RETURN]",
        prof.pname);
      EXEC FRS PROMPT NOECHO (:msgbuf, :respbuf);
      EXEC FRS CLEAR FIELD ALL;
      EXEC FRS RESUME FIELD pname;
    }
 
    /* Fill the department field and load students */
    EXEC FRS PUTFORM (pdept = :prof.pdept);
    EXEC FRS REDISPLAY; /* Refresh for query */
 
    Load_Students(prof.pname);
 
    EXEC FRS RESUME FIELD studenttbl;
 
  EXEC FRS END; /* "Students" */
 
  EXEC FRS ACTIVATE MENUITEM 'Zoom';
  EXEC FRS BEGIN;
 
 
    /*
    ** Confirm that user is in "studenttbl" and that
    ** the table field is not empty. Collect data from
    ** the row and zoom for browsing and updating.
    */
    EXEC FRS INQUIRE_FRS field masterfrm
      (:istable = table);
 
    if (istable == 0)
    {
      EXEC FRS PROMPT NOECHO
        ('Select from the student table [RETURN]',
         :respbuf);
      EXEC FRS RESUME FIELD studenttbl;
    }
 
    EXEC FRS INQUIRE_FRS table masterfrm
      (:lastrow = lastrow);
 
    if (lastrow == 0)
    {
      EXEC FRS PROMPT NOECHO
        ('There are no students [RETURN]',
         :respbuf);
      EXEC FRS RESUME FIELD pname;
    }
 
    /* Collect all data on student into global record
*/
    EXEC FRS GETROW masterfrm studenttbl
        (:grad.sname = sname,
         :grad.sage = sage,
         :grad.sbdate = sbdate,
         :grad.sgpa = sgpa,
         :grad.sidno = sidno,
         :grad.scomment = scomment,
         :grad.sadvisor = sadvisor);
 
    /*
    ** Display "studentfrm," and if any changes were made,
    ** make the updates to the local table field row.
    ** Only make updates to the columns corresponding to
    ** writable fields in "studentfrm". If the student
    ** changed advisors, then delete the row from the display.
    */
    strcpy(old_advisor, grad.sadvisor);
    if (Student_Info_Changed())
    {
      if (strcmp(old_advisor, grad.sadvisor) != 0)
        EXEC FRS DELETEROW masterfrm studenttbl;
      Else
        EXEC FRS PUTROW masterfrm studenttbl
           (sgpa = :grad.sgpa,
           scomment = :grad.scomment,
           sadvisor = :grad.sadvisor);
     }
 
 
  EXEC FRS END; /* "Zoom" */
 
  EXEC FRS ACTIVATE MENUITEM 'Exit';
  EXEC FRS BEGIN;
    EXEC FRS BREAKDISPLAY;
  EXEC FRS END; /* "Exit" */
  EXEC FRS FINALIZE;
 
} /* Master */
 
/*
** Procedure: Load_Students
** Purpose: Given an advisor name, load into the "studenttbl"
** table field all the students who report to the
** professor with that name.
** Parameters:
** advisor - User-specified professor name.
** Uses the global student record.
*/

# ifdef __cplusplus
void
Load_Students(char *adv)
# else
Load_Students(adv)
char *adv;
# endif /* __cplusplus */
{
  EXEC SQL BEGIN DECLARE SECTION;
    char *advisor = adv;
  EXEC SQL END DECLARE SECTION;
 
  EXEC SQL DECLARE studentcsr CURSOR FOR
    SELECT sname, sage, sbdate, sgpa, sidno, scomment, sadvisor
    FROM student
    WHERE sadvisor = :advisor;
 
  /*
  ** Clear previous contents of table field. Load the table
  ** field from the database table based on the advisor name.
  ** Columns "sname" and "sage" will be displayed, and all
  ** others will be hidden.
  */
  EXEC FRS MESSAGE 'Retrieving Student Information . . .';
 
  EXEC FRS CLEAR FIELD studenttbl;
 
  EXEC SQL WHENEVER SQLERROR GOTO Load_End;
  EXEC SQL WHENEVER NOT FOUND GOTO Load_End;
 
  EXEC SQL OPEN studentcsr;
 
