/****************************************************************************
** (c) Copyright IBM Corp. 2007 All rights reserved.
**
** The following sample of source code ("Sample") is owned by International
** Business Machines Corporation or one of its subsidiaries ("IBM") and is
** copyrighted and licensed, not sold. You may use, copy, modify, and
** distribute the Sample in any form without payment to IBM, for the purpose of
** assisting you in the development of your applications.
**
** The Sample code is provided to you on an "AS IS" basis, without warranty of
** any kind. IBM HEREBY EXPRESSLY DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR
** IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Some jurisdictions do
** not allow for the exclusion or limitation of implied warranties, so the above
** limitations or exclusions may not apply to you. IBM shall not be liable for
** any damages you suffer as a result of using, copying, modifying or
** distributing the Sample, even if IBM has been advised of the possibility of
** such damages.
*****************************************************************************
**
** SOURCE FILE NAME: tbintrig.sqC
**
** SAMPLE: How to use an 'INSTEAD OF' trigger on a view
**
**
** SQL STATEMENTS USED:
** DECLARE CURSOR
** SELECT
** OPEN
** FETCH
** CLOSE
** CREATE TABLE
** EXECUTE IMMEDIATE
** PREPARE
** DROP
** CREATE TRIGGER
** INSERT
** DELETE
** UPDATE
**
**
*****************************************************************************
**
** For more information on the sample programs, see the README file.
**
** For information on developing embedded SQL applications see the Developing Embedded SQL Applications book.
**
** For information on using SQL statements, see the SQL Reference.
**
** For the latest information on programming, building, and running DB2
** applications, visit the DB2 Information Center:
** http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp
****************************************************************************/
#include <string.h>
#include <sqlenv.h>
#include <sqlutil.h>
#include "utilemb.h"
#if ((__cplusplus >= 199711L) && !defined DB2HP && !defined DB2AIX) || \
(DB2LINUX && (__LP64__ || (__GNUC__ >= 3)) )
#include <iomanip>
#include <iostream>
using namespace std;
#else
#include <iomanip.h>
#include <iostream.h>
#endif
EXEC SQL BEGIN DECLARE SECTION;
short id;
char name[10];
short dept;
char job[10];
short jobInd;
short years;
short yearsInd;
double salary;
double comm;
short commInd;
char strStmt[1024];
char personsname[20];
sqlint32 ssn;
char company[20];
short compInd;
char university[20];
short univInd;
char major[10];
short majorInd;
short salaryInd;
EXEC SQL END DECLARE SECTION;
class TbInTrig
{
public:
int NormalUpdate(void);
int UpdateWithInsteadOfTrigger(void);
int MutliTableUpdate(void);
int CreateViewStaffV(void);
private:
int StaffvContentDisplay(char *);
int InsteadOfUpdateTriggerCreate(void);
int CreateTablesAndView(void);
int CreatePersonsVTriggers(void);
int PersonsVContentDisplay(void);
