Full SQL notes clearly and understandable to sql beginner level

Below are some clear and understandable notes for beginners to SQL (Structured Query Language):

Introduction to SQL:

SQL (Structured Query Language) is a programming language used to manage and manipulate relational databases.
It allows you to perform various operations on data, such as querying, inserting, updating, and deleting records in a database.

Basic SQL Commands:

SELECT column1, column2 FROM table_name;

2. INSERT: Used to add new records into a table.

INSERT INTO table_name (column1, column2) VALUES (value1, value2);

3.UPDATE: Used to modify existing records in a table.

UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;

4. DELETE: Used to remove records from a table.

DELETE FROM table_name WHERE condition;

Creating a Table:

To create a new table, use the CREATE TABLE statement with column names and data types

CREATE TABLE table_name (

    column1 datatype,

    column2 datatype,

...

);

Constraints:

Constraints are rules applied to columns to maintain data integrity. Some common constraints are:

NOT NULL: Ensures a column cannot have NULL values.
UNIQUE: Ensures each value in a column is unique.
PRIMARY KEY: A combination of NOT NULL and UNIQUE, used to identify a unique row in a table.
FOREIGN KEY: Establishes a link between two tables, referencing a primary key in another table.

Filtering Data:

You can use the WHERE clause to filter data based on certain conditions in a SELECT statement.

SELECT column1, column2 FROM table_name WHERE condition;

Sorting Data:

To sort the results of a SELECT statement, use the ORDER BY clause.

SELECT column1, column2 FROM table_name ORDER BY column1 ASC/DESC;

Joins:

Joins are used to combine data from multiple tables based on a related column. Common types of joins are:

INNER JOIN: Returns only the matching rows from both tables.
LEFT JOIN (or LEFT OUTER JOIN): Returns all the rows from the left table and matching rows from the right table.
RIGHT JOIN (or RIGHT OUTER JOIN): Returns all the rows from the right table and matching rows from the left table.
FULL JOIN (or FULL OUTER JOIN): Returns all the rows when there is a match in either the left or right table.

Grouping Data:

The GROUP BY clause is used to group rows that have the same values in one or more columns.

SELECT column1, COUNT(*) FROM table_name GROUP BY column1;

Aggregate Functions:

Aggregate functions perform calculations on grouped data. Common aggregate functions are:

Updating Multiple Records:

You can update multiple records at once using the WHERE clause in the UPDATE statement.

UPDATE table_name SET column1 = value1 WHERE condition;

Deleting Multiple Records:

You can delete multiple records at once using the WHERE clause in the DELETE statement.

DELETE FROM table_name WHERE condition;

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