Microsoft SQL

- desc [table name] (cf. http://www.electrictoolbox.com/describe-table-structure-sql-server/ )
exec sp_columns [table name]

- select * from [table name] limit [n] (cf. http://stackoverflow.com/questions/603724/how-to-implement-limit-with-microsoft-sql-server )
select top [n] * from [table name] 

- show tables (cf. http://www.webmasterworld.com/forum112/142.htm )
select name from [database name]..sysobjects where xtype='U';