в 13:45, 26 мая 2010

2010-05-26T13:45:19Z

Admin: 1 версия

2010-05-26T09:58:28Z

1 версия

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==Check new value before insert and update==



<source lang="sql">

SQL>
SQL> CREATE TABLE MyTable (
2 num_col NUMBER,
3 char_col VARCHAR2(60)
4 );
Table created.
SQL>
SQL>
SQL> CREATE OR REPLACE TRIGGER OnlyPositive
2 BEFORE INSERT OR UPDATE OF num_col
3 ON MyTable
4 FOR EACH ROW
5 BEGIN
6 IF :new.num_col < 0 THEN
7 RAISE_APPLICATION_ERROR(-20100, "Please insert a positive value");
8 END IF;
9 END OnlyPositive;
10 /
Trigger created.
SQL>
SQL> INSERT INTO MyTable (num_col, char_col)
2 VALUES (1, "This is row 1");
1 row created.
SQL>
SQL> INSERT INTO MyTable (num_col, char_col)
2 VALUES (-1, "This is row -1");
INSERT INTO MyTable (num_col, char_col)
*
ERROR at line 1:
ORA-20100: Please insert a positive value
ORA-06512: at "sqle.ONLYPOSITIVE", line 3
ORA-04088: error during execution of trigger "sqle.ONLYPOSITIVE"

SQL>
SQL> drop table MyTable;
Table dropped.
SQL>
SQL>

</source>

==Create a "BEFORE UPDATE" Trigger==



<source lang="sql">

SQL> -- create demo table
SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 First_Name VARCHAR2(10 BYTE),
4 Last_Name VARCHAR2(10 BYTE),
5 Start_Date DATE,
6 End_Date DATE,
7 Salary Number(8,2),
8 City VARCHAR2(10 BYTE),
9 Description VARCHAR2(15 BYTE)
10 )
11 /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created.
SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester
8 rows selected.
SQL>
SQL> -- BEFORE UPDATE Trigger
SQL> CREATE OR REPLACE TRIGGER employee_before_update
2 BEFORE UPDATE
3 ON employee
4 FOR EACH ROW
5
6 DECLARE
7 v_username varchar2(10);
8
9 BEGIN
10 -- Find username of person performing UPDATE on the table
11 SELECT user INTO v_username
12 FROM dual;
13
14 dbms_output.put_line("By: "||v_username);
15 dbms_output.put_line("Date: "||sysdate);
16 dbms_output.put_line(":new.id: "||:new.id);
17 dbms_output.put_line(":new.first_name: "||:new.first_name);
18 dbms_output.put_line(":new.last_name: "||:new.last_name);
19 dbms_output.put_line(":old.id: "||:old.id);
20 dbms_output.put_line(":old.first_name: "||:old.first_name);
21 dbms_output.put_line(":old.last_name: "||:old.last_name);
22
23 END;
24 /
Trigger created.
SQL>
SQL> update employee set first_name="newName";
By: sqle
Date: 09-SEP-06
:new.id: 01
:new.first_name: newName
:new.last_name: Martin
:old.id: 01
:old.first_name: Jason
:old.last_name: Martin
By: sqle
Date: 09-SEP-06
:new.id: 02
:new.first_name: newName
:new.last_name: Mathews
:old.id: 02
:old.first_name: Alison
:old.last_name: Mathews
By: sqle
Date: 09-SEP-06
:new.id: 03
:new.first_name: newName
:new.last_name: Smith
:old.id: 03
:old.first_name: James
:old.last_name: Smith
By: sqle
Date: 09-SEP-06
:new.id: 04
:new.first_name: newName
:new.last_name: Rice
:old.id: 04
:old.first_name: Celia
:old.last_name: Rice
By: sqle
Date: 09-SEP-06
:new.id: 05
:new.first_name: newName
:new.last_name: Black
:old.id: 05
:old.first_name: Robert
:old.last_name: Black
By: sqle
Date: 09-SEP-06
:new.id: 06
:new.first_name: newName
:new.last_name: Green
:old.id: 06
:old.first_name: Linda
:old.last_name: Green
By: sqle
Date: 09-SEP-06
:new.id: 07
:new.first_name: newName
:new.last_name: Larry
:old.id: 07
:old.first_name: David
:old.last_name: Larry
By: sqle
Date: 09-SEP-06
:new.id: 08
:new.first_name: newName
:new.last_name: Cat
:old.id: 08
:old.first_name: James
:old.last_name: Cat
8 rows updated.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>

</source>

==Create a BEFORE UPDATE trigger on the emp table==



<source lang="sql">

SQL> CREATE TABLE emp (
2 id NUMBER PRIMARY KEY,
3 fname VARCHAR2(50),
4 lname VARCHAR2(50)
5 );
Table created.
SQL>
SQL> INSERT INTO emp (id, fname, lname)VALUES (1, "A", "B");
1 row created.
SQL> INSERT INTO emp (id, fname, lname)VALUES (2, "C", "D");
1 row created.
SQL> INSERT INTO emp (id, fname, lname)VALUES (3, "E", "F");
1 row created.
SQL> INSERT INTO emp (id, fname, lname)VALUES (4, "G", "H");
1 row created.
SQL> INSERT INTO emp (id, fname, lname)VALUES (5, "G", "Z");
1 row created.
SQL>
SQL>
SQL> SET SERVEROUTPUT ON
SQL>
SQL>
SQL> CREATE OR REPLACE TRIGGER emp_trig
2 BEFORE UPDATE OF fname
3 ON emp
4 FOR EACH ROW
5 BEGIN
6 DBMS_OUTPUT.PUT_LINE("First Name "||:OLD.fname||" has change to "||:NEW.fname);
7 END;
8 /
Trigger created.
SQL>
SQL>
SQL> SELECT trigger_name, status FROM user_triggers;
TRIGGER_NAME STATUS
------------------------------ --------
EMP_TRIG ENABLED
INVENTORY_TRG DISABLED
DEMO_BIFER DISABLED
DEPT_SAL_TRG DISABLED
SYSTEMALTERUSER DISABLED
USAGE_START DISABLED
USAGE_STOP DISABLED
USER_LOGON_MODULE_CHECK DISABLED
8 rows selected.
SQL>
SQL> drop table emp;
Table dropped.
SQL>

</source>

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Oracle PL/SQL/Trigger/Before Update Trigger - История изменений

в 13:45, 26 мая 2010

Admin: 1 версия