About PHP And MYSQL(II)

So now we use the relational database management system (RDBMS) to store and manage large amounts of data. The so-called relational database is a database based on the relational model, which processes the data in the database with the help of mathematical concepts and methods such as set algebra.Click Here For More.

For RDBMS (relational database management system) features:

  1. Data are presented in tabular form Click Here For More.
  2. Record names for each action
  3. Data fields corresponding to each record name listed
  4. Many rows and columns form a form
  5. Several forms form a database

RDBMS terminologies

We have to understand some terminologies before learn about MySQL Click Here For More.

  • Database: A database is a collection of associated tables.
  • Data sheet: A table is a matrix of data. A table in a database looks like a simple spreadsheet.
  • Column: A column (data element) contains the same data such as postal code data.
  • Row: A row (equals to tuple, or record) is a set of related data such as data subscribed by a user.
  • Redundancy: Store twice as much data. Redundancy reduces performance but improves data security.
  • Primary key: Primary key is unique. A data table can contain only one primary key. You can use the primary key to query the data.
  • Foreign keys: Foreign keys are used to associate two tables.
  • Composite keys: Compound keys (combination keys) use multiple columns as an index key and are generally used for composite index.
  • Index: Use index to quickly access specific information in database tables. Index is a structure that sorts the values of one or more columns in a database table. It is similar to a book’s catalogue.Click Here For More.
  • Reference Integrity: Reference integrity requires that nonexistent entities are not allowed to be referenced in the relationship. The entity integrity is the necessary constraint condition for relational model.

Leave a Reply

Your email address will not be published. Required fields are marked *