查询实例：
1.select * from asset,class where asset.sum=class.class_id
2.select * from asset where name like '%电%' order by id desc
3.select * from asset where name=''
4.select * from asset where name<>''
5.select * from asset where sum is not null
6.select * from asset where sum is null 'null不等于''
7.select * from asset where dat>#2001-7-20#
8.select max(sum) as 最大值,min(sum) as 最小值,sum(sum) as 总和,avg(sum) as 平均值,count(sum) as 记录数,count(*) as 总记录数 from asset
9.select * from asset where name like '__' '找两个字符的记录
10.select * from asset where name like '%电%' and name like '%脑%'
增加，修改，删除实例：
1.insert into asset(name,sum,dat,pass) values('电器',24,#2001-8-8#,1)
2.update asset set pass=0 where pass=1
3.delete from asset where name='电视' and pass=true
创建,删除,增加字段实例：
1.CREATE TABLE test (数字 int NOT NULL,文本 text (250),日期 datetime,备注 memo,是否 bit,primary key(数字))
2.DROP TABLE test '删除表
3.ALTER TABLE test ADD sum int,tt text (50) '增加字段sum和tt