SELECT is doubtlessly the most important command in SQL. A database is completely useless unless you can query the data it is holding. SELECT is how we query.
If you want to follow along:
You will need MS SQL Server installed. Here is a link to instructions: InstallSQL
Microsoft provides a great sample database known as Adventure Works. I am working with the 2012 release. You can download it here: AdventureWorksDownload
Once you have Adventureworks downloaded, you will need attach it to SQL Server.
Copy and paste the download file to somewhere you can find it. I recommend:
C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA
** the portion in red changes based on what version of SQL Server you downloaded.
Open SQL Server Management Studio. Windows Key + R – Type SSMS
Login to your server
Go to Object Explorer – Right Click Database > Attach…
Click Add…
Select Adventureworks2012_Data.mdf
In the bottom window, highlight the log file and click Remove. Then Click Okay
Go back to Object Explorer. Expand Databases > AdventureWorks2012 > Tables
Just picking a table at random, I selected HumanResources.Employee. Let us see what is in the table. Click the New Query button up top, and a new query window will open.
Make sure you are working with the right database. Select AdventureWorks2012 from the drop down:
Cut and Paste the following into the new query window.
select *
from HumanResources.Employee
go
select JobTitle, BirthDate, Gender, HireDate
from HumanResources.Employee
go
select JobTitle as Job, BirthDate as DOB, Gender, HireDate as [Start Date]
from HumanResources.Employee
go
select HireDate as [Start Date], JobTitle as Job, BirthDate as DOB, Gender
from HumanResources.Employee
order by HireDate
go
select HireDate as [Start Date], JobTitle as Job, BirthDate as DOB, Gender
from HumanResources.Employee
where gender like ‘F’
order by HireDate
go
One cool thing about SQL code is that you can select only the code you want to execute
Highlight the first group of code and click the ! Execute button
Syntax
- Select * – Select all fields in the table. “*” is a wildcard in SQL
- from HumanResources.Employee – this is the table we want to work with
- go – this indicates and end to the code block. It is not needed when executing code block by block (like we are doing here), but it is a good practice to get in the habit of adding it
Notice the results show every field in the table. It displays in a spreadsheet like table
Now Select the next code group and click ! Execute
Syntax
- select JobTitle, BirthDate, Gender, HireDate – Here we are selecting four specific columns from the table
- The rest is same as above
Results show the 4 columns selected above
Next block of code – click ! Execute
- select JobTitle as Job, BirthDate as DOB, Gender, HireDate as [Start Date] – In this case, we use the “as” command to give the field names more User friendly names
Note the column names have changed
Next block of code – click ! Execute
syntax
- select HireDate as [Start Date], JobTitle as Job, BirthDate as DOB, Gender – here we reordered the fields so that HireDate appears first
- order by HireDate – this SQL for Sort by. The results will now be ordered by HireDate
Notice Start Date(HireDate) is now the first column and the records (rows) are sorted in order from oldest Start Date to newest
FInal block of code – click ! Execute
Syntax
- where gender like ‘F’ – here we are filtering the results to only ones were Gender is F.
Note now only Female employees are in the results
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