Require sum value of one table to be inserted into another table column

Question

Hi
I have a table which contains a list of parts and their prices required for an assembly.
I am trying to calculate the total from this part lists and put into the total price column for the assembly (another table column).
My method was to calculate the total in a page process ( eg, once all parts in the assembly have been entered the page process calculates the total price (the sum of the part prices at that time) and puts the result (total) in the assembly total column)
In the process I capture the total using either
SELECT SUM(TOTAL_COST) Total INTO B from CC_REQ_BOM WHERE RID = :P5_RID;
or
SELECT SUM(TOTAL_COST) INTO B from CC_REQ_BOM WHERE RID = :P5_RID;
Both the above sql statements are allowed ( one with alias and one without alais) by the page process but they dont seem to be working as no total is returned to the table when the page process is run.
to insert the calculation(variable B) into the required table I have used
INSERT INTO CC_REQ(TOTAL_COST)
VALUES(B);
I have used this method a few times with no problems for standard sql statements but this is the first time I have used it with the sum SQL function. For some reason it doesn't seem to like the SUM function even though the code below works in SQL Command window.
SELECT SUM(TOTAL_COST) from CC_REQ_BOM WHERE RID = :P5_RID;
Any help welcome.
PGJ

Answer 1

Hi
In that case, I would do something like this then...
CREATE TABLE crt_crates
(ccr_id   INTEGER        CONSTRAINT ccr_pk PRIMARY KEY,
ccr_name VARCHAR2(4000) CONSTRAINT ccr_nam_nn NOT NULL);
CREATE TABLE crt_requests
(cre_id        INTEGER        CONSTRAINT cre_pk PRIMARY KEY,
cre_reference VARCHAR2(4000) CONSTRAINT cre_ref_nn NOT NULL,
--I've skipped the requester as this would probably refernce a different table
--I've skipped request details as it's not necessary for this example
cre_ccr_id    INTEGER        CONSTRAINT cre_ccr_fk REFERENCES crt_crates);
CREATE TABLE crt_materials
(cma_id   INTEGER        CONSTRAINT cma_pk PRIMARY KEY,
cma_name VARCHAR2(4000) CONSTRAINT cma_nam_nn NOT NULL,
cma_cost NUMBER(12,2)   CONSTRAINT cma_cos_nn NOT NULL);
CREATE TABLE crt_crate_bom
(ccb_id       INTEGER CONSTRAINT ccb_pk PRIMARY KEY,
ccb_ccr_id   INTEGER CONSTRAINT ccb_ccr_fk REFERENCES crt_crates,
ccb_cma_id   INTEGER CONSTRAINT ccb_cma_fk REFERENCES crt_materials,
ccb_quantity INTEGER DEFAULT 1 CONSTRAINT ccb_qua_nn NOT NULL);
INSERT INTO crt_crates
VALUES(1, 'Crate 1');
INSERT INTO crt_requests
VALUES(1,'Request 1',1);
INSERT INTO crt_materials
VALUES(1,'Material 1', 1000);
INSERT INTO crt_materials
VALUES(2,'Material 2', 500);
INSERT INTO crt_crate_bom
VALUES(1,1,1,5);
INSERT INTO crt_crate_bom
VALUES(2,1,2,3);
COMMIT;
--So crate cost totals would be...
SELECT cre_reference              request,
       ccr_name                   crate,
       SUM(cma_cost*ccb_quantity) crate_cost
FROM   crt_requests,
       crt_crates,
       crt_materials,
       crt_crate_bom
WHERE  cre_ccr_id = ccr_id
AND    ccb_ccr_id = ccr_id
AND    ccb_cma_id = cma_id
GROUP BY cre_reference,
         ccr_name;
--And request cost totals would be...
SELECT cre_reference              request,
       SUM(cma_cost*ccb_quantity) crate_cost
FROM   crt_requests,
       crt_crates,
       crt_materials,
       crt_crate_bom
WHERE  cre_ccr_id = ccr_id
AND    ccb_ccr_id = ccr_id
AND    ccb_cma_id = cma_id
GROUP BY cre_reference; Do you see what I mean - you don't store the derived values as they could get out of sync with the component parts that make then up. You derive them from the underlying data instead.
Hope this makes sense.
Cheers
Ben