Relational Database Model

Comparison and comparison of relational database models and object-oriented models Relational database models are based on tables or relationships. In this model, the physical implementation of the database is abstracted from the user. The user queries the database using an advanced query language such as SQL. A relationship consists of a column with a header indicating the attribute that the column represents. The table has key fields that you can use to identify unique records. The key associates the tables with each other.

The basic mathematical concept of the relational database model is a set - theoretic relationship, which is a subset of the Cartesian product of the domain list. A domain is a series of values. A relationship is any subset of the Cartesian product of one or more domains. Members of a relationship are called tuples. Relational databases treat relationships as tables. The prologue view of a relationship is a series of views of named tuples. For example, in Prolog format, the following are some unexpected entries in the city-state-population relationship.

The most common database model in a general purpose database is a relational model, more precisely expressed in SQL language. The process of creating a logical database design using this model uses a method approach called normalization. The purpose of normalization is to ensure that each basic "fact" is recorded in one place so that inserts, updates, and deletes can automatically maintain consistency. The final stage of database design is to make decisions that affect performance, scalability, recovery, security, etc., depending on the specific DBMS. This is often referred to as a physical database design and the output is a physical data model. The main goal at this stage is data independence. In other words, decisions aimed at optimizing performance should not be visible to end users and applications. There are two types of data independent, physical data independent and logical data independent.

The relational database model has many advantages such as built-in multi-level integrity independent of the logical data and physical data of the database application, data consistency and accuracy, and simple data acquisition. 2 Traditional databases are organized by fields, records, and files. A field is a single piece of information, a record is a series of fields, and a file is a collection of records. The table is the data arranged in rows and columns. For example, the spreadsheet is a table. A table (called Relationship in relational database theory) is the main structure of a relational database. It consists of fields and records, the order of which is absolutely immaterial. A table always represents a single specific topic and can be an object or an event. Relational databases are very powerful because there is little need to assume how the data is related or how to extract the data from the database. 3