DatabaseData base and its technology has played an important role along with the growth of computer use. The
database has been used in almost all areas where computers are used,
including business, engineering, health, law, education and so on.Said data base can be defined as a collection of related data. While the data word can be defined as a fact that was recorded or noted. For example the names, phone numbers, and addresses of people you know. You
may have to record this data in the address book, or you can store them
in floppy disks, using a personal computer and software such as dBASE
IV,Relational Database ConceptsThe principle of the relational model (relational model) was first introduced by Dr. EF Codd, in June 1970 in an article entitled "A Relational Model of Data for Large Shared Data Banks." In this article, Dr. Codd's relational model to explain the data base system.The models used are more popular at the time was hierarchical and network, or even simple flat file data stuctures. Relational
Database Management Systems (RDBMS) soon became very popular, mainly
because of the ease of use and flexibility of data structures.Furthermore,
many vendors have sprung up to support these systems such as Oracle,
which supports the RDBMS with a package for building applications and
products ready for use, as a total solution for the purposes of
development of information technology.
Relational Model ConceptsThe concept of the relational database model has some important definitions as follows:
Collection of objects or relations to store data
Collection of operators that perform an action against a relation to generate other relations
Relational database to support the integrity of the data so that data must be accurate and consistentExamples of the relation is a table. We can use SQL commands to display data from tables.Functions of Relational DatabaseRelational database has a utility function as follows:
Set the data storage
Controlling access to data
Support the process of displaying and manipulating data
Terms Relational DatabaseSome terms we need to understand about relational databases, among others:
Table: This is the basic storage structure of a relational data base, consisting of one or more columns (column) and zero or more rows (row).
Row (row): The line is a combination of column values in a table-for example, information about a department in the Department table. Line is often called the "record".
Column (column): This column describes the type of data in the table: for example, the name of the department in the Department table. Column is defined with the column names and data types along the length of certain data.
Field: Field is a meeting between the rows and columns. A field can contain data. If at any field there are no data, then the field is said to have a value of "null".
Primary key: primary key or primary key is a column or set of columns that uniquely distinguish between the lines with one another: for example, is the department code. Column with this category should not contain the value "null", and its value must be unique (different from the line with one another).
Foreign key: Foreign key or room key is a column or set of columns that refers to the primary key is the same table or another table. Foreign key is made to impose rules on the basis of data relationships. Data from the foreign key value must match the data values in the column of the table to which it refers or the value "null".
Relational Model ConceptsThe concept of the relational database model has some important definitions as follows:
Collection of objects or relations to store data
Collection of operators that perform an action against a relation to generate other relations
Relational database to support the integrity of the data so that data must be accurate and consistentExamples of the relation is a table. We can use SQL commands to display data from tables.Functions of Relational DatabaseRelational database has a utility function as follows:
Set the data storage
Controlling access to data
Support the process of displaying and manipulating data
Terms Relational DatabaseSome terms we need to understand about relational databases, among others:
Table: This is the basic storage structure of a relational data base, consisting of one or more columns (column) and zero or more rows (row).
Row (row): The line is a combination of column values in a table-for example, information about a department in the Department table. Line is often called the "record".
Column (column): This column describes the type of data in the table: for example, the name of the department in the Department table. Column is defined with the column names and data types along the length of certain data.
Field: Field is a meeting between the rows and columns. A field can contain data. If at any field there are no data, then the field is said to have a value of "null".
Primary key: primary key or primary key is a column or set of columns that uniquely distinguish between the lines with one another: for example, is the department code. Column with this category should not contain the value "null", and its value must be unique (different from the line with one another).
Foreign key: Foreign key or room key is a column or set of columns that refers to the primary key is the same table or another table. Foreign key is made to impose rules on the basis of data relationships. Data from the foreign key value must match the data values in the column of the table to which it refers or the value "null".
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