How to get this report format out ?

Question

Hello all experts,
Sample table creations like the following. Note checkno under xcheck table is not unique. Have tried pivotting the xcheck table then link pivoted xcechk with xcert using certno and invno but this willl end up getting duplicate records. Can u please help ? Basically I am stuck at how to get that vendor name out on the report
create table xcert(
certseq number primary key,
certno varchar2(5) not null,
vendor varchar2(25));
create table xcheck(
checkseq number primary key,
checkno varchar2(8) not null,
invno varchar2(100);
Xcert Data
certseq certno     vendor
1     C1001     BP GAS
2     C1002     BUG PEST CONTROL
3     C1003     BP GAS
4     C1004     BP GAS
5     C1005     WILLIES BESTxcheck Data
checkseq     checkno          invno
1          EF500001     C1001,C1003,C1004
2          EF500002     C1002
3          EF500002     C1005Looking for a following report format
checkno          invno               vendor
EF500001     C1001,C1003,C1004     BP GAS
EF500002     C1002               BUG PEST CONTROL
EF500002     C1005               WILLIES BEST      Thank you
Munshar

Answer 1

Hi, Munshar,
MunSharmi wrote:
Frank,
"I don't see why you would need another column. What would you need to store, or retrieve, that a table like this wouldn't allow?
Notice my orignal xcheck table data plus a check date column
{code}
checkseq     checkno          invno               checkdate
1          EF500001     C1001,C1003,C1004     11/01/2010
2          EF500002     C1002               12/10/2010          
3          EF500002     C1005               01/01/2011
{code}Sure, if you have other data that you haven't mentioned yet, then you need other columns, and maybe even other tables, to store that data.
Talking about this would be a lot easier if you described what you were trying to model in these tables, and what the different entities are.
after nomalization
{code}
seq(PK)     checkseq     checkno          invno               checkdate
1     1          EF500001     C1001               11/01/2010
2     1          EF500001     C1003               11/01/2010
3     1          EF500001     C1004               11/01/2010
4     2          EF500002     C1002               12/10/2010          
5     3          EF500002     C1005               01/01/2011
{code}What do checkseq and checkdate represent? What is the realtionship between them? If there is another row with checkseq=3, will it necessarily have checkdate=01/01/2011? If there is another row with checkdate=01/01/2011, will it necessarily have checkseq=3?
Shouldn't I need to have the extra seq(PK), then use check seq to group the data report to meet users' target format ? Please adviseIt depends on what your entities are. If you explain that, then perhaps I can give some advice about how to model them.
In general, every type of entity requires a separate table. It looks like xcert represents one kind of entity, uniquely identified by certno. I assume there is some other kind of entity, uniquely identified by checkno, and that you have a table for that which you haven't needed to show in this thread.
Are you saying that there's some other entity, that is uniquely identified by checkseq? If so, it probably needs a table of it's own.
Every table should have a primary key. I had assumed that checkseq only served as the primary key of the xcheck table. If it serves some other purpose, then yes, you would need another column.
Many-to-many relationships usually require a separate table. I was guessing that xcheck was intended to record a many-to-many realtionship between xcert and some other table. Guessing is not always the best way to solve problems. I think it would be better if you explained what you want to do, rather than have me guess at it.
So far, what you've shown is analagous to an order entry system. One kind of entity is customer, another is supplier. Say you're running a company that sells products from many suppliers to many customers. There is a many-to-many relationship between customers and suppliers. Any customer may buy from many suppliers; any supllier may sell to many cutomers. You may have an orders table that keeps track of that many-to-many relationship. You may also have another entity, salesman, that also has many-to-many relationships with customers and suppliers. Depending on what exactly you consider an "order", there are lots of different ways to model this. Can a single order involve many customers? Can a single order involve many suppliers? Can a single order involve many salesmen? If an order always involves one customer buying from one supplier using one salesman, then you may only need four tables. If the situation is more complicated, then you may need more tables.