# Working with the Capsul database

## Running manual database queries

You can manually mess around with the database like this:

```
pipenv run flask cli sql -f test.sql
```

```
pipenv run flask cli sql -c 'SELECT * FROM vms'
```

This one selects the vms table with the column name header:

```
pipenv run flask cli sql -c "SELECT string_agg(column_name::text, ', ') from information_schema.columns WHERE table_name='vms'; SELECT * from vms"
```

How to modify a payment manually, like if you get a chargeback or to fix customer payment issues:

```
$ pipenv run flask cli sql -c "SELECT id, created, email, dollars, invalidated from payments"
1, 2020-05-05T00:00:00, forest.n.johnson@gmail.com, 20.00, FALSE

$ pipenv run flask cli sql -c "UPDATE payments SET invalidated = True WHERE id = 1"
1 rows affected.

$ pipenv run flask cli sql -c "SELECT id, created, email, dollars, invalidated from payments"
1, 2020-05-05T00:00:00, forest.n.johnson@gmail.com, 20.00, TRUE
```

## Database schema management

capsulflask has a concept of a schema version. When the application starts, it will query the database for a table named `schemaversion` that has one row and one column (`version`). If the `version` it finds is not equal to the `desiredSchemaVersion` variable set in `db.py`, it will run  migration scripts from the `schema_migrations` folder one by one until the `schemaversion` table shows the correct version.

For example, the script named `02_up_xyz.sql` should contain code that migrates the database from schema version 1 to schema version 2. Likewise, the script `02_down_xyz.sql` should contain code that migrates from schema version 2 back to schema version 1.

**IMPORTANT: if you need to make changes to the schema, make a NEW schema version. DO NOT EDIT the existing schema versions.**

In general, for safety, schema version upgrades should not delete data. Schema version downgrades will simply throw an error and exit for now. 

## how to view the logs on the database server (legion.cyberia.club)

`sudo -u postgres pg_dump capsul-flask | gzip -9 > capsul-backup-2021-02-15.gz`