saving work on SQL interlude problems, problem 16 complete so far

invoice_37_line_item_count.sql

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+SELECT COUNT(InvoiceLineId)
+FROM InvoiceLine
+WHERE InvoiceId = 37;
+

line_item_track.sql

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+SELECT InvoiceLine.*, Track.Name FROM InvoiceLine AS Track_Name
+INNER JOIN Invoice
+ON Invoice.InvoiceId = InvoiceLine.InvoiceId
+INNER JOIN Track
+ON InvoiceLine.TrackId = Track.TrackId
+GROUP BY Invoice.InvoiceId;
+
+SELECT InvoiceLine.*, t.Name
+FROM InvoiceLine
+JOIN Track t on InvoiceLine.TrackId = t.TrackId;

line_item_track_artist.sql

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+SELECT InvoiceLine.*, t.Name, t.Composer
+FROM InvoiceLine
+JOIN Track t on InvoiceLine.TrackId = t.TrackId;

line_items_per_invoice.sql

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+/* My theory */
+SELECT COUNT(InvoiceLineId)
+FROM InvoiceLine
+GROUP BY InvoiceLine.InvoiceId;
+
+/* Correct Answer */
+select i.InvoiceId, count(il.invoiceId) line_item_count
+from Invoice i
+join InvoiceLine il on i.InvoiceId = il.InvoiceId
+group by il.InvoiceId;

playlists_track_count.sql

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+SELECT Playlist.Name, COUNT(PlaylistTrack.TrackId) AS Playlist_Track_Count FROM Playlist
+INNER JOIN PlaylistTrack
+ON Playlist.PlaylistId = PlaylistTrack.PlaylistId
+GROUP BY PlaylistTrack.PlaylistId;
+
+-- WHERE was messing up the results, GROUP BY was the appropriate syntax.

project_notes.md

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+# Project Notes - SQL Interlude - Chinook
+
+## Questions
+### How to use NOT in queries
+Why does
+
+```
+SELECT * FROM CUSTOMER
+WHERE COUNTRY NOT LIKE 'USA';
+```
+
+work and
+
+```
+SELECT * FROM CUSTOMER
+WHERE COUNTRY NOT 'USA';
+```
+does not work?
+
+### Answer
+To avoid using `LIKE` <br/>
+
+`WHERE NOT customer.country = "USA";` <br/>
+or <br/>
+`WHERE NOT != "USA";` <br/>
+
+are valid ways of forming the query.
+
+## Resources
+[How to concatenate columns in SQL - CONCAT_WS()](https://www.w3schools.com/sql/func_mysql_concat_ws.asp)
+
+## New Concepts/Syntax
+
+SQLite <br/>
+`strftime('%Y', InvoiceDate` <br/>
+[strftime documentation](https://www.w3resource.com/sqlite/sqlite-strftime.php)

total_sales_{year}.sql

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+SELECT strftime('%Y', InvoiceDate) as Year,
+    SUM(TOTAL) as YearlyTotal
+FROM Invoice
+WHERE strftime('%Y', InvoiceDate) = '2009'
+    OR strftime('%Y', InvoiceDate) = '2011'
+GROUP BY strftime('%Y', InvoiceDate);
+
+SELECT * FROM Invoice;

tracks_no_id.sql

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+SELECT Track.Name AS Track_Name, 
+    Album.Title AS Album_Title, 
+    MediaType.Name AS Media_Type, 
+    Genre.Name AS Genre
+From Track
+INNER JOIN Album
+ON Track.AlbumId = Album.AlbumId
+INNER JOIN MediaType
+ON Track.MediaTypeId = MediaType.MediaTypeId
+INNER JOIN Genre
+ON Track.GenreId = Genre.GenreId;