Problems Creating a trigger using Oracle

问题

My question is:

A Trigger which automatically stores in a separate table called ‘ExcellentSale’ the Sales Agent name, car model and manufacturer name, each time the agreed price of a SalesTransaction is more than 20% of the car’s asking price. (Note: You need to create the ‘ExcellentSale’ table before implementing this trigger. To create the primary key, use a sequence that starts at 1 and increments by 1).

I am using theses tables

Manufacturer(manufacturerID, name, region)

Model(modelNo, name, type, previousModel, manufacturerID)

Car(VIN, dateAcquired, yearBuilt, purchasedPrice, askingPrice,
currentMileage, modelNo)

SalesAgent(agentID, name, DOB)

SalesTransaction(VIN, custID, agentID, dateOfSale, agreedPrice)

Here is my attempt

create sequence ggenerateKey
start with 1
increment by 1;
CREATE TABLE ExcellentSale(
recordNo NUMBER,
agentName VARCHAR2(20) NOT NULL,
modelName VARCHAR2(20) NOT NULL,
manufacturerName VARCHAR2(20) NOT NULL,
PRIMARY KEY(recordNo));
create or replace trigger AutoStore
before insert on SalesTransaction
for each row
declare
agentName varchar2(50);
modelName varchar2(50);
manufacturerName varchar2(50);
askingprice number;
agreedprice number;
begin
select sa.name, mo.name, mu.name, c.askingprice, st.agreedprice
into agentName, modelName, manufacturerName, askingprice, agreedprice
from manufacturer MU, Model MO, Car C, SalesAgent SA, SalesTransaction ST
where mu.manufacturerid = mo.manufacturerid
and st.vin = c.vin
AND c.vin = :new.vin
AND sa.agentID = :new.agentID;
IF :new.agreedPrice > (1.2 * askingPrice) THEN 
INSERT INTO ExcellentSale
VALUES
(ggenerateKey.nextval, agentName, modelName, manufacturerName);
END IF; 
end AutoStore;
/

The trigger compiles and when I try to test this I use these values that will be inserted into SalesTransaction, this should then fire the trigger but shows as an error.

insert into SalesTransaction
values
('2B7JB33R9CK683376', '1', '1', to_date('01-02-2013','dd-mm-yyyy'), 586000 );

The error shown is this

insert into SalesTransaction
            *
ERROR at line 1:
ORA-01403: no data found 
ORA-06512: at "JTLA.AUTOSTORE", line 8 
ORA-04088: error during execution of trigger 'JTLA.AUTOSTORE'

回答1:

This error means that your select statement with "into" clause produces no rows. To avoid this error, I usualy use aggregate function MAX() on each column, it garante 1 row result set, generates null values in case of 'no matching rows', and no exception rised

来源：https://stackoverflow.com/questions/30455567/problems-creating-a-trigger-using-oracle

标签

Oracle

plsql

database-trigger