Join Bill Weinman for an in-depth discussion in this video Formatting SQL, part of SQL Essential Training (2014).
While the basic syntax for SQL is very simple. It is possible and common, to create some very complex SQL statements. For example, this statement. Which is not very complex by SQL standards. Selects names and populations for countries whose population is over one million. Because white space is ignored in SQL, except to separate tokens, these two statements are exactly the same. One is clearly more readable than the other, but they will both work the same.
How you format your SQL is entirely up to you. It's a matter of style, not substance, but it is important I'm not going to give you a lot of rules about it. And over the body of this course, you'll see how I do it. But I will tell you that it's important that you find your style and stick with it consistently. As your SQL gets more complex, it becomes more important that it is readable, and indentation and formatting become much more important. For example, this more complex query. Returns the capital cities of countries with more than a million population in order of continent and population.
For my part, I tend to indent SQL with two spaces, and I indent things under what they are related to. I also tend to begin my indentations with key words, and leave expressions hanging wherever possible. This is the style that works for me. Feel free to use it, but also feel free to develop the style that works for you. However you choose to format your SQL, it's important that you find it readable, and that you apply your rules consistently.
- Understanding SQL terminology and syntax
- Creating new tables and records
- Inserting and updating data
- Writing basic SQL queries
- Sorting and filtering
- Accessing related tables with JOIN
- Working with strings
- Finding the numeric type of a value
- Using aggregate functions and transactions
- Updating a table with triggers
- Creating views
Skill Level Beginner
Q: For Mac OS X: When I try to start the Apache Web Server from the XAMPP control panel, it doesn't start, and when I open "localhost" in my web browser, I see a white screen that says "It Works!" instead of the XAMPP page.
sudo apachectl stop
Q: I'm on a Mac, and I get an error in SID that says "attempt to write a read only database." How can I fix this?
A: This usually means that the database folder does not have sufficient permissions for writing by the web user. This can happen if you create the SQL folder new, rather than copying it from the Exercise Files. Here's how to fix this:
- Open a Finder window and Navigate to /Applications/XAMPP/htdocs/SQL
- Control-click on the SQL folder and select "Get Info" from the context menu.
- Under "Sharing and Permissions" (you may need to open the disclosure triangle), in the "everyone" row, select "Read & Write."Then you can close the Info window.
- Now repeat the process for the three *.db files inside the folder.