};
// This function creates a view 'staffv' of the table 'staff'
int TbInTrig::CreateViewStaffV(void)
{
struct sqlca sqlca;
cout << "\n CREATE A VIEW 'staffv' OF THE TABLE 'staff'" << endl;
cout << "\n INVOKE THE STATEMENT:\n" << endl;
cout << " CREATE VIEW staffv(ID, NAME, DEPT, JOB, YEARS, SALARY, COMM)"
<< "\n AS SELECT * FROM staff WHERE ID >= 310" << endl;
EXEC SQL CREATE VIEW staffv(ID, NAME, DEPT, JOB, YEARS, SALARY, COMM)
AS SELECT * FROM staff WHERE ID >= 310;
EMB_SQL_CHECK("create--view");
EXEC SQL COMMIT;
return 0;
} //TbInTrig::CreateViewStaffV
// Helper function: This function displays the results of a query specified
// by 'selectstmt' on the 'staffv' view
int TbInTrig::StaffvContentDisplay(char *selectstmt)
{
struct sqlca sqlca;
cout << "\n " << selectstmt << "\n\n";
cout << " ID NAME DEPT JOB YEARS SALARY COMM" << endl;
cout << " --- -------- ---- ----- ----- -------- -------" << endl;
// Declare a CURSOR to store the results of the query specified by
// 'selectstmt'
strcpy(strStmt,
selectstmt);
EXEC SQL PREPARE S1 FROM :strStmt;
EMB_SQL_CHECK("after prepare");
EXEC SQL DECLARE c1 CURSOR FOR s1;
EMB_SQL_CHECK("declare cursor");
EXEC SQL OPEN c1;
EMB_SQL_CHECK("cursor -- open");
// Retrieve and display the results of the query
EXEC SQL FETCH c1 INTO :id, :name, :dept, :job:jobInd, :years:yearsInd,
:salary, :comm:commInd;
EMB_SQL_CHECK("cursor -- fetch");
while (sqlca.sqlcode != 100)
{
cout << " " << setw(3) << id;
cout.setf(ios::left, ios::adjustfield);
cout << " " << setw(8) << name;
cout.setf(ios::right, ios::adjustfield);
cout << " " << setw(4) << dept;
if (jobInd >= 0)
{
cout << " " << setw(5) << job;
}
else
{
cout << " -";
}
if (yearsInd >= 0)
{
cout << " " << setw(5) << years;
}
else
{
cout << " -";
}
cout << " " << setw(7) << setprecision(2) << salary;
if (commInd >= 0)
{
cout << " " << setw(7) << comm;
}
else
{
cout << " -";
}
cout << endl;
EXEC SQL FETCH c1 INTO :id, :name, :dept, :job:jobInd, :years:yearsInd,
:salary, :comm:commInd;
EMB_SQL_CHECK("cursor -- fetch");
}
EXEC SQL CLOSE c1;
EMB_SQL_CHECK("cursor -- close");
return 0;
} //TbInTrig::StaffTbContentDisplay
// This function demonstrates an UPDATE operation before an
// 'INSTEAD OF UPDATE' trigger is created
int TbInTrig::InsteadOfUpdateTriggerCreate(void)
{
int rc = 0;
struct sqlca sqlca;
cout << "\n CREATE AN 'INSTEAD OF UPDATE' TRIGGER CALLED 'staff_raise'\n";
// Create a trigger which apart from the original update, raises the salary
// further based on the number of years the employee has served
strcpy(strStmt,
"CREATE TRIGGER staff_raise INSTEAD OF UPDATE ON staffv"
" REFERENCING NEW AS n OLD AS o "
" FOR EACH ROW "
" BEGIN ATOMIC "
" VALUES(CASE "
" WHEN n.ID = o.ID THEN 0 "
" ELSE RAISE_ERROR('70002', 'Must not change ID') "
" END); "
" UPDATE STAFF AS S "
" SET (ID, NAME, DEPT, JOB, YEARS, COMM, SALARY) "
" = (n.ID, n.NAME, n.DEPT, n.JOB, n.YEARS, n.COMM, "
" CASE "
" WHEN n.YEARS IS NULL THEN o.salary "
" WHEN n.YEARS <= 2 THEN n.salary + 500 "
" WHEN n.YEARS <= 4 THEN n.salary + 1000 "
