![]() Using io.Handling CSV files with wide columns in Python.Python CLI utility and library for manipulating SQLite databasesĪn open source multi-tool for exploring and publishing dataĭatasette plugin providing an automatic GraphQL API for your SQLite databasesįunctions for finding numbers using higher/lowerĭownload map tiles and store them in an MBTiles database Preview of new JSON default format for Datasette I really liked that, so I’ve implemented it here as well.Įach entry (and quotation and link) now gets a block in the sidebar that looks like this:Īs a long-time fan of faceted search interfaces I really like this upgrade-it helps indicate at a glance the kind of content I have stashed away in my blog’s archive. I noticed that Will Larson’s blog shows little numbers next to the tags indicating how many times they have been used. This defaults to returning results as a JSON array, but you can add -csv or -tsv or other options to get the results back in different output formats. $ sqlite-utils first.db -attach second second.db ' select * from table_in_first union all select * from second.table_in_second ' ![]() Here’s an illustrative example query that performs a UNION across the sqlite_master metadata table in two databases: The demo now exposes two databases using this feature. Run Datasette with the new -crossdb option and the first ten databases passed to Datasette will be ATTACHed to an in-memory database available at the /_memory URL. In the end, I decided on the simplest option that would unlock the feature. It took me quite a while to settle on a design-SQLite defaults to only allowing ten databases to be attached together, and I needed to figure out how multiple connected databases would fit with the design of the rest of Datasette. I’ve wanted to add support for cross-database queries to Datasette since May 2018. You can then join against them, combine them with UNION and generally treat them as if they were another table in your first connected database. It will be created as a column that allows NULL values. For example: ALTER TABLE employees ADD status VARCHAR This SQLite ALTER TABLE example will add a column called status to the employees table. Run the following SQL: ATTACH 'other.db' AS other Īnd now you can reference tables in that database as other.tablename. Lets look at an example that shows how to add a column in a SQLite table using the ALTER TABLE statement. The secret sauce is the ATTACH DATABASE command. All you need is a disk volume you can create as many SQLite databases as you like.Ī lesser known feature of SQLite is that you can run queries, including joins, across tables from more than one database. I really love this characteristic-it makes them easy to create, copy and move around. SQLite databases are single files on disk. I released Datasette 0.55 and sqlite-utils 3.6 this week with a common theme across both releases: supporting cross-database joins. The following query gets data from the tracks, albums, media_types and genres tables in the sample database using the inner join clause.Cross-database queries in SQLite (and weeknotes) 1) Creating a view to simplify a complex query Let’s take some examples of creating a new view using the CREATE VIEW statement. However, you can assign the names of the view columns that are different from the column name of the table ![]() By default, the columns of the view derive from the result set of the SELECT statement. Third, specify a SELECT statement for the view. The view is called a temporary view and SQLite automatically removes the temporary view whenever the database connection is closed. Second, use the the TEMP or TEMPORARY option if you want the view to be only visible in the current database connection. If the view already exists, it does nothing. The IF NOT EXISTS option only creates a new view if it doesn’t exist. CREATE VIEW view_nameĪS select- statement Code language: SQL (Structured Query Language) ( sql )įirst, specify a name for the view. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |