<commit_before># Database Management

## Context

- Database Fundamentals
  - Introduction
  - Relational Model
- Glossary

## Introduction

Database system has four components:
- Users
- Database application
- Database management system (DBMS)
- Database

## The Relational Model.

The characteristics of a relation:
- Rows contain data about entity
- Columns contain data about attributes of the entity
- Cells of the table holds a single value.
- All entries in a column are of the same kind
- Each column has a unique name
- The order of the column is unimportant
- The order of the rows is unimportant
- No two rows may hold identical sets of data values

Example of the **relation structure**:

    TABLE_NAME(Column1, Column2, Column3...., LastColumn)

Equivalent Sets of terms

```shell
    Table    | Row    | Column
    ---------|--------|----------
    File     | Record | Field
    ---------|--------|----------
    Relation | Tuple  | Attribute
```

## Glossary

**.NET Framework (.NET)** Microsoft’s comprehensive application development platform. It includes such components as ADO.NET and ASP.NET.

`<?php and ?>` The symbols used to indicate blocks of PHP code in Web pages.

**ACID transaction** A transaction that is *atomic*, *consistent*, *isolated*, and *durable*. An atomic transaction is one in which a set of database changes are committed as a unit; either all of them are completed or none of them are. A consistent transaction is one in which all actions are taken against rows in the same logical state. An isolated transaction is one that is protected from changes by other users. A durable transaction is one that, once committed to a database, is permanent regardless of subsequent failure. There are different levels of consistency and isolation. See transaction-level consistency and statement-level consistency. See also transaction isolation level.

**Database schema** A complete logical view of a database. It isa design on which a database and its associated applications are build.
<commit_msg>Update database.md<commit_after># Database Management

## Context

- Database Fundamentals
  - Introduction
  - Relational Model
- Glossary

## Introduction

Database system has four components:
- Users
- Database application
- Database management system (DBMS)
- Database

## The Relational Model

The characteristics of a relation:
- Rows contain data about entity
- Columns contain data about attributes of the entity
- Cells of the table holds a single value.
- All entries in a column are of the same kind
- Each column has a unique name
- The order of the column is unimportant
- The order of the rows is unimportant
- No two rows may hold identical sets of data values

Example of the **relation structure**:

    TABLE_NAME(Column1, Column2, Column3...., LastColumn)

Equivalent Sets of terms

```shell
    Table    | Row    | Column
    ---------|--------|----------
    File     | Record | Field
    ---------|--------|----------
    Relation | Tuple  | Attribute
```

## Glossary

**.NET Framework (.NET)** Microsoft’s comprehensive application development platform. It includes such components as ADO.NET and ASP.NET.

`<?php and ?>` The symbols used to indicate blocks of PHP code in Web pages.

**ACID transaction** A transaction that is *atomic*, *consistent*, *isolated*, and *durable*. An atomic transaction is one in which a set of database changes are committed as a unit; either all of them are completed or none of them are. A consistent transaction is one in which all actions are taken against rows in the same logical state. An isolated transaction is one that is protected from changes by other users. A durable transaction is one that, once committed to a database, is permanent regardless of subsequent failure. There are different levels of consistency and isolation. See transaction-level consistency and statement-level consistency. See also transaction isolation level.

**Database schema** A complete logical view of a database. It isa design on which a database and its associated applications are build.

** Active Server Pages (ASP)** A combination of HTML and scripting language statements. Any statement included in <% . . . %> is processed on the server. Used with Internet Information Server (IIS).

**Active Data Objects (ADO)** An implementation of OLE DB that is accessible via object- and non-object-oriented languages. It is used primarily as a scripting-language (JScript, VBScript) interface to OLE DB.

**ADO.NET** A data access technology that is part of Microsoft’s .NET initiative. ADO.NET provides the capabilities of ADO, but with a different object structure. ADO.NET also includes new capabilities for the processing of datasets.

**After-image** A record of a database entity (normally a row or a page) after a change. Used in recovery to perform rollforward.

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