CREATE TABLE Statement is used to create a New Table (Relation) in database. Table is used to store information in the database.
Syntax: Create Table command has the following form.
For each column, a name and a data type must be specified and the column name must be unique within table definition. Columns are separated by colons.
- Not Null clause indicates that column can’t be empty.
- Unique clause indicates that only distinct value is allowed in the column.
- Column constraint and Table constraint specify the different constraint applied in the table.
1. Create Salesman Table
In this example, we have created SALESMAN table with SNUM as a Primary key (means you can’t insert duplicate values as well as SNUM is mandatory field) and SNAME as a mandatory field.
2. Create Customer Table
In this example, we have created CUSTOMER table with CNUM as a Primary key, CNAME as a mandatory field and SNUM is the reference of SALESMAN table.
3. Create Orders Table
In this example, we have created ORDERS table with ONUM as a Unique and mandatory field, SNUM is the reference of SALESMAN and CNUM is the reference of CUSTOMER.