" WHEN n.YEARS <= 6 THEN n.salary + 2000 "
" WHEN n.YEARS <= 8 THEN n.salary + 3500 "
" WHEN n.YEARS <= 10 THEN n.salary + 5500 "
" ELSE n.salary + 6000 "
" END) "
" WHERE n.ID = S.ID; "
" END ");
cout << "\n CREATE TRIGGER staff_raise INSTEAD OF UPDATE ON staffv"
<< "\n REFERENCING NEW AS n OLD AS o "
<< "\n FOR EACH ROW "
<< "\n BEGIN ATOMIC "
<< "\n VALUES(CASE "
<< "\n WHEN n.ID = o.ID THEN 0 "
<< "\n ELSE RAISE_ERROR('70002','Must not change ID')"
<< "\n END); "
<< "\n UPDATE STAFF AS S "
<< "\n SET (ID, NAME, DEPT, JOB, YEARS, COMM, SALARY) "
<< "\n = (n.ID, n.NAME, n.DEPT, n.JOB, n.YEARS, n.COMM, "
<< "\n CASE "
<< "\n WHEN n.YEARS IS NULL THEN o.salary "
<< "\n WHEN n.YEARS <= 2 THEN n.salary + 500 "
<< "\n WHEN n.YEARS <= 4 THEN n.salary + 1000 "
<< "\n WHEN n.YEARS <= 6 THEN n.salary + 2000 "
<< "\n WHEN n.YEARS <= 8 THEN n.salary + 3500 "
<< "\n WHEN n.YEARS <= 10 THEN n.salary + 5500 "
<< "\n ELSE n.salary + 6000 "
<< "\n END) "
<< "\n WHERE n.ID = S.ID; "
<< "\n END\n";
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("trigger -- create");
EXEC SQL COMMIT;
EMB_SQL_CHECK("create trigger -- commit");
return 0;
} // TbInTrig::InsteadOfUpdateTriggerUse
// This function demonstrates an UPDATE operation before an
// 'INSTEAD OF UPDATE' trigger has been created
int TbInTrig::NormalUpdate(void)
{
int rc = 0;
struct sqlca sqlca;
char *selectstring = "SELECT * FROM staffv WHERE ID = 340";
cout << "\n -----------------------------------------------------------";
cout << "\n USE THE SQL STATEMENTS:";
cout << "\n\n ROLLBACK";
cout << "\n UPDATE";
cout << "\n\n TO DISPLAY THE RESULTS OF AN UPDATE STATEMENT ON THE VIEW"
<< " 'staffv'"
<< "\n BEFORE AN 'INSTEAD OF UPDATE' TRIGGER IS CREATED.\n";
// Display the contents of the row in 'staffv' that is going to be
// updated
cout << "\n CONTENT OF A ROW IN 'staffv' VIEW BEFORE IT IS UPDATED\n";
rc = StaffvContentDisplay(selectstring);
// Update the 'staffv' view
cout << "\n INVOKE THE STATEMENT:\n";
cout << "\n UPDATE staffv SET years=4,COMM=50 WHERE ID = 340\n";
strcpy(strStmt,
"UPDATE staffv SET years=4,COMM=50 WHERE ID = 340");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("table -- update");
// Display the contents of the row in 'staffv' after updating it
cout << "\n CONTENTS OF THE ROW IN 'staffv' AFTER UPDATING IT\n";
rc = StaffvContentDisplay(selectstring);
// Rollback the changes made to the view
EXEC SQL ROLLBACK;
return 0;
} // TbInTrig::NormalUpdate
// This function demonstrate an UPDATE operation after an 'INSTEAD OF UPDATE'
// trigger has been created
int TbInTrig::UpdateWithInsteadOfTrigger(void)
{
int rc = 0;
struct sqlca sqlca;
char *selectstring = "SELECT * FROM staffv WHERE ID = 340";
cout << "\n -----------------------------------------------------------";
cout << "\n USE THE SQL STATEMENTS:\n";
cout << "\n CREATE TRIGGER";
cout << "\n UPDATE";
cout << "\n ROLLBACK";
cout << "\n COMMIT\n";
cout << "\n TO DISPLAY THE RESULTS OF THE SAME UPDATE STATEMENT ON THE "
<< "VIEW "
<< "\n 'staffv' AFTER CREATING AN 'INSTEAD OF UPDATE' TRIGGER.\n";
// Create an 'INSTEAD OF UPDATE' trigger
rc = InsteadOfUpdateTriggerCreate();
// Display the row to be updated in 'staffv' before an UPDATE statement is
// issued
cout << "\n CONTENTS OF THE ROW IN 'staffv' BEFORE IT IS UPDATED\n";
rc = StaffvContentDisplay(selectstring);
// Issue an UPDATE statement to update the 'staffv' view
cout << "\n INVOKE THE SAME STATEMENT:\n";
cout << "\n UPDATE staffv SET years=4,COMM=50 WHERE ID = 340\n";
strcpy(strStmt,
"UPDATE staffv SET years=4,COMM=50 WHERE ID = 340");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("table -- update");
// Display the contents of the row in 'staffv' after updating it with the
// UPDATE statement
cout << "\n CONTENTS OF THE ROW IN 'staffv' AFTER INVOKING THE UPDATE "
<< "STATEMENT,"
<< "\n WHICH NOW CAUSES THE 'INSTEAD OF UPDATE' TRIGGER TO FIRE\n";
rc = StaffvContentDisplay(selectstring);
// Rollback changes made to the view
EXEC SQL ROLLBACK;
// Drop the trigger
EXEC SQL DROP TRIGGER staff_raise;
EMB_SQL_CHECK("trigger -- drop");
EXEC SQL COMMIT;
// Drop the view
cout << "\n DROP VIEW 'STAFFV'\n";
EXEC SQL DROP VIEW STAFFV;
return 0;
} // TbInTrig::UpdateWithInsteadOfTrigger
// This function creates tables: PERSONS, STUDENTS and EMPLOYEES and
// creates a view called PERSONS_V
int TbInTrig::CreateTablesAndView(void)
{
struct sqlca sqlca;
// Create the table PERSONS
cout << "\n INVOKE THE STATEMENTS:\n";
cout << "\n CREATE TABLE PERSONS(ssn INT NOT NULL, name VARCHAR(20)"
" NOT NULL)" << endl;
EXEC SQL CREATE TABLE PERSONS(ssn INT NOT NULL, name VARCHAR(20) NOT NULL);
EMB_SQL_CHECK("table -- create");
// Create the table EMPLOYEES
cout << "\n CREATE TABLE EMPLOYEES(ssn INT NOT NULL,"
<< "\n company VARCHAR(20) NOT NULL,"
<< "\n salary DECIMAL(9,2))\n";
EXEC SQL CREATE TABLE EMPLOYEES(ssn INT NOT NULL,
company VARCHAR(20) NOT NULL,
salary DECIMAL(9,2));
EMB_SQL_CHECK("table -- create");
// Create the table STUDENTS
cout << "\n CREATE TABLE STUDENTS(ssn INT NOT NULL,"
<< "\n university VARCHAR(20) NOT NULL,"
<< "\n major VARCHAR(10))\n";
EXEC SQL CREATE TABLE STUDENTS(ssn INT NOT NULL,
university VARCHAR(20) NOT NULL,
major VARCHAR(10));
EMB_SQL_CHECK("table -- create");
// Create the view PERSONS_V
cout << "\n CREATE VIEW PERSONS_V(ssn, name, company, "
<< "\n salary, university, major) "
<< "\n AS SELECT P.ssn, name, company, "
<< "\n salary, university, major "
<< "\n FROM PERSONS P LEFT OUTER JOIN EMPLOYEES E "
<< "\n ON P.ssn = E.ssn "
<< "\n LEFT OUTER JOIN STUDENTS S "
<< "\n ON P.ssn = S.ssn\n";
EXEC SQL CREATE VIEW PERSONS_V(ssn, name, company,
salary, university, major)
AS SELECT P.ssn, name, company,
salary, university, major
FROM PERSONS P LEFT OUTER JOIN EMPLOYEES E
ON P.ssn = E.ssn
LEFT OUTER JOIN STUDENTS S
ON P.ssn = S.ssn;
EMB_SQL_CHECK("view -- create");
EXEC SQL COMMIT;
EMB_SQL_CHECK("transaction -- commit");
return 0;
} // TbInTrig::CreateTablesAndView
// This function creates INSTEAD OF triggers: INSERT_PERSONS_V,
