How To create ORACLE Sequence to Populate Dimension Table based off another table - sql

Question

EDIT: I revised my original question for clarity. Hopefully this helps explain what I'm trying to accomplish more clearly.
I have a standard SQL table VEHICLES and I changed its name to OLTP_VEHICLES with a RENAME statement.
I created a new VEHICLES table as a dimension table that is the "beginning" of my star schema for this DB.
I now need to accomplish the following:
"For the vehicleCode primary key column, use an Oracle Sequence to populate the values. For the vehicleDescription column, use a concatenated combination of vehicleMake and vehicleModel from the OLTP_VEHICLES table."
I need to accomplish this by using a PL/SQL block to populate the description column by selecting the vehicleMake and vehicleModel from the OLTP_VEHICLES table and then inserting the concatenated combination into the VEHICLES Dimension table, via a cursor in a loop.
With this instruction, I am totally baffled. I think where I was confusing you fine folks before was the fact that I was leaving out the "second part" involving the insertion of the vehicleMake and vehicleModel concatenation.
Does this help explain better what I'm after? If not, I'm deeply sorry. I'm so confused on this that I'm even having trouble explaining it. Thanks again for your assistance.
CREATE TABLE VEHICLES
(vehicleVIN VARCHAR(25) PRIMARY KEY,
vehicleType VARCHAR(10) NOT NULL CHECK (lower(vehicleType) IN ('compact', 'midsize', 'fullsize', 'suv', 'truck')),
vehicleMake VARCHAR(15) NOT NULL,
vehicleModel VARCHAR(15) NOT NULL,
vehicleWhereFrom VARCHAR(20) NOT NULL CHECK (lower(vehicleWhereFrom) IN ('maryland','virginia','washington, d.c.')),
vehicleWholesaleCost DECIMAL(9,2) NOT NULL,
vehicleTradeID INT);
INSERT INTO VEHICLES
(vehicleVIN,vehicleType,vehicleMake,vehicleModel,vehicleWhereFrom,vehicleWholesaleCost,vehicleTradeID)
VALUES
('147258HHE91K3RT','compact','chevrolet','spark','Maryland',20583.00,NULL);
INSERT INTO VEHICLES
(vehicleVIN,vehicleType,vehicleMake,vehicleModel,vehicleWhereFrom,vehicleWholesaleCost,vehicleTradeID)
VALUES
('789456ERT0923RFB6','Midsize','ford','Taurus','washington, d.c.',25897.22,1);
INSERT INTO VEHICLES
(vehicleVIN,vehicleType,vehicleMake,vehicleModel,vehicleWhereFrom,vehicleWholesaleCost,vehicleTradeID)
VALUES
('1234567890QWERTYUIOP','fullsize','Lincoln','towncar','Virginia',44222.10,NULL);
INSERT INTO VEHICLES
(vehicleVIN,vehicleType,vehicleMake,vehicleModel,vehicleWhereFrom,vehicleWholesaleCost,vehicleTradeID)
VALUES
('WER234109TEO458GZ','SUV','Chevrolet','suburban','Maryland',52789.00,2);
ALTER TABLE VEHICLES RENAME TO OLTP_VEHICLES;
CREATE TABLE VEHICLES
(vehicleCode VARCHAR(25) PRIMARY KEY,
vehicleDescription VARCHAR(50) NOT NULL);
I also put this into SQL Fiddle if anyone wants to test something: http://sqlfiddle.com/#!4/2de3ae
Thanks!

Answer 1

Finally figured it out, after lots of research, trial and error, and of course, help from #MatBailie. Here's the solution I was after:
--Oracle sequence to populate primary key values in VEHICLES dimension table
DROP SEQUENCE SEQ_VEHICLES;
CREATE SEQUENCE SEQ_VEHICLES START WITH 1 INCREMENT BY 1;
CREATE OR REPLACE TRIGGER VEHICLES_PK
BEFORE INSERT ON VEHICLES FOR EACH ROW
BEGIN
SELECT SEQ_VEHICLES.NEXTVAL INTO :new.vehicleCode FROM DUAL;
END;
/
--PL/SQL Block to populate the description column via a cursor in a loop w/concatenation
DECLARE
CURSOR vehDesCur IS
SELECT LOWER(vehicleMake) || ' ' || LOWER(vehicleModel) AS vehicleDescription
FROM OLTP_VEHICLES;
BEGIN
FOR oltp_data IN vehDesCur
LOOP
INSERT INTO VEHICLES (vehicleDescription)
SELECT oltp_data.vehicleDescription
FROM dual
WHERE NOT EXISTS
(SELECT *
FROM VEHICLES v
WHERE v.vehicleDescription = oltp_data.vehicleDescription);
END LOOP;
END;
/