Several cases must be considered. If the deletion reduces the number of keys in a node below the minimum degree of the tree, this violation must be corrected by combining several nodes and possibly reducing the height of the tree. If the key has children, the children must be rearranged. A database is a collection of data organized in a fashion that facilitates updating, retrieving, and managing the data. The data can consist of anything, including, but not limited to names, addresses, pictures, and numbers.
Databases are commonplace and are used everyday.
For example, an airline reservation system might maintain a database of available flights, customers, and tickets issued. A teacher might maintain a database of student names and grades. Because computers excel at quickly and accurately manipulating, storing, and retrieving data, databases are often maintained electronically using a database management system . Database management systems are essential components of many everyday business operations. It is not uncommon for a database to contain millions of records requiring many gigabytes of storage.