Introduces a grouping shortcut for unique values, called SELECT DISTINCT, and shows how to combine this with numeric functions
- [Narrator] Now, we've been introduced…to GROUP BY already, and we used this…with count(*) to see which values…were the most popular in a field.…When we run this query, we see…that we have 378 rows returned…even though we know that there are 603 rows…in the table overall.…So what this tells us is…that there are 378 unique values.…Now sometimes, all you need is a list…of those unique values.…And if that's what you're after,…there's a quicker way of doing it.…And that's called SELECT DISTINCT.…
So we could say SELECT DISTINCT district, like so.…And that's giving us, albeit in a different order,…378 unique values from that one field.…Sometimes when you see SELECT DISTINCT written…it's followed by parentheses or brackets…that contain the fieldname like so.…And in MySQL, that works fine with or without.…But what doesn't work is when you're trying…to select a unique combination of fields…which you can do with SELECT DISTINCT.…
So if we tried to put…SELECT DISTINCT(district,address2)…that would throw an error in MySQL…but it would work absolutely fine…
Join Emma Saunders as she shows you how to design and write simple SQL queries for data reporting and analysis. Review the different types of SQL, and then learn how to filter, group, and sort data, using built-in SQL functions to format or calculate results. Learn a bit about data types and database design. Discover how to perform more complex queries, such as joining data together from different database tables. Last but not least, Emma shows how to save your queries as views, so you can run them again and again.
- Using different versions of SQL
- Retrieving data with SELECT statements
- Filtering and sorting your results
- Transforming results with built-in SQL functions
- Grouping SQL results
- Merging data from multiple tables
- Identifying data types, and how to make sense of your database design
- Saving SQL queries
Skill Level Intermediate
1. Use SQL to Report Data
Data types in SQL databases5m 47s
2. Group your SQL Results
3. Merge Data from Multiple Tables
4. Advanced Features and Taking Your Learning Forwards
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