DB Summary PDF

# Data Base - **What is Data Base?** Simply the previous arranged data using applications such as excel sheet or any other application. - **Consists of?** Groups of Tables, rows and columns that are connected by relationships. - **What is a data base management system?** It stands for DBMS, and help...

# Data Base - **What is Data Base?** Simply the previous arranged data using applications such as excel sheet or any other application. - **Consists of?** Groups of Tables, rows and columns that are connected by relationships. - **What is a data base management system?** It stands for DBMS, and helps manage the connection between end users, the DBMS itself, the DB app and the database. - **What are the components of a data base?** The end users, DB app, DBMS and the database itself. - **What is the difference between a field and a record?** A field is a column, and a record is a row. ## Introduction to SQL - SQL stands for Structured Query Language. - It is used to manage and manipulate Relational Database Management Systems. - SQL allows users to: - retrieve data - insert new data - update existing data - delete data. - **Why is SQL important?** It is a widely used language that allows users to efficiently manage and analyze large amounts of data. ## The Basics of SQL - **What are the building blocks of SQL?** - Databases and Tables - Understanding the structure of the database and its tables - Queries - Statements - Learning how to use SQL to interact with the database - **What are Data Manipulation operations, and how are they performed in SQL?** - Inserting - Updating - Deleting data - **How do you retrieve data in SQL?** By retrieving specific data from the database using `SELECT`. ## Basic SQL Commands - **SELECT:** Used to retrieve data from a database table and is the most commonly used SQL command. - **INSERT:** Used to add new rows of data to a table. - **UPDATE:** Used to modify existing data in a table. - **DELETE:** Used to remove rows of data from a table. - **Where clause**: Used to filter data based on a specified condition. - **Comparison operators:** Used in the where clause. They include: `>`, `<`, `=`, `<>`. - **Order by clause:** Used to sort retrieved data in ascending or descending order. - **Join operations:** Used to combine data from multiple tables using different types of joins. ## Getting Started with SQL 1. Setting up a database 2. Create a table 3. Inserting data 4. Running queries ## SQL categories - **Data Query language (DQL).** - **SELECT statement:** Used to select data from the database. - **SELECT DISTINCT:** Used to return only distinct unique values. - **Data Definition Language (DDL)** - **CREATE DB statement:** Used to create a new SQL database. - **DROP DB:** Used to delete SQL database. - **CREATE TABLE:** Used to create a new table in the database. - **DROP TABLE:** Used to delete a table in the database. - **Data Manipulation Language (DML)** - **INSERT INTO:** Used to insert new data into a table. - **UPDATE:** Used to update data. - **DELETE:** Used to delete data from a table. ## Commonly Used SQL Data Types - **Integer (INT):** Used for whole numbers - **Varchar**: Used for variable length characters. - **Date:** Used for date values. - **DateTime:** Used for date and time values. - **Boolean (BOOL):** Used for `True` or `False`.