Relational Database Theory
In 1970 a
mathematician Edgar F. Codd, published the concept that would allow people to
access information from databases without having to know how they are structured.
Common relational database software are Microsoft Access and Oracle.
To
understand the basic concepts there are a few key terms to identify. A database
can be defined as one that contains one or more tables of information. The rows
within a table are referred to as records
and the columns are referred to as
fields or attributes. A
relational database requires two or more related tables. Sometimes in order to
increase efficiency and reduce error normalizing
data is required. This involves dividing information into multiple tables that
are organized differently so that there is not redundant information. Primary keys are values within a field
that are composed of all unique values. For instance if a table has fields: student
identification number, age, and degree. The primary key in this case is student
identification number because there is not repeated value, each student has a
unique identification number. When normalizing data the tables are structured
as either parent, child, or orphan. When two tables have an unequal
relationship, the independent one is referred to as the parent and the dependent one is the called the child. However, if there a record within the child table that does
not appear in the parent table, that record is called an orphan. The number of records in one table that can be related to
the records of another is table is identified as cardinality.
The major advantage and use of relational models is
its uniformity. All value stored in a table is organized to comply with the
same structure. That is each record (row) are formatted the exact same.
However, the fields can be unique to each primary key. Additionally, data is
only stored once and allows for more efficient storage of information. It also
allows for better security since data can be organized into multiple tables.
This separation allows one to limit access to certain tables.
Works Cited
[1] http://www-03.ibm.com/ibm/history/ibm100/us/en/icons/reldb/
Hello Janet,
ReplyDeleteAfter having researched SQL it is interesting to see how relational database theory ties in with SQL. Having such strict, but necessary limitations to the establishment of databases 46 years ago is interesting to look at when technology was much more limited. To see how far we've progressed in terms of the shear size and complexity of databases is interesting.
Hi Janet! This was a well thought out explanation on relational database theory. It's crazy that relational databases have been around since the 1980's and are still going strong. The idea of primary keys really interesting in my opinion. I feel like there are only a finite amount of primary keys that could be used in a database, so what happens when a database has too much data to keep uniquely identifying? Great post!
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ReplyDeleteHi Janet, I like your post! The structure is very clear and logic. I really can’t believe today people still using this database theory for bank accounts, using credit cards and buying thing online, etc. I think the advantages you listed above is why this database can keep alive for such a long time.
ReplyDeleteJanet, your post helped me further understand rational databases. This a confusing topic if not explained in a simple manner. I believe that having the information as tables is much easier to understand, also allowing the information to be easily manipulated and extracted by the operator. Data can also can be manages, updated and combined easily by using the SQL, without having knowledge of the SQL, making it practical for the user.
ReplyDeleteI like your succinct summary of relational database theory, especially that you included definitions of key terms. You mention common database software, Oracle and Access; what are the major differences between the two programs, or are they largely the same? Is one easier to navigate, or includes more features than the other?
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