CREATE TABLE Statement

SQL: CREATE TABLE Statement


The CREATE TABLE statement allows you to create and define a table.
The basic syntax for a CREATE TABLE statement is:
CREATE TABLE table_name
( column1 datatype null/not null,
  column2 datatype null/not null,
  ...
);

Each column must have a datatype. The column should either be defined as "null" or "not null" and if this value is left blank, the database assumes "null" as the default.

For example:
CREATE TABLE suppliers
( supplier_id number(10) not null,
  supplier_name varchar2(50) not null,
  contact_name varchar2(50)
);



Practice Exercise #1:
Create a customers table that stores customer ID, name, and address information. The customer ID should be the primary key for the table.
Solution:
The CREATE TABLE statement for the customers table is:
CREATE TABLE customers
( customer_id number(10) not null,
  customer_name varchar2(50) not null,
  address varchar2(50),
  city varchar2(50),
  state varchar2(25),
  zip_code varchar2(10),
  CONSTRAINT customers_pk PRIMARY KEY (customer_id)
);



Practice Exercise #2:
Based on the departments table below, create an employees table that stores employee number, employee name, department, and salary information. The primary key for the employees table should be the employee number. Create a foreign key on the employees table that references the departments table based on the department_id field.
CREATE TABLE departments
( department_id number(10) not null,
  department_name varchar2(50) not null,
  CONSTRAINT departments_pk PRIMARY KEY (department_id)
);


Solution:
The CREATE TABLE statement for the employees table is:
CREATE TABLE employees
( employee_number number(10) not null,
  employee_name varchar2(50) not null,
  department_id number(10),
  salary number(6),
  CONSTRAINT employees_pk PRIMARY KEY (employee_number),
  CONSTRAINT fk_departments
    FOREIGN KEY (department_id)
    REFERENCES departments(department_id)
);

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