>>mysql:
1、查看所有表名：
show tables [from db_name];
2、查看字段信息
SHOW FULL COLUMNS from db_name.table_name
获取以下信息
Field ：字段名
Type：字段类型
Collation：字符集 （mysql 5.0以上有）
Null ：是否可以为NULL
Key：索引（PRI,unique,index)
Default：缺省值
Extra：额外（是否 auto_increment)
Privileges：权限
Comment：备注（mysql 5.0以上有)
>>sqlserver
1、查看所有用户建表名
select name from Sysobjects where xtype='U' order by name;
2、查看字段信息
SELECT
a.colorder as 字段顺序号,
a.name as 字段名称,
a.collation as 排序字符集,
是否自动增长数字=case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then 'yes'else 'no' end,
是否主键=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 = a.id AND colid=a.colid
))) then 'yes' else 'no' end,
字段类型=b.name,
字段长度=a.length,
字段字符长度=COLUMNPROPERTY(a.id,a.name,'PRECISION'),
小数位数=isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0),
是否为NULL=case when a.isnullable=1 then 'yes'else 'no' end,
缺省值=isnull(e.text,'')
from syscolumns a
left join systypes b on a.xtype=b.xusertype
inner join sysobjects d on a.id=d.id and (d.xtype='U' or d.xtype='V') and d.name<>'dtproperties'
left join syscomments e on a.cdefault=e.id
where d.name='purchase_medicine'
order by a.colorder
