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In this video, you're going to learn the basics of SQL querying in just 15 minutes.
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And by the time we're finished, you'll be wondering what all the fuss was about.
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Are you ready?
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Then let's get started.
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Hello and welcome to Vitamin BI, bringing you business intelligence for beginners and beyond.
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On this channel I help you do more with data, so if you're new here consider subscribing.
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Right, so as I said in my intro I'm going to teach you the basics of SQL querying,
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the essentials that you'll need to know if you're considering becoming a business intelligence analyst.
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Obviously we can only go so far in 15 minutes, but I promise you
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that by the time we're finished
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you'll be able to understand quite a lot of what you might be called upon to do.
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We'll be focusing specifically on querying data, not creating or deleting databases,
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tables or data, just selecting data from tables that we want to return for our specific needs.
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Before we get started, let me give you a little context.
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You might be wondering why you need to learn SQL with BI tools becoming more and more sophisticated.
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Can't they write the SQL queries for me the answer to
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that is yes and no yes
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when it comes to requesting data for different charts graphs and tables
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that you might want to present in dashboards in these cases
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the bi tool will have some kind of graphical interface to be able to drag
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and drop fields to return data but no in
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that in a lot of cases you'll need to write sql queries to pre -aggregate filter
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and select only the data necessary for the project that you're working on.
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These are often called views and you create views mainly
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because it's more efficient than connecting to all data when you only need some of it.
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So you could have a table that contains millions of rows of data
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but by creating a view of it your BI tool will
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only need to work with a few thousand making analysis and presenting results much faster.
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So you see, knowing how to query with SQL is a useful skill to have.
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Let's jump onto my computer and get started.
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So today we're working with a SQLite database that I found online, containing data compiled from the FIFA video game by EA Sports.
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So soccer stats.
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I'll leave a link to the database in the description if you want to play around with it too.
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In terms of the tool I'm using to query the database?
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It's called NaviCat.
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It's the premium version that allows you to connect to and query pretty much any relational database.
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But they also have a version for specific RDBMS like MySQL, SQL Server, etc. Link also in the description.
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Here we're in the NaviCat interface.
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On the left we can see that I'm connected to the SoccerDB connection
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that I've created and in that connection is a database called main and in that database we have various tables country,
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league, match, player etc. We're going to be working mainly with the player table.
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If I double click it we'll see the data contained within that table.
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We've got three different IDs, player name, birthday, height and weight.
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What I want to do is write SQL queries
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and ask the database to return specific data from this table so I'll open a new query window.
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Now when we're asking for data we're using what's called a select statement
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so that's what we need to write first and
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if we want to return the whole table in the result we do so with a star.
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Then we specify the table that we want to select everything from.
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In this case the table called player select star from player then we run the query
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and the database returns all data from that table you may notice
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that i've written everything in lowercase
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because the sequel isn't case sensitive however i have the option to what's called beautify the sequel
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and when i do you'll notice that select
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and from have been capitalized although it's not obligatory this does actually make your queries easier to read.
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It's not so important with such a small query like this one
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but when you've got one with tens if not hundreds of lines of code it really does make life easier.
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So we've selected all fields or columns and all rows from the table
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but what if we only want to select specific fields?
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Simple.
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Instead of the star we just write out the field names
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we want separated by commas like this player underscore name comma birthday I run this,
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and those are the fields returned.
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When we select specific fields, we can also rename them by creating aliases.
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To do this, we use the as function.
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So player name as name.
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And we can see that update.
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We could specify an alias containing a space, but to do this, we would need to put the name in quotes like this.
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Full name.
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Let's go back to all data
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and look now at how we can ask the database to only return specific rows in the result.
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To do this we use a WHERE clause with different operators.
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For example, we could select only players with a weight of 190 pounds.
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So we use the equals operator.
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We could also select any player with a weight greater than 190 pounds or greater than or equal to 190.
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You see, it's not that complicated.
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And we've gone from over 11 ,000 records to just under 1 ,000 being returned.
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We can also specify more than one condition by using either
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and or or so weight greater than 190 and height greater than 190
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so both conditions must be met if I change it to
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or it means that either condition must be met in order for the row to be returned
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so that's selecting rows based on the value in integer fields what about when it comes to text values?
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Well, we can also use the equals operator to find any row where the text matches exactly with what we specify.
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PlayerName equals Aaron Galindo.
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But we could also use the like operator which achieves the same goal.
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But what if we want to select just rows from all players called Aaron?
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So basically the player name field starts with Aaron.
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Here we can use a percent character after the text to look for, like so.
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And we get all Arons returned.
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If we wanted to find any player name that ends with Aaron, we put the percent character before.
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Nothing that ends with Aaron.
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We could put a percent before and after, which would basically mean any player name that contains Aaron.
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And we've got Rolando Arons.
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Finally, here's an example which puts the percent in the middle of text.
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So here we'll return all rows where the player name starts with a and ends with n.
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you can go even further with the like operator by using
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underscore to represent single characters an example would be like t underscore m percent
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so the underscore is asking for any rows where the player name starts with t
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then any character between the t and the m followed by anything and run.
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We've got Tamas, Tamir, Tim, Timmy, etc.
