DML 数据操纵语言(select,delete,uqdate,insert)
select 选择
insert 插入 insert into table1(key1,key2) values(val1,val2)
delete 删除
update 更新 update table1 set key1 = val1
like select from table1 where key1 like “%val%”
order by select from order by key1
count select count as name_other from table1
sum select sum(key1) as name_other from table1
avg select avg(key1) as name_other from table1
max select max(key1) as name_other from table1
min select min(key1) as name_other from table1
union 返回两个结果集的并集 select from table1 union select from table2
except 返回两个结果集的差，查询符合左表不符合右表的 select from table1 union select from table2
intersect 返回两个结果集的并集 select from table1 intersect select from table2
left join on 返回连接表的匹配项，也返回左表的所有项 select * from table1 left join table2 on table1.key1 = table2.key2
right join on 返回连接表的匹配项，也返回右表的所有项
full join on 返回连接表所有项
inner join on 返回连接表的共同项
between 限制查询范围，同时包括边界值 select from table1 where time between time1 and time2
not between 反之
in 匹配条件中的任意值 select from table1 where key1 in (val1,val2)
not in 反之
group by 根据某一项或多项对结果进行分组统计 select key1,sum(key2) name_other from table1 group by key1
纯属基础，稍作总结，全属语义，全靠用熟。