add import/export docs for sqlite

docs/import-and-export-data/postresql.md

@@ -1,106 +1,55 @@
-# Importing and exporting data with PostgreSQL
+# Importing and exporting data with SQLite
 
-This document describes how you can export data from and import data into a PostgreSQL database. You can learn more about this topic in the official [PostgreSQL docs](https://www.postgresql.org/docs/9.1/backup-dump.html).
+This document describes how you can export data from and import data into a SQLite database. You can learn more about this topic in the official [SQLite docs](https://www.sqlitetutorial.net/sqlite-dump/).
 
-## Data export with SQL Dump
+## Data export with `sqlite3`
 
-[SQL Dump](https://www.postgresql.org/docs/9.1/backup-dump.html) is a native PostgreSQL utility you can use to export data from your PostgreSQL database. To see all the options for this command, run `pg_dump --help`.
+[`sqlite3`](https://www.sqlite.org/cli.html) is a native SQLite command line utility you can use for various workflows accross your SQLite database. To see all the options for this command, run `sqlite3 --help`. Exporting data is typically done with the `.dump` command within the `sqlite3` prompt.
 
-From the PostgreSQL docs: 
+To export data, you need to enter the `sqlite3` prompt and point it to the location of your SQLite database file (ends on `.db`):
 
-> The idea behind this dump method is to generate a text file with SQL commands that, when fed back to the server, will recreate the database in the same state as it was at the time of the dump. PostgreSQL provides the utility program `pg_dump` for this purpose. 
-> `pg_dump` is a regular PostgreSQL client application (albeit a particularly clever one). This means that you can perform this backup procedure from any remote host that has access to the database. But remember that pg_dump does not operate with special permissions. In particular, it must have read access to all tables that you want to back up, so in practice you almost always have to run it as a database superuser.
-
-The command looks like this:
-
-```psql
-pg_dump DB_NAME > OUTPUT_FILE
 ```
-
-You need to replace the `DB_NAME` and `OUTPUT_FILE` placeholders with the respective values for: 
-
-- your **database name**
-- the name of the desired **output file** (should end on `.sql`)
-
-For example, to export data from a local PostgreSQL server from a database called `mydb` into a file called `mydb.sql`, you can use the following command:
-
+sqlite3 ./dev.db
 ```
-pg_dump mydb > mydb.sql
-```
-
-If your database schema uses [Object Idenfitifier Types](https://www.postgresql.org/docs/8.1/datatype-oid.html) (OIDs), you'll need to run `pg_dump` with the `--oids` (short: `-o`) option: `pg_dump mydb --oids > mydb.sql`.
-
-#### Providing database credentials
-
-You can add the following arguments to specify the location of your PostgreSQL database server:
-
-| Argument | Default | Env var | Description |  
-| --- | --- | --- | --- |
-| `--host` (short: `-h`) | `localhost` | `PGHOST` | The address of the server's host machine | 
-| `--port` (short: `-p`) | - | `PGPORT` | The port of the server's host machine where the PostgreSQL server is listening | 
-To authenticate against the PostgreSQL database server, you can use the following argument:
 
-| Argument | Default | Env var | Description |  
-| --- | --- | --- | --- |
-| `--username` (short: `-U`) | _your current operating system user name_ | `PGUSER` | The name of the database user. | 
-
-For example, if you want to export data from a PostgerSQL database that has the following [connection string](../core/connectors/postgresql):
+Once you're in the prompt, you can export data as follows:
 
 ```
-postgresql://opnmyfngbknppm:XXX@ec2-46-137-91-216.eu-west-1.compute.amazonaws.com:5432/d50rgmkqi2ipus
+sqlite> .output ./backup.sql
+sqlite> .dump
+sqlite> .exit
 ```
 
-You can use the following `pg_dump` command:
+Alternatively, you can export a specific table by adding the table name after the `.dump` command in the prompt. For example the following command only dumps the `users` table:
 
 ```
-pg_dump --host ec2-46-137-91-216.eu-west-1.compute.amazonaws.com --port 5432 --user opnmyfngbknppm d50rgmkqi2ipus > backup.sql
+sqlite> .output ./backup_users.sql
+sqlite> .dump users
+sqlite> .exit
 ```
 
-Note that **this command will trigger a prompt where you need to specify the password** for the provided user.
-
-#### Controlling the output
-
-There might be cases where you don't want to dump the _entire_ database, for example you might want to:
-
-- dump only the actual data but exclude the [DDL](https://www.postgresql.org/docs/8.4/ddl.html) (i.e. the SQL statements that define your database schema like `CREATE TABLE`,...)
-- dump only the DDL but exclude the actual data
-- exclude a specific PostgreSQL schema
-- exclude large files
-- exclude specic tables
-
-Here's an overview of a few command line options you can use in these scenarios:
-
-| Argument | Default | Description |  
-| --- | --- | --- |
-| `--data-only` (short: `-a`) | `false` | Exclude any [DDL](https://www.postgresql.org/docs/8.4/ddl.html) statements and export only data. | 
-| `--schema-only` (short: `-s`) | `false` | Exclude data and export only [DDL](https://www.postgresql.org/docs/8.4/ddl.html) statements. | 
-| `--blobs` (short: `-b`) | `true` unless either `-schema`, `--table`, or `--schema-only` options are specified | Include binary large objects. | 
-| `--no-blobs` (short: `-B`) | `false` | Exclude binary large objects. | 
-| `--table` (short: `-t`) | _includes all tables by default_ | Explicitly specify the names of the tables to be dumped. | 
-| `--exclude-table` (short: `-T`) | - | Exclude specific tables from the dump. | 
-
-## Importing data from SQL files
-
-After having used SQL Dump to export your PostgreSQL database as a SQL file, you can restore the state of the database by feeding the SQL file into [`psql`](https://www.postgresql.org/docs/9.3/app-psql.html):
+If you want to exclude all data and only export the _database schema_ ([DDL](https://en.wikipedia.org/wiki/Data_definition_language)), you can use `.schema` instead of `.dump`:
 
 ```
-psql DB_NAME < INPUT_FILE
+sqlite> .output ./backup_schema.sql
+sqlite> .schema
+sqlite> .exit
 ```
 
-You need to replace the `DB_NAME` and `INPUT_FILE` placeholders with the respective values for: 
+## Importing data from SQL files
 
-- your **database name** (a database with hat name must be created beforehand!)
-- the name of the target **input file** (likely ends on `.sql`)
+After having used the `.dump` command insinde the `sqlite3` prompt to export your SQLite database as a SQL file, you can restore the state of the database by feeding the SQL file back into `sqlite3` using the `.read` command.
 
-For example:
+Before you can use the `.read` command, you need to enter the `sqlite3` prompt and point it to your SQLite database file:
 
 ```
-psql mydb < mydb.sql
+sqlite3 ./restore.db
 ```
 
-To create the database `DB_NAME` beforehand, you can use the [`template0`](https://www.postgresql.org/docs/9.5/manage-ag-templatedbs.html) (which creates a plain user database that doesn't contain any site-local additions):
+Now you can import the data from your SQL files as follows:
 
-```sql
-CREATE DATABASE dbname TEMPLATE template0;
+```
+.read ./backup.sql
+.exit
 ```