// UPDATE_PERSONS_V and DELETE_PERSONS_V on the view PERSONS_V
int TbInTrig::CreatePersonsVTriggers(void)
{
int rc = 0;
struct sqlca sqlca;
// Create the INSTEAD OF INSERT trigger 'INSERT_PERSONS_V'
cout << "\n CREATE AN 'INSTEAD OF INSERT' TRIGGER CALLED "
<< "'INSERT_PERSONS_V':\n"
<< "\n INVOKE THE STATEMENT:\n";
cout << "\n CREATE TRIGGER INSERT_PERSONS_V "
<< "\n INSTEAD OF INSERT ON PERSONS_V "
<< "\n REFERENCING NEW AS n FOR EACH ROW "
<< "\n BEGIN ATOMIC "
<< "\n INSERT INTO PERSONS VALUES (n.ssn, n.name); "
<< "\n IF n.university IS NOT NULL THEN "
<< "\n INSERT INTO STUDENTS "
<< "\n VALUES(n.ssn, n.university, n.major); "
<< "\n END IF; "
<< "\n IF n.company IS NOT NULL THEN "
<< "\n INSERT INTO EMPLOYEES "
<< "\n VALUES(n.ssn, n.company, n.salary); "
<< "\n END IF; "
<< "\n END\n";
strcpy(strStmt,
"CREATE TRIGGER INSERT_PERSONS_V "
" INSTEAD OF INSERT ON PERSONS_V "
" REFERENCING NEW AS n FOR EACH ROW "
" BEGIN ATOMIC "
" INSERT INTO PERSONS VALUES (n.ssn, n.name); "
" IF n.university IS NOT NULL THEN "
" INSERT INTO STUDENTS "
" VALUES(n.ssn, n.university, n.major); "
" END IF; "
" IF n.company IS NOT NULL THEN "
" INSERT INTO EMPLOYEES "
" VALUES(n.ssn, n.company, n.salary); "
" END IF; "
" END ");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("trigger -- create");
EXEC SQL COMMIT;
EMB_SQL_CHECK("create trigger -- commit");
// Create the INSTEAD OF DELETE trigger 'DELETE_PERSONS_V'
cout << "\n CREATE AN 'INSTEAD OF DELETE' TRIGGER CALLED "
<< "'DELETE_PERSONS_V':\n"
<< "\n INVOKE THE STATEMENT:\n";
cout << "\n CREATE TRIGGER DELETE_PERSONS_V "
<< "\n INSTEAD OF DELETE ON PERSONS_V "
<< "\n REFERENCING OLD AS o FOR EACH ROW "
<< "\n BEGIN ATOMIC "
<< "\n DELETE FROM STUDENTS WHERE ssn = o.ssn; "
<< "\n DELETE FROM EMPLOYEES WHERE ssn = o.ssn; "
<< "\n DELETE FROM PERSONS WHERE ssn = o.ssn; "
<< "\n END\n";
strcpy(strStmt,
"CREATE TRIGGER DELETE_PERSONS_V "
" INSTEAD OF DELETE ON PERSONS_V "
" REFERENCING OLD AS o FOR EACH ROW "
" BEGIN ATOMIC "
" DELETE FROM STUDENTS WHERE ssn = o.ssn; "
" DELETE FROM EMPLOYEES WHERE ssn = o.ssn; "
" DELETE FROM PERSONS WHERE ssn = o.ssn; "
" END ");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("trigger -- create");
EXEC SQL COMMIT;
EMB_SQL_CHECK("create trigger -- commit");
// Create the INSTEAD OF UPDATE trigger 'UPDATE_PERSONS_V'
cout << "\n CREATE AN 'INSTEAD OF UPDATE' TRIGGER CALLED "
<< "'UPDATE_PERSONS_V':\n"
<< "\n INVOKE THE STATEMENT:\n";
cout << "\n CREATE TRIGGER UPDATE_PERSONS_V "
<< "\n INSTEAD OF UPDATE ON PERSONS_V "
<< "\n REFERENCING OLD AS o NEW AS n "
<< "\n FOR EACH ROW "
<< "\n BEGIN ATOMIC "
<< "\n UPDATE PERSONS "
<< "\n SET (ssn, name) = (n.ssn, n.name) "
<< "\n WHERE ssn = o.ssn; "
<< "\n IF n.university IS NOT NULL "
<< "\n AND o.university IS NOT NULL THEN "
<< "\n UPDATE STUDENTS "
<< "\n SET (ssn, university, major) "
<< "\n = (n.ssn, n.university, n.major) "
<< "\n WHERE ssn = o.ssn; "
<< "\n ELSEIF n.university IS NULL THEN "
<< "\n DELETE FROM STUDENTS WHERE ssn = o.ssn; "
<< "\n ELSE "
<< "\n INSERT INTO STUDENTS "
