在更新觸發在oracle？

Question

我創建2名錶的員工和客戶。而員工表的代碼是在這裏：

create table employees(
employeeNumber  number not null, 
lastName   varchar2(30) not null, 
firstName   varchar2(30) not null, 
email    varchar2(50) not null, 
officeCode   varchar2(10) not null, 
assignTo   number default null, 
jobTitle   varchar2(100) not null, 
primary key (employeeNumber), 
foreign key (officeCode) references offices(officeCode), 
foreign key (assignTo) references employees(employeeNumber) 
); 

這裏assignTo是他自己的表，員工的外鍵和employeeNumber是汽車increment.Some插入樣品是在這裏：

insert into employees (lastName,firstName,email,officeCode,jobTitle) 
values ('hasan','rumy','md.rejaulhasanrumy@gmail.com','123','manager'); 
insert into employees (lastName,firstName,email,officeCode,assignTo,jobTitle) 
values ('hasan','rakib','kalorakib@gmail.com','123', 1 ,'assistant manager'); 

客戶表的代碼是在這裏：

create table customers (
customerNumber number not null, 
customerName  varchar2(50) not null, 
phone    varchar2(20) not null, 
address   varchar2(70) not null, 
city    varchar2(50) not null, 
postalCode  varchar2(15) not null, 
country   varchar2(40) not null, 
salesRepEmployeeNumber number default null, 
primary key(customerNumber), 
foreign key (salesRepEmployeeNumber) references employees (employeeNumber) 
); 

customerNumber之是汽車increment.some樣本投放是在這裏：

insert into customers 
(customerName,phone,address,city,postalCode,country,salesRepEmployeeNumber) 
values ('roxy','017456','holy park','kolia','Z143','something',1); 

現在我創建員工表的更新employeeNumber列之前，其執行對級聯更新觸發器和代碼是在這裏：

create or replace trigger employees_update 
before update of employeeNumber on employees 
for each row 
begin 
update employees 
set 
assignTo = :new.employeeNumber 
where assignTo = :old.employeeNumber; 
update customers set 
salesRepEmployeeNumber = :new.employeeNumber 
where salesRepEmployeeNumber = :old.employeeNumber; 
end; 
/

高於一切是正確的預言，但問題是什麼時候更新員工table.The更新代碼是在這裏：

update employees set employeeNumber = 134 where employeeNumber = 1; 

的問題是在這裏：

ORA-04091: table RUMY.EMPLOYEES is mutating, trigger/function may not see it 
ORA-06512: at "RUMY.EMPLOYEES_UPDATE", line 2 
ORA-04088: error during execution of trigger 'RUMY.EMPLOYEES_UPDATE' 

1. update employees set employeeNumber = 134 where employeeNumber = 1; 

據我所知，這是一個系統問題，所以我犯了錯誤？我不能讓員工表的外鍵assignTo？還注意到同樣的事情在mysql中正常工作。先行謝謝你回答這個長問題。

Answer 1

當你發現，你不能從同一個表中選擇一個行級觸發器被定義爲反對;它會導致表異常異常。

然後 - 假設至少甲骨文11，這將需要在早期版本

CREATE OR REPLACE TRIGGER employees_update 
    FOR UPDATE ON employees 
    COMPOUND TRIGGER 

    TYPE employeeNumberRec IS RECORD 
    (oldEmployeeNumber employees.employeeNumber%TYPE 
    ,newEmployeeNumber employees.employeeNumber%TYPE); 
    TYPE employeeNumbersTbl IS TABLE OF employeeNumberRec; 
    g_employeeNumbers employeeNumbersTbl; 

BEFORE STATEMENT 
IS 
BEGIN 
    -- Reset the internal employees table 
    g_employeeNumbers := employeeNumbersTbl(); 
END BEFORE STATEMENT; 

AFTER EACH ROW 
IS 
BEGIN 
    -- Store the updated employees 
    IF :new.employeeNumber <> :old.employeeNumber THEN   
    g_employeeNumbers.EXTEND; 
    g_employeeNumbers(g_employeeNumbers.LAST).oldEmployeeNumber := :old.employeeNumber; 
    g_employeeNumbers(g_employeeNumbers.LAST).newEmployeeNumber := :new.employeeNumber; 
    END IF; 
END AFTER EACH ROW; 

AFTER STATEMENT 
IS 
BEGIN 
    -- Now update the child tables 
    FORALL l_index IN 1..g_employeeNumbers.COUNT 
    UPDATE employees 
    SET assignTo = g_employeeNumbers(l_index).newEmployeeNumber 
    WHERE assignTo = g_employeeNumbers(l_index).oldEmployeeNumber; 
    FORALL l_index IN 1..g_employeeNumbers.COUNT 
    UPDATE customers 
    SET salesRepEmployeeNumber = g_employeeNumbers(l_index).newEmployeeNumber 
    WHERE salesRepEmployeeNumber = g_employeeNumbers(l_index).oldEmployeeNumber; 
END AFTER STATEMENT; 

END; 

編輯拆分成單獨的觸發器

此外，您將需要進行外鍵約束參考此表推遲例如

CREATE TABLE employees 
    (employeeNumber NUMBER  NOT NULL 
    ,lastName  VARCHAR2(30) NOT NULL 
    ,firstName  VARCHAR2(30) NOT NULL 
    ,email   VARCHAR2(50) NOT NULL 
    ,officeCode  VARCHAR2(10) NOT NULL 
    ,assignTo  NUMBER DEFAULT NULL 
    ,jobTitle  VARCHAR2(100) NOT NULL 
    ,PRIMARY KEY (employeeNumber) 
    ,FOREIGN KEY (officeCode) 
    REFERENCES offices (officeCode) 
    ,FOREIGN KEY (assignTo) 
    REFERENCES employees (employeeNumber) 
    DEFERRABLE 
    INITIALLY DEFERRED 
) 

和

CREATE TABLE customers 
    (customerNumber   NUMBER  NOT NULL 
    ,customerName   VARCHAR2(50) NOT NULL 
    ,phone     VARCHAR2(20) NOT NULL 
    ,address    VARCHAR2(70) NOT NULL 
    ,city     VARCHAR2(50) NOT NULL 
    ,postalCode    VARCHAR2(15) NOT NULL 
    ,country    VARCHAR2(40) NOT NULL 
    ,salesRepEmployeeNumber NUMBER DEFAULT NULL 
    ,PRIMARY KEY (customerNumber) 
    ,FOREIGN KEY (salesRepEmployeeNumber) 
    REFERENCES employees (employeeNumber) 
    DEFERRABLE 
    INITIALLY DEFERRED 
) 

注：如果違反約束，這將個別DML語句後不會導致錯誤的COMMIT。

Answer 2

您可以在以下方式重新編寫上述觸發，以避免問題：

create or replace trigger employees_update 
before update of employeeNumber on employees 
for each row 
begin 
emp_upd_trg_proc(:new.employeeNumber,:old.employeeNumber); 
update customers set 
salesRepEmployeeNumber = :new.employeeNumber 
where salesRepEmployeeNumber = :old.employeeNumber; 
end; 
/

create or replace procedure emp_upd_trg_proc 
(new number, old number) 
is 
pragma autonomous_transaction; 
begin 
update employees 
set 
assignTo = new 
where assignTo = old; 
commit; 
end; 

/