查询表字段信息

string sql = string.Format(@"
                            SELECT
                                syscolumns.colid,
                                Sysobjects.name AS [TableName],
                                syscolumns.name AS [ColumnName],
                                systypes.name AS [DataType],
                                syscolumns.length AS [DataLength],
                                sys.extended_properties.[value] AS [Description],  
                                syscomments.text AS [DefaultValue],
                                syscolumns.isnullable AS [NullAble]    
                            FROM
                                syscolumns INNER JOIN systypes
                                ON syscolumns.xtype = systypes.xtype
                                LEFT JOIN sysobjects ON syscolumns.id = sysobjects.id
                                LEFT OUTER JOIN sys.extended_properties ON
                                ( sys.extended_properties.minor_id = syscolumns.colid
                                AND sys.extended_properties.major_id = syscolumns.id)
                                LEFT OUTER JOIN syscomments ON syscolumns.cdefault = syscomments.id
                            WHERE syscolumns.id IN
                            (SELECT id FROM SYSOBJECTS WHERE xtype = 'U' AND NAME = '{0}') AND (systypes.name <> 'sysname')
                            ORDER BY syscolumns.colid", tbName);