How to Alias a Table in SQL! Understand Table Addressing

hello welcome back to the channel uh today's video will be the next step in our introduction to SQL tutorial and today specifically we'll be looking at uh using aliases in SQL so previously we've uh already covered using select from where order by um and the top functionality in SQL and this will kind of be the next step in the process and uh what I have up here is kind of a query that I start most of the videos from I select all the data from this initial employee table that I created um and for this video to show why aliases are so important I created a second table that I call the sales table and what I've done is just made this table where I just make employee name and then their total sales for the year that's it that's all that's in the table right here um but uh the reason I wanted to have two tables for this one is because using aliases is a really useful shortcut when you start having to type in um your table name over and over again so what I mean by an alias is you're going to take something like a table name or you could do it for a column name as well and you can redefine it and say select employee table as and let's say instead of typing employee table every time we want to say ET and then we'll also say we want the sales table and we're going to um say that's going to be as uh we'll just call that one St okay so um this is probably just because I haven't refreshed everything yeah that's fine um but then so now what we've done is when we want to uh say what we specifically want so all I want to get from here is um is just the employee name so I'm going to say e right from the employee table and we'll grab the employee name and then let's grab from the sales table St uh what their actual sales for the year have been and then let's say we want to compare all of that to what we're paying them so we grab from the uh employee table we grab their salary as well so rather than have to type in employee table sales table employee table I've just been able to say ET St um and then what will that is a filter condition um and we'll say where the ET um. employee is equal to the St Dot and we called it employee name over there so what we're saying is inside the sales table uh grab the um any row that has the same employee table name so uh something we'll cover in a later video called an inner join can create one master table based on um two separate tables and this is kind of a simpler way of doing the same type of thing where we're saying when the employee uh name is equal to the employee in the employee table then pull in the employee name the sales data and the salary so if we go ahead and run this I know I got the red squiggly lines but that's just cuz the thing hasn't refreshed yet um but you can see we get only the two salespeople what their sales for the year were and what their salary is um which is pretty cool but uh just to show why we need this if if we just didn't have a wear condition in this query and we tried to grab all this you get all of the data but the sales is the S the sales is meaningless I mean there's it doesn't know anything to correlate it with so it takes every entry that it has for sales which fortunately is just two it has 20,000 and 30,000 and if if you don't tell it how to correlate one piece of data to the other it takes every col every row of sales data and applies it to every entry in the employee table so obviously uh telling it how this data is related is very important um and then uh the other thing you could do is in in right instead of this being the employee from the employee table you could say St and then call it the employee name and uh that's going to give you exactly the same thing as when we called it employee because um right that's what we're combining them on so that it should make sense that those two things are the same and if I were to put the et. employee in here with the other guys as well you're just going to get the exact same column twice right so this is obviously whatever your common piece between the two tables is that's what you want to join them on when you use your wear statement comparing them uh you can also one thing worth mentioning you can also Alias actual column names so if you want to Alias uh employee name as en um you could do that and then you could come down here and say st. instead but most of the time you're not going to want to Alias uh columns at least I don't um it's super useful for aliasing tables where you pull a lot of data in um but that's kind of a quick introduction to aliasing that's a pretty important pretty easy sequel concept hopefully you found that useful and uh if you have any questions or you know why uh when I aliased that column name it goofed up just let me know about in the comments below and I'll try to respond as quickly as possible if you found this or anything else on the channel useful I really appreciate a like and a subscribe it helps Channel out a ton and as always good luck with your projects and thanks for watching thanks bye bye