<< "\n VALUES(n.ssn, n.university, n.major); "
<< "\n END IF; "
<< "\n IF n.company IS NOT NULL "
<< "\n AND o.company IS NOT NULL THEN "
<< "\n UPDATE EMPLOYEES "
<< "\n SET (ssn, company, salary) "
<< "\n = (n.ssn, n.company, n.salary) "
<< "\n WHERE ssn = o.ssn; "
<< "\n ELSEIF n.company IS NULL THEN "
<< "\n DELETE FROM EMPLOYEES WHERE ssn = o.ssn; "
<< "\n ELSE "
<< "\n INSERT INTO EMPLOYEES "
<< "\n VALUES(n.ssn, n.company, n.salary); "
<< "\n END IF; "
<< "\n END\n";
strcpy(strStmt,
"CREATE TRIGGER UPDATE_PERSONS_V "
" INSTEAD OF UPDATE ON PERSONS_V "
" REFERENCING OLD AS o NEW AS n "
" FOR EACH ROW "
" BEGIN ATOMIC "
" UPDATE PERSONS "
" SET (ssn, name) = (n.ssn, n.name) "
" WHERE ssn = o.ssn; "
" IF n.university IS NOT NULL "
" AND o.university IS NOT NULL THEN "
" UPDATE STUDENTS "
" SET (ssn, university, major) "
" = (n.ssn, n.university, n.major) "
" WHERE ssn = o.ssn; "
" ELSEIF n.university IS NULL THEN "
" DELETE FROM STUDENTS WHERE ssn = o.ssn; "
" ELSE "
" INSERT INTO STUDENTS "
" VALUES(n.ssn, n.university, n.major); "
" END IF; "
" IF n.company IS NOT NULL "
" AND o.company IS NOT NULL THEN "
" UPDATE EMPLOYEES "
" SET (ssn, company, salary) "
" = (n.ssn, n.company, n.salary) "
" WHERE ssn = o.ssn; "
" ELSEIF n.company IS NULL THEN "
" DELETE FROM EMPLOYEES WHERE ssn = o.ssn; "
" ELSE "
" INSERT INTO EMPLOYEES "
" VALUES(n.ssn, n.company, n.salary); "
" END IF; "
" END");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("trigger -- create");
EXEC SQL COMMIT;
EMB_SQL_CHECK("create trigger -- commit");
return 0;
} // TbInTrig::CreatePersonsVTriggers
// This function demonstrates how to update a number of tables through a
// common view and the use of a set of 'INSTEAD OF' triggers
int TbInTrig::MutliTableUpdate(void)
{
int rc = 0;
struct sqlca sqlca;
cout << "\n -----------------------------------------------------------";
cout << "\n USE THE SQL STATEMENTS:\n\n";
cout << " CREATE TABLE\n";
cout << " CREATE VIEW\n";
cout << " CREATE TRIGGER\n";
cout << " INSERT\n";
cout << " UPDATE\n";
cout << " DELETE\n";
cout << " COMMIT\n";
cout << " ROLLBACK\n\n";
cout
<< " TO UPDATE DATA IN TABLES 'PERSONS', 'STUDENTS' AND 'EMPLOYEES'\n"
<< " THROUGH A VIEW 'PERSONS_V' USING 'INSTEAD OF' TRIGGERS.\n\n"
<< " NOTE: THE VIEW IS NEITHER INSERTABLE, UPDATABLE NOR DELETABLE, SO"
<< "\n IN ORDER TO PERFORM THESE TABLE OPERATIONS, A FULL SET OF\n"
<< " 'INSTEAD OF' TRIGGERS NEEDS TO BE GENERATED. THE TRIGGERS MODIFY\n"
<< " THE CONTENTS OF EACH TABLE INDIVIDUALLY WHEN AN OPERATION IS\n"
<< " ATTEMPTED ON THE VIEW\n";
cout
<< "\n CREATE TABLES: 'PERSONS', 'EMPLOYEES' AND 'STUDENTS' AND CREATE "
<< "A\n VIEW 'PERSONS_V'\n";
// Create the tables PERSONS, STUDENTS, EMPLOYEES, and the view
// PERSONS_V
rc = CreateTablesAndView();
// Create the set of INSTEAD OF triggers
rc = CreatePersonsVTriggers();
// Insert values in tables PERSONS, STUDENTS, and EMPLOYEES by inserting
// the values in the view PERSONS_V. This action will trigger the INSTEAD
// OF INSERT trigger which will then insert the values in the individual
