Databases & SQL

2:15 Lesson 1 Databases and SELECT A spreadsheet with fifty thousand rows is where a question goes to die. A database is the same grid, bui… 1:26 Lesson 2 Choosing columns A star gives you every column, and usually you want only a few. So instead of the star, list the ones yo… 1:58 Lesson 3 Filtering with WHERE Every query so far returned all the rows. WHERE changes that: it keeps only the rows that match a condit… 2:05 Lesson 4 AND, OR and NOT A WHERE can test more than one thing. AND requires both to be true. Take form equals eleven A on its own… 1:59 Lesson 5 Sorting with ORDER BY Rows come back in no particular order. It usually LOOKS like insertion order, but nothing promises that,… 2:01 Lesson 6 Counting and averaging Sometimes you do not want the rows, you want a summary of them. An aggregate function does that, and it … 2:04 Lesson 7 LIKE, IN and BETWEEN Sometimes you do not know the exact value — you know the shape of it. LIKE compares against a pattern. H… 2:05 Lesson 8 Grouping with GROUP BY Last lesson an aggregate folded the whole table into one number. Usually you want one number per somethi… 2:07 Lesson 9 Tables, keys and relationships Real databases hold several tables, and the reason is easiest to see by doing it wrong first. Put everyt… 2:03 Lesson 10 INNER JOIN Splitting the data was the right thing to do, but now a question about customers and their orders touche… 1:59 Lesson 11 Joins with grouping Everything in this lesson you have already met. A join makes one wide table. GROUP BY sorts that into pi… 2:09 Lesson 12 Creating tables SQL splits into two halves, and it is worth being able to name them. DDL, the data definition language, … 1:53 Lesson 13 Changing the schema A table's design is not fixed once it is made. ALTER TABLE ADD gives an existing table a new column, nam… 1:58 Lesson 14 Inserting rows A table with no rows in it is a shape, not data. This is the statement that puts something inside it. IN… 2:01 Lesson 15 Updating rows Somebody changes their phone number. You do not want a new row - you want the one that is already there … 1:55 Lesson 16 Deleting rows There is no undo. Every DELETE you will ever write should be a SELECT first. DELETE removes rows. Name t… 2:30 Lesson 17 Normalisation Put every club booking in one table and something goes wrong quietly. Look at the coach column: Mr Ng is…