Basic data types in the database

in the database - a format for storing information that may contain a specific range of values. When computer programs store values ​​in variables, each variable must be assigned a specific type. Some in the database include integers, floating point numbers, characters, strings, and arrays. They may also be more specific types: dates, timestamps, logical values ​​and varchar (variable character) formats.data types in the database

Types of data in the database

Some programming languages ​​require the programmer to determine the data type of a variable before assigning a value to it. Other languages ​​can automatically set the data type of a variable when source values ​​are entered into a variable. For example, if var1 is created with the value "1.25", then the variable will be created as a floating point data type. If it is assigned the value Hello world!, Then the string type is assigned. Most programming languages ​​allow each variable to store one type of setpoint.If the variable value is already set as an integer, the assignment of string data may result in the information being converted to an integer format.

Types of setpoints are also used by database applications. Field types in a database often require the entry of well-defined values. For example, a company record for an employee might use the string type for the person's first and last name. The date of hiring an employee will be stored in a date format, and his salary can be saved as a whole. By storing the same types of database objects in multiple records, applications can easily search, sort, and compare fields.database field types

Table

A table is a data structure that organizes information into rows and columns. It can be used both for storage and for displaying values ​​in a structured format. Databases store content in tables so that you can quickly access information from specific rows. Sites often use them to display multiple lines on a page.

The main type of databases often contain several tables, each of which is designed for a specific purpose.For example, a company's information base may contain separate tables for employees, customers, and suppliers. Each of them can include its own set of fields, based on the data that should be stored in it. In the infobase tables, each field is considered a column, and each record is a row. A specific value can be obtained by requesting information from a separate column and row.database structure types

Application tables

Web sites often use tables to display data in a structured format. HTML has a <table> tag, as well as <tr> and <td> tags for specifying rows and columns. Because many tables use the top row for header information, HTML also supports the <th> tag, which is used to define cells in the header row. If there is a table on a webpage, large amounts of data can be displayed in a readable format. At the initial stage of development, HTML tables were used to build a general layout of web pages. However, cascading style sheets (CSS) over time replaced this tool and became the preferred tool for designing layouts.

Tables store and display data in a tabular format.Programs such as Microsoft Excel and Apple Numbers provide a grid or matrix of cells in which users can enter values. Each cell is defined by a pair of rows or columns, such as A3, it refers to a cell in the first column and the third row of the table. By formatting data, spreadsheet applications provide an easy way to enter and share information.

Database

It is a structure in which organized information is stored. Most resources contain several tables, each of which includes a different field. For example, a company database may include tables for products, employees, and financial records. Each of them has different fields related to the information stored in them.

Almost all e-commerce sites use different types of data in a database to store product inventory and customer information. These sites use a database management system (or DBMS), such as Microsoft Access, FileMaker Pro, or MySQL. Website content stored in it can be easily searched, sorted and updated. This flexibility is important for e-commerce resources and other dynamic sites.types of relational databases

History of development

Early databases were relatively flat, meaning that they were limited to simple rows and columns that looked like a regular spreadsheet. However, modern relational databases (DDB) allow you to access, update and search for information based on the ratio of values ​​stored in different tables. DDBs can also generate queries that process multiple databases. Although early databases could store only textual or numeric values, modern resources allow users to hold, including sound clips, images and video.

Types of relational databases

A relational database is a model of an information base that stores information in tables. The vast majority of resources used in modern applications are relational, so the terms “database” and “relational database” are often used interchangeably. Similarly, most database management systems (DBMS) are relational management systems (RDBMS). Other types of database models include flat file and hierarchical structures that are rarely used.

In computer science terminology, rows are sometimes called “tuples”, columns are “attributes,” and the tables themselves are called “relations.” A table can be represented as a matrix of rows and columns, where each intersection of a row and column contains a specific value.main database types

Organization of information in the RBD

Tables often include a primary key that provides a unique identifier for each type of structure in the database. A key can be assigned to a column (which requires a unique value for each row) or it can consist of several columns, which together form a unique combination of values. In any case, the primary key provides an efficient way to index values, which can be used to share them between tables. For example, a primary key value from one table may be assigned to a field in a row of another table. And numbers imported from other tables are called foreign keys.

The standard way to access information from a relational database is a SQL query, or a structured query. SQL queries can be used to create, modify and delete tables, as well as to select, insert and delete values ​​from existing ones.

Field

The field is a user interface element for data entry. Many software applications include text fields that allow you to enter information using the keyboard or touch screen. Websites often include form fields that a visitor can use to enter and send information.

In programs, the terms “field” and “text field” can be used interchangeably. For example, a processor may provide several formatting options, such as font size, line spacing, and page margins. Each parameter includes a text box in which the user can manually enter custom settings. Many applications also include a search box that allows you to search the contents of one or more documents.database object types

When visiting a website, this tool can provide a form that allows you to enter data, such as a billing address or registration information. Each single-line text field in a web form is called an "input box" and is defined by <input type = "text"> in HTML. Fields with more than one line are called "text areas", created using the <textarea> tag.There are also database field types that include two for entering a username and password. Most password fields are defined as <input type = "password">, which hides characters as they are entered.

Databases also include fields. Each row or “record” in a table can contain several elements. Table columns determine which windows are available in each row. Therefore, a specific combination of columns and rows (for example, Row: 101, Column: Name) defines a specific field. Individual parts can be searched and modified using standard SQL queries.

database model types

Line

A row is a horizontal group of values ​​within a table. Since they contain information from several columns, in databases each row of a table can be considered a record. For example, a window (or record) from the Employee table may contain the name, address, position, salary, and other employee information. When a database is queried, results are usually returned as an array of strings, which is similar to a group of records. Individual values ​​can be accessed by selecting a specific column (or field) in a row.

When displaying values ​​in a table format, the top row is often referred to as the “Table Header”. The cells in a row usually contain the name of each field.

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