<

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x

SQL 101 - SELECT

Published on
8,632 Points
2,532 Views
1 Endorsement
Last Modified:
Approved
The first thing you need to know when learning SQL is how to get data out of a database.  This means learning the SELECT command.  Using this command will get the SQL server to return data to you. You can use this command to do some simple math, or to do the common "Hello World!" application you all learn the first day of a programming course.
SELECT 1 + 1

Open in new window

output
 2

Open in new window


SELECT 'Hello World'

Open in new window

output
Hello World

Open in new window


Keeping this in mind can become useful later, when you need to have the server return debugging statements to you during particularly long code writing sessions.  But usually you'll need the SELECT command to lookup a certain piece of data from a table.  Let's assume you have a table of products.  In this table there are several columns, one of which is productName.  If you wanted to get a list of every product in your table, you can write the following command:
SELECT
   productName
FROM products

Open in new window

output

  productName
  -----------
  pencil
  pen
  paper
  Mountain Dew

Open in new window

I'd like to point out the data returned is not ordered.  In later articles I'll show you how to put the results into any order you may find useful.  But for now, let's stick to learning about the SELECT statement.

What if you wanted to know the name and the price?  In SQL you can list as many columns as you like, in a comma separated list.
SELECT
   productName, price
FROM products

Open in new window

output

  productName     price
  -----------     -----
  pencil          .25
  pen             .99
  paper          1.00
  Mountain Dew   1.25

Open in new window


Finally, if you want to return all the data of the table, you can do that too.  But I would like to point out using the following command on a table a lot of rows (thousands, or millions) could be very time and processor consuming.  Use this only if you know the number of records and columns will be small enough your server and connection can handle.  There are also many reasons NOT to use this, but I'll show you how to do it anyway.
SELECT  *
FROM products

Open in new window

output

  productName     price   quantity   color
  -----------     -----   --------   -----
  pencil          .25      100        yellow
  pen             .99       73        blue
  paper          1.00      500        white
  Mountain Dew   1.25        8        green

Open in new window


As always, if you have any questions, please let me know!  I'm here to help you understand SQL Server better.  Let me know how I can do that.

1
Comment
0 Comments

Featured Post

Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

Join & Write a Comment

Using examples as well as descriptions, and references to Books Online, show the documentation available for date manipulation functions and by using a select few of these functions, show how date based data can be manipulated with these functions.
Stellar Phoenix SQL Database Repair software easily fixes the suspect mode issue of SQL Server database. It is a simple process to bring the database from suspect mode to normal mode. Check out the video and fix the SQL database suspect mode problem.

Keep in touch with Experts Exchange

Tech news and trends delivered to your inbox every month