Database:
- Database is a collection of data in a format that can be easily accessed(digital).
- A software application used to manage our db is called database management system
Types of databases:
- Relational - data stored in tables. Ex: MySQal, Oracle, Microsoft SQL Server, Postgre SQL
- Non relational(noSQL) - data not stored in tables. Ex: MongoDB
What is SQL:
- SQL is standard Structured Query Langugae used for storing, manipulating and retrieving data in databases.
- It is used to perform CRUD operation , Create, read, update and delete
RDBMS:
- RDBMS stands for Relational Database Management System.
- RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.
- The data in RDBMS is stored in database objects called tables.
A Table:
- A table is a collection of related data entries and it consists of columns and rows. For example, customers table.
- Every table is broken up into smaller entities called fields. The fields in the Customers table consist of CustomerID, CustomerName, ContactName, Address, City, PostalCode and Country.
- A field is a column in a table that is designed to maintain specific information about every record in the table.
- A record, also called a row, is each individual entry that exists in a table. A record is a horizontal entity in a table.
- A column is a vertical entity in a table that contains all information associated with a specific field in a table.
| CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
|---|---|---|---|---|---|---|
| 1 | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
| 2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
| 3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
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