SELECT sysobjects.name AS [table], sysproperties.[value] AS 表说明,
syscolumns.name AS field, properties.[value] AS 字段说明, systypes.name AS type,
syscolumns.length, ISNULL(COLUMNPROPERTY(syscolumns.id, syscolumns.name,
'Scale'), 0) AS 小数位数, syscolumns.isnullable AS isnull,
CASE WHEN syscomments.text IS NULL
THEN '' ELSE syscomments.text END AS [Default],
CASE WHEN COLUMNPROPERTY(syscolumns.id, syscolumns.name, 'IsIdentity')
= 1 THEN '√' ELSE '' END AS 标识, CASE WHEN EXISTS
(SELECT 1
FROM sysobjects
WHERE xtype = 'PK' AND name IN
(SELECT name
FROM sysindexes
WHERE indid IN
(SELECT indid
FROM sysindexkeys
WHERE id = syscolumns.id AND colid = syscolumns.colid)))
THEN '√' ELSE '' END AS 主键
FROM syscolumns INNER JOIN
sysobjects ON sysobjects.id = syscolumns.id INNER JOIN
systypes ON syscolumns.xtype = systypes.xtype LEFT OUTER JOIN
sysproperties properties ON syscolumns.id = properties.id AND
syscolumns.colid = properties.smallid LEFT OUTER JOIN
sysproperties ON sysobjects.id = sysproperties.id AND
sysproperties.smallid = 0 LEFT OUTER JOIN
syscomments ON syscolumns.cdefault = syscomments.id
WHERE (sysobjects.xtype = 'U') order by sysobjects.name
精度是数字中的数字个数。小数位数是数中小数点右边的数字个数。例如，数123.45 的精度是5，小数位数是2
http://msdn.microsoft.com/zh-tw/library/8kb3ddd4(VS.80).aspx