meaning of database manager

1. database manager The part of the database management system DBMS that handles the organisation, storage and retrieval of the data. A database manager may work with traditional programming languages, such as COBOL and BASIC, or may work only with its proprietary programming language. The terms database manager and database management system are used interchangeably. A database manager links two or more files together and is the foundation for developing routine business systems. Contrast with file manager, which works with only one file at a time and is typically used interactively on a personal computer for managing personal, independent files, such as name and address lists. database normalisation A series of steps followed to obtain a database design that allows for efficient access and storage of data in a relational database. These steps reduce data redundancy and the chances of data becoming inconsistent. A table in a relational database is said to be in normal form if it satisfies certain constraints. Codds original work defined three such forms but there are now five generally accepted steps of normalisation. The output of the first step is called First Normal Form 1NF, the output of the second step is Second Normal Form 2NF, etc. First Normal Form eliminates repeating groups by putting each into a separate table and connecting them with a one-to-many relationship. Second Normal Form eliminates functional dependencies on a partial key by putting the fields in a separate table from those that are dependent on the whole key. Third Normal Form eliminates functional dependencies on non-key fields by putting them in a separate table. At this stage, all non-key fields are dependent on the key, the whole key and nothing but the key. Fourth Normal Form separates independent multi-valued facts stored in one table into separate tables. Fifth Normal Form breaks out data redundancy that is not covered by any of the previous normal forms. http://www. bkent. net/Doc/simple5. htm. [What about non-relational databases?]

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