Database Theory

I have been reading a study guide to pass Oracle certification test SQL and PL/SQL. Having finished the book, I am going back over the things I have learned. Chapter 1 starts out with basic relational database theory. It then beings to show how this translates into the Oracle database.

There is logical database modeling which is is at a high level of abstraction. Real life items such as nouns are entities. These entities have characteristics called attributes. The entities are related by relationships.

When you get into the physical design of the database, entities become database tables. Attributes become columns in the tables. And relationships between the entities become table constraints. Instances of the entity are records in the table.

Next the chapter went on to some Oracle database basics. There are many native database types. One of them is the NUMBER, where you can specify the maximum total digits in the value, and the precision which is the number of digits after the decimal point.

I will do another post in the future with more Oracle basics. Some topics I might hit are ROWID, UNION, and SPOOL.