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There are also things called wildcards that allow you to go even further
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when specifying the rows you want to return but we won't go into those for this video.
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We will however finish looking at the where clause by talking about a couple more operators that you can use.
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For text fields we have in which allows us to specify multiple or statements, more simply.
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However, it can only be used for exact matches, so we can't use percents or underscores with it.
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So let's look for Ronaldo and Messi.
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Open brackets Cristiano Ronaldo, Lionel Messi.
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For integers, we can use the between operator.
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So I could say wear weight between 180 and 190.
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Finally we have the isNull and isNotNull.
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Null being empty.
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In this table we don't have any null values.
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But if I open up the match table we can see that there are lots in there.
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So select star from match where home player 1 is null. or is not null.
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There we go.
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Let's go back to our player table and see how we can sort results.
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We can do this using the ORDER BY clause.
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The rows are currently sorted by the ID field in ascending order.
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But if we wanted to sort by weight, we can say ORDER BY WAIT.
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This sorts by weight in ascending order, because that's the default sorting method when not explicitly specified.
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But we can change this to descending order by adding DESC now we can see who the heaviest player is
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when it comes to sorting data using order by this isn't something that's overly important for our use case
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because when we're selecting data to create views we're usually then going to connect
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that view to a bi tool and use
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that for building individual chart queries
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and these tools will let you apply sorts to the data
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now we're going to look at how to join data from different tables.
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To demonstrate this I'm going to use the player attributes table.
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We can see that in this table we have the player ID but not the player name.
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To be able to create a view containing the player name plus the overall rating
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we would need to join the data from the player attributes and player tables.
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I'm going to start by specifying player API ID comma date comma overall rating.
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Now I want to get the player name from the player table.
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How do I do that?
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Well because we're going to need fields from two different tables we need to specify which field comes from which table.
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We do this by writing the table name dot field name.
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So player attributes dot player API ID.
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Same for date and overall rating.
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Now we can specify, perhaps after the player ID, player dot player name.
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If I run this I'll get an error saying
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that there's no such column as player .playerName because we're saying that we're looking for it in the player attributes table.
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This is when we need to specify the joining of the tables using one of the four join types.
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I'm not going to go into them in this video
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but I'll probably do a separate video that explains them in more detail so don't forget to subscribe.
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So in this case we'll use an inner join
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and we'll say inner join player the player table on
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and now we specify what fields
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we want to use to create the join in this case we're going to use the player api id field
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which is contained in both tables
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and again we have to add the table name first dot field name equals player dot player API ID and run.
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Now we have the player name appended to the player attributes table data.
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Pretty clever right?
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But let me show you something even more clever.
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I showed you earlier how to use the as function to create aliases for fields.
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Well we can actually do this for tables as well which makes the query much cleaner.
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First I'm going to give the player attributes table an alias of a and the player table an alias of b.
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I just need to write these two letters after where I've specified each table.
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So a after player attributes here and b after player here.
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Once I do this I can now replace the table name for each field like this.
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You see, much cleaner.
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So, you may notice that there are multiple rows for each player on different dates.
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So how would we add up all of these different values for each player?
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Well, to do this, we're going to want to aggregate the data using the SUM aggregator.
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I'll add this to the overall rating field and run the query.
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Ah, that's not what we were expecting.
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But that's because we haven't specified in the query how we want to group the data together.
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This is when we need to use the GROUP BY clause.
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When we use the GROUP BY clause we need to add into it all of the fields that we need to group.
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So in this case essentially all fields apart from the overall rating.
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A .PlayerApiId, B .Playername, A .Date And run
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This is correct, but not exactly what we want.
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We want to combine all of the ratings for the different dates,
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so we actually want to remove the date field from the specified fields as well as the group by. and run.
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That's better.
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But let's clean it up by aliasing the sum overall rating as rating.
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Let's sort this descending.
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Order by rating descending.
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Strange that Ronaldo and Messi aren't in there at the top.
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Let's try and see why this is.
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Perhaps there are just more entries for some players when we sum them up.
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To find this out, we could add a count of b .playerName.
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And yes, in this case how about using an average?
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I'll replace sum with average, avg, and run.
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And there we go, that makes more sense.
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We're going to go one step further and filter this result.
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To do that we can use the HAVING clause.
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The HAVING clause is only applied to the result of the GROUP BY function, so isn't the same as the WHERE keyword that's applied before.
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And it's only applied to numeric values, so in this case I'm going to ask for only ratings above 85.
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I need to write it directly after the group by and before the order by.
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So having rating greater than 85 and run.
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Only 26 records.
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And there we have our final query.
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I'll beautify it and this is what it should look like.
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You can see that all of the SQL keywords are capitalised.
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And you can see that we've come a fairly long way in a very short space of time.
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We've only covered a very small part of SQL as a whole, so there's masses more to learn.
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But what I've shown you today is a really good foundation for giving you the confidence to dive deeper.
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Did I not say that once we'd finished, you'd wonder what all the fuss was about?
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If you got value out of this video, please do like, share
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and subscribe for more videos like this one why not start with this playlist here as always thanks for watching
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I've been Adam Feiner and until the next time stay BI curious

