SQLQuery

Data Defination Language

Used for defining the few examples are CREATE, DROP, ALTER, TRUNCATE, RENAME

CREATE - Used for creating tables.

CREATE TABLE table_name (
    column1 data_type(size),
    column2 data_type(size),
    ...
);

DROP - Used to delete an entier table

DROP TABLE table_name

ALTER - Used for adding new columns, updating data types and deleting colummns.

ALTER TABLE table_name ADD column_name datatype;
ALTER TABLE table_name DROP COLUMN column_name;
ALTER TABLE table_name MODIFY COLUMN column_name datatype(size);

TRUNCATE - Delete all data inside the table

TRUNCATE TABLE table_name;

RENAME - Used for changing name of the existing column with other name.

RENAME TABLE old_table_name TO new_table_name;

Data Manipulation Language (DML)

DML Statements are used for performing queries on the data present in the database. Examples are INSERT, UPDATE, DELETE

INSERT Adding data to any table

INSERT INTO table_name 
    ( column1, column2, column3, ... )  
VALUES 
    ( value1, value2, value3, ... )

UPDATE - Update existing data based on WHERE condition, If WHERE is not passed then all the data might get effected.

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

DELETE - Removes data permenatly from the databases based on the condition present in the WHERE clause, If that is not present then entire data present in the table will be deleted.

DELETE FROM table_name WHERE condition;

Data Query Langauge (DQL)

DQL is used to perform operations on the data to fetch data, Mainly SELECT is used for fetching Based on the conditions passed on WHERE clause and ordering data from order by clause and using various other parameters.

SELECT 
    column1, column2, ... 
FROM 
    table_name
WHERE 
    condition...

DISTINCT - To get only unique data

    SELECT 
        DISTINCT column1, column2, ...
    FROM 
        table_name

ORDER BY - To order perticular data

    SELECT 
        column1, column2, ...
    FROM 
        table_name
    ORDER BY 
        column ASC|DESC;

GROUP BY and HAVING - To Group based on condition

    SELECT 
        column1, column2
    FROM 
        table_name
    GROUP BY 
        column1, column2;

    SELECT 
        column1, column2
    FROM 
        table_name
    GROUP BY 
        column1, column2
    HAVING 
        condition value;

JOIN - To join multiple tables we are using join operator

   SELECT 
       table1.column1, table2.column2...
   FROM table1
   (INNER | LEFT | RIGHT | FULL) JOIN table2
       ON table1.matching_column = table2.matching_column;

By USING

    SELECT 
        table1.column1, table2.column2...
    FROM table1
    (INNER | LEFT | RIGHT | FULL) JOIN table2
        USING matching_column;

INNER JOIN - Gives record matching condititions from both conditions
LEFT JOIN or LEFT OUTER JOIN - Gives all record from table1 and matching conditions from table2
RIGHT JOIN or RIGHT OUTER JOIN- Gives all record from table2 and matching conditions from table1
FULL JOINor FULL OUTER JOIN - Returns all the record from the table1 and table2
SELF JOIN - To Get record of one table using values of same table

    SELECT 
        a.column_name, b.column_name...
    FROM 
        table_name AS a, 
        table_name AS b
    WHERE 
        condition;

CARTESIAN JOIN - Same as above without where condition

    SELECT 
        a.column_name, b.column_name...
    FROM 
        table_name AS a, 
        table_name AS b

1001pranav/SQLQuery

SQLQuery

Data Defination Language

Data Manipulation Language (DML)

Data Query Langauge (DQL)