Databases can have various objects some of which are tables, queries, forms or views, and reports objects. Each of these has fields or columns. Describe the function of each of these objects and how fields or columns differ from one object to another. Describe the different relationships that exist between tables, and provide real-world examples of how each of these might be used.

Databases can have various objects some of which are tables, queries, forms or views, and reports objects. Each of these has fields or columns. Describe the function of each of these objects and how fields or columns differ from one object to another.

--

Database Objects provide a number of advantages, including database independence, automatic connection handling, declarative referential integrity, multi-level validations, security, and much more.

By using Database Objects in your application, you can take advantage of all of these capabilities without writing additional code.

Using database objects allows an application to avoid embedded SQL and it's maintenance difficulties and system dependencies. Applications simply interact with other Java objects, allowing the design of a system to be entirely object-oriented.

Database objects are built from the ground up to be database independent - they do not rely on the features of a specific underlying database to provide their functionality. This allows an application build using database objects to be ported from one database platform to another in literally moments, providing the potential for great scalability.

Describe the different relationships that exist between tables, and provide real-world examples of how each of these might be used.

- - relationship between tables can be foreign keys which are joined by various types of joins

A foreign key consists of one or more columns in a table whose value in one row uniquely identifies another row in the same or another table.

There are three types of relationships:

One-to-one: Both tables can have only one record on either side of the relationship. Each primary key value relates to only one (or no) record in the related table. They're like spouses%u2014you may or may not be married, but if you are, both you and your spouse have only one spouse. Most one-to-one relationships are forced by business rules and don't flow naturally from the data. In the absence of such a rule, you can usually combine both tables into one table without breaking any normalization rules.

One-to-many: The primary key table contains only one record that relates to none, one, or many records in the related table. This relationship is similar to the one between you and a parent. You have only one mother, but your mother may have several children.

Many-to-many: Each record in both tables can relate to any number of records (or no records) in the other table. For instance, if you have several siblings, so do your siblings (have many siblings). Many-to-many relationships require a third table, known as an associate or linking table, because relational systems can't directly accommodate the relationship.