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Лексика и советы по произношению к этому уроку

Этот урок разговорной практики построен на видео «Learn Basic SQL in 15 Minutes». Чаще всего повторяются слова: player, table, field, row, select. В этом видео 201 предложений и 2466 слов для шедоуинга. Речь длится 17:28. Говорящий держит ровный темп — около 141 слов в минуту, удобный для шедоуинга. 84% слов входят в 3000 самых частых слов английского языка; остальные стоит разобрать перед занятием.

Ключевая лексика этого видео

15 слов из видео, которые стоит выучить, с произношением и значением:

СловоПроизношениеЗначение
query существительное/ˈkwɪɹ.i/запро́с, вопро́с
select глагол/sɪˈlɛkt/отбира́ть
database существительное/ˈdeɪtəˌbeɪs/ба́за да́нных
rat существительное/ɹæt/кры́са, пасю́к
operator существительное/ˈɑpəˌɹeɪtɚ/телефони́ст, телефони́стка
clause существительное/klɔːz/предложе́ние
attribute существительное/ˈæt.ɹɪˌbjut/сво́йство, характе́рная черта́
connect глагол/kəˈnɛkt/свя́зывать, связа́ть
null существительное/nʌl/нуль, пусто́е по́ле
subscribe глагол/səbˈskɹaɪb/подпи́сывать, подписа́ть
chart существительное/t͡ʃɑɹt/морска́я ка́рта
rating существительное/ˈɹeɪtɪŋ/ре́йтинг
filter существительное/ˈfɪltɚ/фильтр
clever прилагательное/ˈklɛv.ɚ/иску́сный, ло́вкий
interface существительное/ˈɪn(t)ɚˌfeɪs/интерфе́йс

Фразовые глаголы, которые вы услышите

СловоЗначение
write out глаголписа́ть по́лностью

Фразы, которые стоит повторять

Короткие законченные фразы из видео, которые пригодятся в повседневном разговоре:

  • Let's jump onto my computer and get started.
  • In terms of the tool I'm using to query the database?
  • You see, it's not that complicated.
  • In this table we don't have any null values.
  • How do I do that?

Грамматика в этом видео

Конструкции, которые говорящий использует чаще всего, с точными словами из видео:

КонструкцияВ видео
Условные предложения if + предложение, will/would + глагол — условие и его результатIf I double click it we'll see · If I run this I'll get
Present Perfect have/has + причастие прошедшего времени — прошлое действие, важное сейчасI've created · i've written · have been capitalized
Пассивный залог be + причастие прошедшего времени — важно, что происходит, а не кто это делаетmight be called · are often called · have been capitalized
Вероятность с «might / may» might/may + глагол — возможно, но не точноmight be · might want · may notice

Произношение, на которое стоит обратить внимание

Говорящий использует 70 сокращённых и редуцированных форм, например we're, I'm, I'll. Произносите их коротко, так, как слышите.

  • Звуки «sh» и «zh»: efficient /ɪˈfɪʃənt/, essentially /ɪˈsɛnʃəli/, dashboard /ˈdæʃˌboɹd/
  • Длинные слова — следите за ударением: operator /ˈɑpəˌɹeɪtɚ/, complicated /ˈkɑm.plɪˌkeɪ.tɪd/, essentially /ɪˈsɛnʃəli/, aggregator /ˈæɡɹɪˌɡeɪtɚ/, capitalize /ˈkæpətəˌlaɪz/

Звуки, трудные для русскоязычных:

  • /w/ — губы округлены, это не /v/: query /ˈkwɪɹ.i/, sequel /ˈsiːkwəl/, keyword /ˈkiː.wɜːd/
  • Звонкие согласные в конце слова — не оглушайте их: clause /klɔːz/, subscribe /səbˈskɹaɪb/, descend /dəˈsɛnd/, pound /ˈpaʊ̯nd/, complicated /ˈkɑm.plɪˌkeɪ.tɪd/

Как заниматься с этим видео

  1. Прослушайте всё видео один раз молча и выпишите незнакомые слова.
  2. Повторяйте предложение за предложением на обычной скорости, пока ваш ритм не совпадёт с ритмом говорящего.
  3. Запишите себя и сравните с оригиналом, обращая внимание на такие слова, как query, select, database.

Что такое техника Shadowing?

Shadowing — это научно обоснованная техника изучения языка, изначально разработанная для подготовки профессиональных переводчиков и популяризированная полиглотом доктором Александром Аргуэльесом. Метод прост, но эффективен: вы слушаете аудио на английском от носителей языка и немедленно повторяете вслух — как тень, следующая за говорящим с задержкой в 1–2 секунды. В отличие от пассивного прослушивания или грамматических упражнений, Shadowing заставляет мозг и мышцы рта одновременно обрабатывать и воспроизводить реальные речевые паттерны. Исследования показывают, что это значительно улучшает точность произношения, интонацию, ритм, связную речь, понимание на слух и беглость речи — что делает его одним из самых эффективных методов для подготовки к IELTS Speaking и реального общения на английском.

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