 
  /*
  ** Before we start the loop, we know that the OPEN was
  ** successful and that NOT FOUND was not set.
  */
  while (sqlca.sqlcode == 0)
  {
    EXEC SQL FETCH studentcsr INTO :grad;
 
    EXEC FRS LOADTABLE masterfrm studenttbl
        (sname = :grad.sname,
         sage = :grad.sage,
         sbdate = :grad.sbdate,
         sgpa = :grad.sgpa,
         sidno = :grad.sidno,
         scomment = :grad.scomment,
         sadvisor = :grad.sadvisor);
  }
 
Load_End: /* Clean up on an error, and close
cursors */
  EXEC SQL WHENEVER NOT FOUND CONTINUE;
  EXEC SQL WHENEVER SQLERROR CONTINUE;
  EXEC SQL CLOSE studentcsr;
 
} /* Load_Students */
 
/*
** Procedure: Student_Info_Changed
** Purpose: Allow the user to zoom in on the details of a selected
** student. Some of the data can be updated by the user.
** If any updates were made, then reflect these back into
** the database table. The procedure returns TRUE if any
** changes were made.
** Parameters:
** None - Uses data in the global "grad" record.
** Returns:
** TRUE/FALSE - Changes were made to the database.
** Sets the global "grad" record with the new data. */
 
# ifdef __cplusplus
int
Student_Info_Changed(void)
# else
int
Student_Info_Changed()
# endif /* __cplusplus */
 
{
  EXEC SQL BEGIN DECLARE SECTION;
    int changed; /* Changes made to data in form */
    int valid_advisor; /* Valid advisor name? */
    extern int *studentfrm; /* Compiled form */
 
  EXEC SQL END DECLARE SECTION;
 
  /* Control ADDFORM to only initialize once */
  static int loadform = 0;
 
  if (!loadform)
  {
    EXEC FRS MESSAGE 'Loading Student form . . .';
    EXEC FRS ADDFORM :studentfrm;
    loadform = 1; }
 
 
  /* Local error handler just prints error and continues */
  EXEC SQL WHENEVER SQLERROR CALL SQLPRINT;
  EXEC SQL WHENEVER NOT FOUND CONTINUE;
 
  EXEC FRS DISPLAY studentfrm FILL;
  EXEC FRS INITIALIZE
    (sname = :grad.sname,
     sage = :grad.sage,
     sbdate = :grad.sbdate,
     sgpa = :grad.sgpa,
     sidno = :grad.sidno,
     scomment = :grad.scomment,
     sadvisor = :grad.sadvisor);
 
  EXEC FRS ACTIVATE MENUITEM 'Write';
  EXEC FRS BEGIN;
 
    /*
    ** If changes were made, then update the database
    ** table. Only bother with the fields that are not
    ** read-only.
    */
    EXEC FRS INQUIRE_FRS form (:changed = change);
 
    if (changed == 1)
    {
      EXEC FRS VALIDATE;
      EXEC FRS MESSAGE 'Writing changes to database. . .';
 
      EXEC FRS GETFORM
        (:grad.sgpa = sgpa,
         :grad.scomment = scomment,
         :grad.sadvisor = sadvisor);
 
      /* Enforce integrity of professor name */
      valid_advisor = 0;
      EXEC SQL SELECT 1 INTO :valid_advisor
        FROM professor
        WHERE pname = :grad.sadvisor;
 
      if (valid_advisor == 0)
      {
        EXEC FRS MESSAGE 'Not a valid advisor name';
        EXEC FRS SLEEP 2;
        EXEC FRS RESUME FIELD sadvisor;
      }
 
      else
      {
        EXEC SQL UPDATE student SET
          sgpa = :grad.sgpa,
          scomment = :grad.scomment,
          sadvisor = :grad.sadvisor
          WHERE sidno = :grad.sidno;
        EXEC FRS BREAKDISPLAY;
      }
    }
  EXEC FRS END; /* "Write" */
 
 
  EXEC FRS ACTIVATE MENUITEM 'Quit';
  EXEC FRS BEGIN;
    /* Quit without submitting changes */
    changed = 0;
    EXEC FRS BREAKDISPLAY;
  EXEC FRS END; /* "Quit" */
 
  EXEC FRS FINALIZE;
  return (changed == 1);
 } /* Student_Info_Changed *