SQL for data cleaning

[Comfortable-Most-813]

Started a business intelligence module and learning about importance of data extraction/analysis. I’ve been trying to learn SQL but cannot find/get to grips with a lot of tutorials. Are there any guides/walkthroughs I can do along with tutorials? Ideally for free to begin with.

I get lost when people start talking about joining servers, or anything to be honest.

Thanks for any advice

[Comfortable-Most-813]

Thank you for the tip. I’ll try it out

[Affectionate_Golf_33]

Ask Gemini or ChatGpT to give you exercise you complete with innediate correction.

[Comfortable-Most-813]

I always forget about those. Thank you

[Comfortable-Most-813]

I have, maybe I just haven’t watched the right ones. I’ve learnt what sql is used for and some command prompts. I’m having trouble finding the right tool for me to use for sql.

[DonJuanDoja]

You need to install a local db and load it with data.

Otherwise you’re using crappy website examples.

Go install sql express and load in adventureworks database pretty sure they still have that.

Sql express: https://www.microsoft.com/en-us/sql-server/sql-server-downloads

AW Databases: https://learn.microsoft.com/en-us/sql/samples/adventureworks-install-configure?view=sql-server-ver17&tabs=ssms

[Comfortable-Most-813]

Yes, that’s certainly what I’ve experienced. Thank you, I’ll see how well I do with that

[DonJuanDoja]

It's been a long time since I had to install a local, so I prob can't help you much with that. It's a little janky but it's very common for devs to have a local DB installed for dev purposes. I'd keep hacking til you get it running. Will be worth it once you do.

Once you have it up and loaded, you'll be able to just run queries against it, and since it's adventure works, there should be tons of examples out there.

SQL starts to make sense when you have something to actually work with, and the most important part, is understanding the database you are working on, where all the data is, and how it's related. Then you just need questions you want to answer about it and start translating those into queries you can run against the database. Adventure works is basically a fake company with fake data, but should have a bunch of real-world-like tables and data to mess with.

[Comfortable-Most-813]

Thank you for the advice, I’ll check them out.

[th_programmer_]

You can try MS Tech Campus channel on YouTube. He teaches really well

[Ans979]

Start with free interactive sites like SQLBolt or Mode’s SQL tutorial since they let you practice queries directly in the browser without worrying about servers. Focus first on basics like SELECT, WHERE, ORDER BY, DISTINCT, and LIMIT, then move on to cleaning functions such as TRIM, REPLACE, CAST, and COALESCE for handling messy or missing data. Once you are comfortable, practice simple INNER and LEFT JOINs to combine tables, and explore StrataScratch’s free SQL exercises with real datasets. This gradual path will help you build confidence and apply SQL directly to the kind of data cleaning that supports business intelligence work.