SQL Tables Content

What is a Database Table?

  • Tables are the basic building blocks in any database.
  • They hold the rows and columns of your data.
  • You can create tables, change them, and remove them.
  • Normally, a user who creates a table is owner of the table and is responsible for granting permission to use it. That means how to give permission to use what and how.
  • When you create a table with SQL, you do at least the following:
    • Name of the table.
    • Name of the columns it contains.
    • Specify the data type of each column.
    • Specify the null status of each column - whether that column permits or forbids null values.
  • Almost all vendors have accepted additional possibilities for the CREATE TABLE statement which is supported in SQL-standard, including:
    • Defaults (values assumed when you don't explicitly enter anything, such as today's date, on a sales order).
    • Constraints that check (limit) the possible values you can enter for a column (for example, pub_ids can be 0736, 0877, or 1389 only).
    • Constraints that defines a column as primary key, unique, or both.
    • Constraints that defines index for columns to achieve fast search and data retrieval.
    • Constraints that can set up reference checks among primary and foreign keys.
© 2010 by Finnesand Data. All rights reserved.
This site aims to provide FREE programming training and technics.
Finnesand Data as site owner gives no warranty for the correctness in the pages or source codes.
The risk of using this web-site pages or any program codes from this website is entirely at the individual user.