The field represented by xtype in the system table syscolumns in sql

select name,xtype from syscolumns where 
                    id=(select id from sysobjects 
                    where name='tab_AAA' and xtype = 'U') and 
                    ((COLUMNPROPERTY(OBJECT_ID('tab_AAA','U'),NAME,'IsIdentity') <> 1) 
                    and (COLUMNPROPERTY(OBJECT_ID('tab_AAA', 'U'),NAME,'IsComputed') <> 1))

xtype    类型
34 image
35 text
36 uniqueidentifier
48 tinyint
52 smallint
56 int
58 smalldatetime
59 real
60 money
61 datetime
62 float
98 sql_variant
99 ntext
104 bit
106 decimal
108 numeric
122 smallmoney
127 bigint
165 varbinary
167 varchar
173 binary
175 char
189 timestamp
231 sysname
231 nvarchar
239 nchar