SQLTABLE Keyword
CREATE TABLE
TheCREATE TABLE command creates a new table in the database.
The following SQL creates a table called "Persons" that contains five columns: PersonID, LastName, FirstName, Address, and City:
Example
PersonID int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
);
CREATE TABLE Using Another Table
A copy of an existing table can also be created usingCREATE TABLE.
The following SQL creates a new table called "TestTables" (which is a copy of the "Customers" table):
Example
SELECT customername, contactname
FROM customers;
ALTER TABLE
TheALTER TABLE command adds, deletes, or modifies columns in a table.
TheALTER TABLE command also adds and deletes various constraints in a table.
The following SQL adds an "Email" column to the "Customers" table:
Example
ADD Email varchar(255);
The following SQL deletes the "Email" column from the "Customers" table:
Example
DROP COLUMN Email;
DROP TABLE
TheDROP TABLE command deletes a table in the database.
The following SQL deletes the table "Shippers":
Example
Note: Be careful before deleting a table. Deleting a table results in loss of all information stored in the table!
TRUNCATE TABLE
TheTRUNCATE TABLE command deletes the data inside a table, but not the table itself.
The following SQL truncates the table "Categories":
