What is the SQL command to return the field names of a table?

MySQL 3 and 4 (and 5):

desc tablename

which is an alias for

show fields from tablename

SQL Server (from 2000) and MySQL 5:

select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 'tablename'

Completing the answer: like people below have said, in SQL Server you can also use the stored procedure sp_help

exec sp_help 'tablename'

SQL-92 standard defines INFORMATION_SCHEMA which conforming rdbms's like MS SQL Server support. The following works for MS SQL Server 2000/2005/2008 and MySql 5 and above

select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 'myTable'

MS SQl Server Specific:

exec sp_help 'myTable'

This solution returns several result sets within which is the information you desire, where as the former gives you exactly what you want.

Also just for completeness you can query the sys tables directly. This is not recommended as the schema can change between versions of SQL Server and INFORMATION_SCHEMA is a layer of abstraction above these tables. But here it is anyway for SQL Server 2000

select [name] from dbo.syscolumns where id = object_id(N'[dbo].[myTable]')

You can use the provided system views to do this:

eg

select * from INFORMATION_SCHEMA.COLUMNSwhere table_name = '[table name]'

alternatively, you can use the system proc sp_help

eg

sp_help '[table name]'