What Is Relational Database
What Is Relational Database
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What Is Relational Database
In 1970, Dr. E. F. Codd of IBM’s research laboratory published a paper titled “A Relational Model of Data for Large Shared Data Banks” that proposed that data be represented as sets of tables. Relational database is a type of database that stores and provides access to data table that are related to one another data table.
A system used to maintain relational databases is a relational database management system (RDBMS).
Each table in a relational database includes information that uniquely identifies a row in that table (known as the primary key), along with additional information needed to describe the entity completely.
Every database server provides a mechanism for generating unique sets of numbers to use as primary key values, so you won’t need to worry about keeping track of what numbers have been assigned.
A primary key consisting of two or more columns is known as a compound key.
There could easily be two or more people with the same first and last names that have accounts at the bank. Therefore, we chose to include the emp_id column in the customer table specifically for use as a primary key column.
Selecting first name and last name as the primary key would be referred to as a natural key, whereas the choice of emp_id would be referred to as a surrogate key.
A foreign key (FK) is a column or combination of columns that is used to establish and enforce a link between the data in two tables to control the data that can be stored in the foreign key table.
Also, It is not proper for a single column to contain multiple pieces of information, such as a name column that contains both a person’s first and last names, or an address column that contains street, city, state, and zip code information. The process of refining a database design to ensure that each independent piece of information is in only one place is known as normalization.
All database elements created via SQL schema statements are stored in a special set of tables called the data dictionary. This “data about the database” is known collectively as metadata.