Join Sheeri Cabral for an in-depth discussion in this video Querying dynamic columns, part of Understanding MariaDB for MySQL Users.
…Now that we have made some dynamic columns,…how can we see what is inside them?…MariaDB provides a COLUMN_GET function,…which takes in a dynamic column name and a part name and returns the value.…There's one catch however MariaDB does not assume to…know the data type of the values in your dynamic columns.…So you have to explicitly set them.…COLUMN_GET takes in a dynamic column name and a part name, but…you have to specify what the data type is.…
Lets go back to our quarry window.…For example, if we want to find out the rating of the sampled DVD,…we would quarry, SELECT COLUMN_GET extra,…rating, as a CHAR type.…FROM items.…WHERE title equals Sample DVD.…And we can see that it did indeed return that our rating for this movie is P-G.…If you use the COLUMN_GET function in a dynamic column, but…the column does not have that column part.…
You will get null.…Let's try to get a rating for the open SQL camp t-shirt.…So we'll just change the WHERE clause from where title equals Sample DVD…to WHERE type equals T-shirt.…
- Why use dynamic columns?
- Creating, updating, and querying dynamic columns
- Installing the CONNECT storage engine
- Connecting to remote data
- Connecting to CSV, INI, and XML files
- Using PIVOT tables
- Accessing database metadata
- Working with the Cassandra storage engine
Skill Level Intermediate
Ruby on Rails 4 Essential Trainingwith Kevin Skoglund12h 41m Beginner
1. Dynamic Columns
2. The Power of CONNECT
3. Advanced CONNECT Storage Engine
4. The Cassandra Storage Engine
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