MySQL is the most popular Open Source Relational SQL database management system. MySQL is one of the best RDBMS being used for developing web-based software applications.

RDBMS Terminology:

Before we proceed to explain MySQL database system, let’s revise few definitions related to database.

Database: A database is a collection of tables, with related data.
Table: A table is a matrix with data. A table in a database looks like a simple spreadsheet.
Column: One column contains data of one and the same kind, for example the column postcode.
Row: A row is a group of related data, for example the data of one subscription.
Primary Key: A primary key is unique. A key value can not occur twice in one table. With a key, you can find at most one row.
Foreign Key: A foreign key is the linking pin between two tables.

Installing Process

[root@host]# rpm -i MySQL-client-5.0.9-0.i386.rpm
          [root@host]# rpm -i MySQL-level-5.0.9-0.i386.rpm
          [root@host]# rpm -i MySQL-shared-5.0.9-0.i386.rpm 
          [root@host]# rpm -i MySQL-bench-5.0.9-0.i386.rpm

Query in MySQL:

Basic Queries are

Create database

Creating separate space in MySQL.

Syntax:

create database <DB_Name>;

To use the created Database

Syntax:

use <DB_Name>;

Create table

Creating table in Database

Syntax:

create table <TableName>(Column1 Datatype,Column2 Datatype,...);

Insert table

Insert data in created table

Syntax:

insert into <TableName> 
          values('string_data',integer_data,....);

Select table

To retrieve data from table.

Syntax for access all Rows:

select * from <TableName>; (or) select 
          <column_name> from <TableName>;

Syntax for access particular Rows:

select * from <TableName> where 
          <column_name>='<user_data'>;

View table

Create view table form existing table.

Syntax:

create view <ViewTableName> as 
          select <Column1>, <Column1> from <OldTableName>;

Delete table

To delete data or table

Syntax for delete all data:

 delete table <TableName>;

Syntax for delete particular data:

delete table <TableName> where <ColumnName>="
          <userdata>"

MySQL aggregate functions:

Avg

The AVG function calculates the average value of a set of values. It ignores NULL values in the calculation.

Syntax:

select AVG(<ColumnName) from <TableName>;

Count

The COUNT function returns the number of the rows in a table.

Syntax:

select COUNT(*) from <TableName> (or) select 
          COUNT(<columnName>) from <TableName>;

Sum

The SUM function returns the sum of a set of values.

Syntax:

 select SUM(<ColumnName>) from <TableName>;

Min

The MIN function returns the minimum value in a set of values.

Syntax:

 select MIN(<ColumnName>) from <TableName>;

Max

The MAX function returns the maximum value in a set of values.

Syntax:

   select MAX(<ColumnName>) from <TableName>;

MySQL with node.js

Example:
                nodejs with MySQL
                var express    = require("express");   
                var mysql  = require('mysql');  
                var connection = mysql.createConnection({   
                host     : 'localhost',       
                user     : 'root',                
                password : '',                
                database : 'address_book'         
                }); 
                  var app = express();
                  connection.connect(function(err){   
                  if(!err) {
              console.log("Database is connected ... nn");
              } else {
              console.log("Error connecting database ... nn");   
          }
          });

                app.get("/",function(req,res){
              var query="select * from register where 
                urname='"+req.body.urname+"' and 
              pw='"+req.body.pw+"'";
                connection.query(query, function(err, 
            rows, fields) {    
          connection.end();
            if (!err)
          console.log('The solution is: ', rows);
          else
          console.log('Error while performing Query.');
            });
          });
            app.get("/",function(req,res){
            connection.query('insert into user values('+1+','+sathiya+','+sathiya@gmail.com+','+sathiya2901+')', function(err, rows, fields) { 
          connection.end();
          if (!err)
          console.log('The solution is: ', rows);
          else
          console.log('Error while performing Query.');
          });
          });
          app.listen(3000);