116 lines
2.1 KiB
Markdown
116 lines
2.1 KiB
Markdown
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# SQLite3
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Creating a reference for SQLite that I can access when I'm offline
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(e.g. traveling in an airplane).
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## Benefits
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I enjoy using SQLite because it's lightweight and simple. Instead of networking
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microservices, I can oftentimes just create a simple `db.sqlite3` file and get
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significant mileage without much tooling overhead.
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## Limitations
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SQLite has some limitations; here are some of the limitations that I have encountered.
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- SQLite **disables** support for `FOREIGN KEY` by default. Enable it with:
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```
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sqlite> PRAGMA foreign_keys = ON;
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```
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- SQLite has no `BOOLEAN` type; it uses 0 and 1 instead.
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```
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sqlite> SELECT TRUE;
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TRUE
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----------
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1
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sqlite> SELECT FALSE;
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FALSE
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----------
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0
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```
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- SQLite has no `DATETIME` type; it uses `TEXT` instead.
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```
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sqlite> SELECT datetime('now');
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datetime('now')
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-------------------
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2020-07-26 09:52:32
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```
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## Reference
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The following should serve as a useful reference for working with SQLite.
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### Schema
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```sql
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CREATE TABLE IF NOT EXISTS Movies (
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title TEXT NOT NULL,
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year INTEGER,
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PRIMARY KEY (title)
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);
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ALTER TABLE Movies ADD COLUMN rating DEFAULT 0.0;
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DROP TABLE Movies;
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```
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### Queries
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The following queries should come in handy as a reference:
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```
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sqlite> -- I'm using an intentionally incorrect date here for the subsequent UPDATE.
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sqlite> INSERT INTO Movies (title, year) VALUES ('Toy Story 3', 2100);
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sqlite> SELECT * FROM Movies WHERE year IS NULL;
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sqlite> UPDATE Movies SET year = 2010 WHERE title = 'Toy Story 3';
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sqlite> -- % is like .* in a regex
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sqlite> DELETE FROM Movies WHERE title LIKE 'Toy Story%';
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```
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## Command Line
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- Create a `~/.sqliterc` file with the following contents:
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```
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.mode column
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.headers on
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```
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- To start an interactive session:
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```shell
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$ sqlite3 db.sqlite3
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```
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- To create a SQLite database from a `.sql` file:
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```shell
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$ sqlite3 db.sqlite3 <db.sql
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```
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- To reload changes to a `.sql` file while in an interactive session:
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```
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sqlite> .read db.sql
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```
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## Miscellaneous
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- For a web-browser-based SQLite viewer, run the following:
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```shell
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$ sqlite_web db.sqlite3
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```
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- To import a CSV:
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```
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sqlite> .mode csv <table-name>
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sqlite> .import path/to/file.csv <table-name>
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```
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