// tables
cout
<< "\n INSERT VALUES IN TABLES 'PERSONS', 'STUDENTS' AND 'EMPLOYEES'"
<< "\n THROUGH THE VIEW 'PERSONS_V'\n"
<< "\n INVOKE THE STATEMENT:\n";
cout
<< "\n INSERT INTO PERSONS_V"
<< "\n VALUES(123456, 'Smith', NULL, NULL, NULL, NULL), "
<< "\n (234567, 'Jones', 'Wmart', 20000, NULL, NULL), "
<< "\n (345678, 'Miller', NULL, NULL, 'Harvard', 'Math'), "
<< "\n (456789, 'McNuts', 'SelfEmp', 60000, 'UCLA', 'CS')\n";
strcpy(strStmt,
"INSERT INTO PERSONS_V VALUES "
" (123456, 'Smith', NULL, NULL, NULL, NULL), "
" (234567, 'Jones', 'Wmart', 20000, NULL, NULL), "
" (345678, 'Miller', NULL, NULL, 'Harvard', 'Math'), "
" (456789, 'McNuts', 'SelfEmp', 60000, 'UCLA', 'CS') ");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("tables--insert");
// Display view content after the insertion of rows
cout << "\n CONTENTS OF 'PERSONS_V' AFTER THE 'INSERT' STATEMENT\n";
rc = PersonsVContentDisplay();
// Update values in tables PERSONS, STUDENTS, and EMPLOYEES by updating the
// values in the view PERSONS_V. This action will trigger the INSTEAD OF
// UPDATE trigger which will then update the values in the individual
// tables
cout << "\n UPDATE THE TABLES 'PERSONS', 'STUDENTS' AND 'EMPLOYEES'"
<< "\n THROUGH THE VIEW 'PERSONS_V'\n"
<< "\n INVOKE THE STATEMENTS:\n";
cout
<< "\n UPDATE PERSONS_V"
<< "\n SET (name, company, salary) ="
<< " ('Johnson', 'Mickburgs', 15000)"
<< "\n WHERE SSN = 123456\n"
<< "\n UPDATE PERSONS_V"
<< "\n SET (company, salary, university) = ('IBM', 70000, NULL)"
<< "\n WHERE SSN = 345678\n";
strcpy(strStmt,
"UPDATE PERSONS_V "
" SET (name, company, salary) = ('Johnson', 'Mickburgs', 15000) "
" WHERE SSN = 123456");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("statement -- execute immediate");
strcpy(strStmt,
"UPDATE PERSONS_V SET (company, salary, university) "
" = ('IBM', 70000, NULL) "
" WHERE SSN = 345678");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("statement -- execute immediate");
// Display view content after updating
cout << "\n CONTENTS OF 'PERSONS_V' AFTER THE 'UPDATE' STATEMENTS\n";
rc = PersonsVContentDisplay();
// Delete rows from tables PERSONS, STUDENTS, and EMPLOYEES by deleting the
// rows in the view PERSONS_V. This action will trigger the INSTEAD OF
// DELETE trigger which will then delete rows from the individual tables
cout
<< "\n DELETE ROWS FROM TABLES 'PERSONS', 'STUDENTS' AND 'EMPLOYEES'"
<< "\n THROUGH THE VIEW 'PERSONS_V'\n"
<< "\n INVOKE THE STATEMENT:\n";
cout << "\n DELETE FROM PERSONS_V WHERE NAME = 'Jones'\n";
strcpy(strStmt,
"DELETE FROM PERSONS_V WHERE NAME = 'Jones'");
EXEC SQL EXECUTE IMMEDIATE :strStmt;
EMB_SQL_CHECK("statement -- execute immediate");
// Display view content after deleting rows
cout << "\n CONTENTS OF 'PERSONS_V' AFTER THE 'DELETE' STATEMENT\n";
rc = PersonsVContentDisplay();
EXEC SQL ROLLBACK;
// Drop the INSTEAD OF triggers
cout << "\n DROP TRIGGERS: INSERT_PERSONS_V, DELETE_PERSONS_V, AND "
<< "UPDATE_PERSONS_V";
EXEC SQL DROP TRIGGER INSERT_PERSONS_V;
EMB_SQL_CHECK("trigger -- drop");
EXEC SQL DROP TRIGGER DELETE_PERSONS_V;
EMB_SQL_CHECK("trigger -- drop");
EXEC SQL DROP TRIGGER UPDATE_PERSONS_V;
EMB_SQL_CHECK("trigger -- drop");
// Drop the tables PERSONS, STUDENTS, EMPLOYEES and the view PERSONS_V
cout << "\n DROP TABLES: PERSONS, STUDENTS, AND EMPLOYEES"
<< "\n DROP VIEW: PERSONS_V\n";
EXEC SQL DROP TABLE PERSONS;
EXEC SQL DROP VIEW PERSONS_V;
EXEC SQL DROP TABLE STUDENTS;
EXEC SQL DROP TABLE EMPLOYEES;
EXEC SQL COMMIT;
return 0;
}
// This function displays the contents of the 'STAFFV' view
int TbInTrig::PersonsVContentDisplay(void)
{
struct sqlca sqlca;
cout << "\n SELECT * FROM persons_v ORDER BY ssn\n\n";
cout << " SSN NAME COMPANY SALARY UNIVERSITY MAJOR\n";
cout << " ------ ------- --------- --------- ---------- -----\n";
// Declare a CURSOR to store the results of the query
strcpy(strStmt,
"SELECT SSN, NAME, COMPANY, SALARY, UNIVERSITY, MAJOR"
" FROM persons_v ORDER BY ssn");
EXEC SQL PREPARE S2 FROM :strStmt;
EMB_SQL_CHECK("after prepare");
EXEC SQL DECLARE c2 CURSOR FOR s2;
EMB_SQL_CHECK("declare cursor");
EXEC SQL OPEN c2;
EMB_SQL_CHECK("open cursor");
// Retrieve and display the results of the query
EXEC SQL FETCH c2 INTO :ssn, :personsname, :company:compInd,
:salary:salaryInd, :university:univInd,
:major:majorInd;
EMB_SQL_CHECK("fetch");
while (sqlca.sqlcode != 100)
{
cout.setf(ios::left, ios::adjustfield);
cout << " " << setw(3) << ssn << " " << setw(8) << personsname;
if (compInd >= 0)
{
cout << setw(9) << company;
}
else
{
cout << " - ";
}
if (salaryInd >= 0)
{
cout << " " << setw(9) << setprecision(2) << salary;
}
else
{
cout << " - ";
}
if (univInd >= 0)
{
cout << " " << setw(10) << university;
}
else
{
cout << " - ";
}
if (majorInd >= 0)
{
cout << " " << setw(5) << major << endl;
}
else
{
cout << " - " << endl;
}
EXEC SQL FETCH c2 INTO :ssn, :personsname, :company:compInd,
:salary:salaryInd, :university:univInd,
:major:majorInd;
EMB_SQL_CHECK("fetch");
}
EXEC SQL CLOSE C2;
EMB_SQL_CHECK("close");
return 0;
} // TbInTrig::PersonsVContentDisplay
int main(int argc, char *argv[])
{
int rc = 0;
struct sqlca sqlca;
CmdLineArgs check;
DbEmb db;
TbInTrig intrig;
// check the command line arguments
rc = check.CmdLineArgsCheck1(argc, argv, db);
if (rc != 0)
{
return rc;
}
cout.setf(ios::fixed, ios::floatfield);
cout << "\n THIS SAMPLE SHOWS HOW TO USE 'INSTEAD OF' TRIGGERS.\n";
// Connect to the database
rc = db.Connect();
if (rc != 0)
{
return rc;
}
// Create a view 'staffv' of the table 'staff'
rc = intrig.CreateViewStaffV();
// Demonstrate an UPDATE operation before an INSTEAD OF UPDATE trigger
// is created
rc = intrig.NormalUpdate();
// Demonstrate the same UPDATE operation after an INSTEAD OF UPDATE trigger
// is created
rc = intrig.UpdateWithInsteadOfTrigger();
// Demonstrate how to update a number of tables through a common view and
// the use of a set of 'INSTEAD OF' triggers
rc = intrig.MutliTableUpdate();
// Disconnect from the database
rc = db.Disconnect();
if (rc != 0)
{
return rc;
}
return 0;
} // main