Notes.txt

Q1. What is MySQL ?
Ans. MySQL is a relation database management system (RDBMS) developed by Oracle that is based on structured query language (SQL).
Q2. What is database ?
Ans. A database is organized collection of structured information, or data.
Q3. What is DBMS ?
Ans. Database Management System (DBMS) are software systems used to store, retrieve, and run queries on data.
	C	==>	create
	R	==>	read
	U	==>	update
	D	==>	delete
Q4. How many types of DBMS ?
Ans. There are two types of DBMS :-
	a). Relational (SQL)
	b). Non-relational (No-SQL)
Q5. What is Relational database ?
Ans. A relational database is a collection of data items with pre-defined relationships between them, stored in the form of table, rows and columns.
	List of SQL Databases
	a). MySQL
	b). MariaDB
	c). Oracle
	d). postgreSQL
	e). MSSQL
Q6. How to install MySQL ?
Ans. Step to follow.....
	1). Install server
		MySQL community Server
	2). Install MySQL Workbench.
Q7. MySQL Shell work in command form
	command ==> 	cd bin folder path and enviroment set a user path
			mysql -u root -p
			then enter a password
			show databases; semi-colan mandatory
			create database db;
			use db; enter a database
			show databases;
Q8. How to create table in MySQL ?
Q9. What is a database table ?
Ans. Database table is collection of rows and columns that contains relational data.
Q10. Categories of Datatypes.
	a). String
	b). Numeric
	c). Date & Time
Q11. Create table syntax
Ans. CREATE TABLE table_name
	{
		column1 datatype,
		column1 datatype,
		column1 datatype,
		.........
	};
Q12. Create users Paper schemas
	id
	name
	emai
	contact
	password
	address
	dob
	gender
	status = 0 and 1
Q13 Add data into tables using the INSERT query in MySQL ?
Ans. Insert single row syntax :
	INSERT INTO table_name
	(column1, column2, column3, ...)
	VALUES
	(value1, value2, value3, ....);
	
	Insert Multiple row syntax :
	INSERT INTO table_name
	(column1, column2, column3, ...)
	VALUES
	(value1, value2, value3, ....),
	(value1, value2, value3, ....),
	(value1, value2, value3, ....),
Q14. Select Query with where clause
Ans. Select query syntex
	a). select some column
		SELECT column1, column2, ...
		FROM table_name;
	b). select all columns
		SELECT *
		FROM table_name;
Q15. Use where clause
Ans. a). The WHERE Clause is use to filter records.
     b). It is use to extract only thoes records that fullfill a specified conddition.
     c). syntax:
		SELECT column1, column2, ...
		FROM table_name
		WHERE condition;
     d). Basic condition 
	=	==>	equal
	!=	==>	not equal
	>=	==>	greaterthan and equal
	<=	==>	lessthan and equal
	>	==>	greaterthan
	<	==>	lessthan
Q16. MySQL constraints
	NOT NULL
	UNIQUE
	DEFAULT
	CHECK
	FOREGIN KEY
	PRIMARY KEY
Q17. Commands: And, OR & NOT operator
Ans. AND Operator :- MySQL logical AND operator compare to expression and return true if both of the expression are true.
			Example ==> twinse condition true then true.
     OR Operator :- MySQL OR operator compare two expressions and returns true if either of the expression is true.
			Example ==> one condition true then true.   
     NOT Operator :- MySQL NOT operator reverse and negates the input.
			Example ==> true then false and false then true
     Syntax :- SEECT * FROM table_name
	       WHERE condition1 AND condition2;
				OR
				NOT
Q18. What is IN Operator ?
Ans. a). The IN OPERATOR allow you to specify multiple value in a WHERE clause.
     b). The IN OPERATOR is a Shortand for Multiple OR conditions.
     	Syntax :- SELECT * FROM table name
	          WHERE column_name IN
		  (value1, value2, ...);
Q19. What is LIKE Operator ?
Ans. The LIKE OPERATOR is used in a WHERE clouse to search for a specifies pattern in the column.
     WILD CARD
     a). The percent (%) sign is represents zero, one, or multiple characters.
     b). The underscore sign (_) is represents one single cheracters.
Q20. What is BETWEEN and NOT BETWEEN ?
Ans. check a range then use BETWEEN and NOT BETWEEN.
Q21. What is ORDER BY and DISTINCT
Ans. ORDER BY ==> Syntax :- SELECT * FROM table_name ORDER BY column_name ASC | DESC
     DISTINCT ==> Syntax :- SELECT DISTINCT column_name FROM table_name
Q22. What is IS NULL and IS NOT NULL ?
Ans. Syntax :- SEECT * FROM table_name WHERE column_name IS NULL | IS NOT NULL
Q23. What is LIMIT and OFFSET ?
Ans. LIMIT ==>  If want to LIMIT, the numbers of results that are returnd you can simply use LIMIT command with several rows to LIMIT by.
                Syntax :- SELECT * FROM table_name LIMIT 8;
     OFFSET ==> You can also specify an OFFSET from WHERE to start returning data.
                 Syntax :- SELECT * FROM table_name
			   LIMIT 6 OFFSET [Number of rows to skip];
Q24. Aggregate Funtion COUNT(), SUM(), AVG(), MIN(), MAX() ?
Q25. Update Quary Syntax ?
Ans. SELECT * FROM table_name SET value WHERE Clause {mandatory}
Q26. Delete Query Syntax ?
Ans. DELETE FROM table_name WHERE Clause {mandatory}
Q27. What is Commit and Rollback ?
Q28. What is Primary Key ?
Ans. a). Primary key always contains unique data
     b). Its cannot be null.
     c). There must be a single primary key.
     d). CREATE TABLE table_name(
					id INT NOT NULL AUTO_INCREMENT,
					name VARCHAR(50) NOT NULL,
					age INT NOT NULL,
					city VARCHAR(10) NOT NULL,
					PRIMARY KEY(id)
				);
Q29. What is Forign Key ?
Ans. a). The Foreign key is used to link two tables.
     b). A foreign key in one table (child table) is used to point PRIMARY key in another table (parent table).
     c). CREATE TABLE table_name(
					id INT NOT NULL AUTO_INCREMENT,
					name VARCHAR(50) NOT NULL,
					age INT NOT NULL,
					city INT NOT NULL,
					PRIMARY KEY(id)
					FOREIGN KEY(city) REFERENCES City (id) 
				);
Q30. What is MySQL INNER JOIN ?
Ans. a). The MySQL Inner Join is used to return only those result form the tables tha match the specified condition and hides other rows and columns.
     b). MySQL assumes it as a default Join, so it is optional to use the Inner Join keyword with the query.
Q31. What is MySQL LEFT JOIN ?
Ans. The MySQL LEFT JOIN keyword returns all record from the left table(table1), and the matched records from the right(table2).
Q32. What is MySQL RIGHT JOIN ?
Ans. The MySQL RIGHT JOIN keyword returns all record from the right table(table2), and the matched records from the Left(table1).
Q33. What is MySQL CROSS JOIN ?
Q34. What is Join Multiple Tables using MySQL Command ?
Q35. What are MySQL GROUP BY and HAVING ?
Q36. MySQL SubQuery with EXISTS and NOT EXIST ?
Q37. What is DROP ?