The foundation of WellRep is formed by the Advantage relational database in which all the data is stored. The database is formed by a Data Dictionary which contains definitions of all tables with the individual data tables as separate data files.
The term relational database refers to the way in which data is separated into individual tables that are related on a key value.
Consider the following example table:
|
WELLDATA |
BHA DATA |
||||
|
Well name |
Operator |
… |
BHA No. |
Hole Size |
… |
|
Well #1 |
Operator |
… |
1 |
17-1/2” |
… |
|
Well #1 |
Operator |
… |
2 |
12-1/4” |
… |
|
Well #1 |
Operator |
… |
3 |
8-1/2” |
… |
|
… |
… |
… |
… |
… |
… |
|
Well #2 |
Operator |
… |
1 |
17-1/2” |
… |
|
Well #2 |
Operator |
… |
2 |
17-1/2” |
… |
|
Well #2 |
Operator |
… |
3 |
12-1/4” |
… |
|
… |
… |
… |
… |
… |
… |
This table can be logically split into two separate tables:
|
WELL DATA |
|
BHA DATA |
||||||
|
ID |
Well name |
Operator |
|
BHA ID |
Well ID |
BHA No. |
Hole Size |
… |
|
1 |
Well #1 |
Operator |
|
1 |
1 |
1 |
17-1/2” |
1 |
|
2 |
Well #2 |
Operator |
|
2 |
1 |
2 |
12-1/4” |
2 |
|
… |
… |
… |
|
3 |
1 |
3 |
8-1/2” |
3 |
|
|
|
|
|
4 |
2 |
1 |
17-1/2” |
… |
|
|
|
|
|
5 |
2 |
2 |
17-1/2” |
… |
|
|
|
|
|
6 |
2 |
3 |
12-1/4” |
… |
|
|
|
|
|
… |
… |
… |
… |
… |
In the first table, each individual BHA record contains all well information. Not only does this consume additional space in the database (thereby hard-disk space), but each piece of well information is copied several times. This leads to the requirement to update several records as well information changes. This is cumbersome and will ultimately lead to inconsistent and possibly corrupt data.
Once the table is split into two separate tables, each record in each table is given a unique (within the table) ID number. The child table (BHA) is also labeled with the ID of the corresponding parent record (well). This is indicated by the colors used. This process minimizes space used, enhances data consistency and promotes the “once in – many out” principle.
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