Each value in the database has a datatype, which associates a set of properties with it – for example, a DATE column can accept dates only, not strings or numbers. Datatypes may be built-in or user-defined.
Are you data modeling for a custom OLTP application starting from scratch, with business requirements as the only initial input?
No matter what the size, domain or location of your project, the following lessons will help to ensure that your physical data modeling process is smooth and that you end up with a database design that is accurate, usable and scalable.
A collection is a list of elements of the same type. Each element in the list has a unique position number or label, called the "subscript".
To give a logical analogy, consider a list of colors = {red, blue, green, yellow}. This list has four elements, all names of colors. There is a unique position of each element in the list. If we number the positions sequentially starting from one, we could say:
color[1] = red, color[2] = blue, and so on.
Here, color is the name of the collection, and the numbers within [] are the subscripts.
PL/SQL has three collection types. In this article, we’ll look at a chart for comparing the three, their advantages and limitations, and which one to use for your needs.
The Oracle database does not have the BOOLEAN datatype. No direct way to represent that a column like IS_ACTIVE on table ITEMS is TRUE or FALSE.
The good news is that there are simple workarounds to the situation.
Oracle has three datatypes to store strings. – CHAR, VARCHAR and VARCHAR2. How do they differ from each other? When should you use which?
Let’s find out the answers in this article.