Postgres
========

Command to display active connections to a PostgresDB: `SELECT * FROM pg_stat_activity;`

Connection to Redshift
----------------------

```
$ psql -h <ENDPOINT_NAME>.us-east-1.redshift.amazonaws.com -p 5439 -d <DB_NAME> -U <DB_USERNAME>
password <TYPE_YOUR_PASSWORD_HERE>
```

```
\list or \l: list all databases
\dt: list all tables in the current database
\dn: list of schemas
\dt <schema_name>.*: list tables in <schema_name>
\d+ <schema_name>.<table_name>: describe a table in a schema
SET search_path = <schema_name>;
```

To find all the columns with a name like query:
```
select table_name, column_name
from information_schema.columns
where table_schema=<SCHEMA_NAME> and column_name like '%some%thing%';
```

To see output in VERTICAL form:
```
\x # enable vertical output
<your queries>
\x # disable vertical output
```

MySQL
=====

Connection
----------

```
$ mysql -h <HOST_IP> -P 3306 -u <DB_USERNAME> -p -A -D <DB_NAME>
<TYPE_YOUR_PASSWORD_HERE>
```

```
show databases;
use <DB_NAME>;
<YOUR QUERY> \G # the output in VERTICAL form
```

Performing a dump
-----------------

```
$ mysqldump -P 3306 -h <HOST_IP> -u <DB_USERNAME> -p <DB_PASSWORD> <TABLE_NAME> --where="columns='some_value'" > ~/tmp/foo.sql
```