training Day1

                       Commands for MySQL

Mysql is basically a set of commands which help us to store some data in our database. 

Here are the commands for Mysql:

• create database database; - used to create database.
• show databases; - used to show all the databases present.
• use databasename; - used to currently use the database. After using this command only we can perform actions in it.
• create table tablename(column1 datatype1,column2 datatype2,........); - used to create table with its attributes.
• insert into tablename values(value1,value2,.....); - used to insert values in the table
• show tables; - used to check tables. It will work only after we use any database.
• drop database databasename; - used to delete / Remove database.
• desc tablename; - used to check table description.
• When we want to retrieve data from table we use : 

                                   Select 

                                   *      -  all columns

                                  from - table name

• When we want to retrieve specific data or column from the database we use : 

                                 Select

                                 from   - table name

                                 where - condition (eg : city = 'Ludhiana');

• Count command is used to tell the count of number of rows. We use command as :

                      Select count(columnname)as name from tablename;

• To add any column to existing table we use command :

                     alter table tablename add columnname datatype;

• To show data from particular range we use command :

                     Select * from tablename where condition >= and <=

  Example :  Select * from products where quantity >=2000 and <= 8000.

Note :- We can use OR also in similar way as we use AND.

• By default format of date in Mysql is YY-MM-DD.
• If we want something among range then we use command : 

                   Select * from tablename where condition between value1 AND value2;

 Example : Select * from products where quantity between 2000 AND 8000;

• To add entries in the new column or to update value in the existing column we use command :

                   Update tablename set columnname = value;

• If we want to add data or update any particular row we use command :

                   Update tablename set columnname = value where condition;

• Order by - It used to arrange in ascending/descending order. We use command as :

                    Select from tablename where orderby columnname;

Note :- By default the order is ascending order.

• Sum command :

                  Select Sum(column-name ) from tablename;

• Distinct :- It is used in select and is used to remove duplicate entries. We use command as:

                  Select distinct(column-name) from tablename;

• Group by :- Used to group two columns. We use command as :

                  Select from tablename group by columnname;