Tables
1. create a table
Create table command use to create new table in Database.
Ex :
CREATE TABLE employee_table(
id int NOT NULL AUTO_INCREMENT,
name varchar(45) NOT NULL,
age int NOT NULL,
);
2. Alter table
The ALTER statement is always used with "ADD", "DROP" and "MODIFY" commands according to the situation.
1. ADD :
- The ADD command is used to add the column definition of the table.
Ex :
ALTER TABLE employee_table(
ADD emp_Address varchar(255) NOT NULL;
);
2. MODIFY :
- The MODIFY command is used to change the column definition of the table.
Ex :
ALTER TABLE employee_table(
MODIFY emp_Address varchar(50) NOT NULL;
);
3. DROP column :
- use delete table from database.
Ex :
ALTER TABLE employee_table(
DROP emp_Address ;
);
Views
- A view is a database object that has no values.
- Its contents are based on the base table. It contains rows and columns similar to the real table.
- In MySQL, the View is a virtual table created by a query by joining one or more tables.
- It is operated similarly to the base table but does not contain any data of its own.