1、说明：增加、删除一个列
Alter table tablename add columnName col type
alter table tablename drop columnName column_b
2.添加删除主键
alter table tableName add constraint PK_Name primary key(Name)
alter table tableName drop constraint PK_Name
3、说明：创建视图、删除视图
create view viewname as select statement
drop view viewname
4、说明：几个简单的基本的sql语句
选择：select * from table1 where范围
插入：insert into table1(field1,field2) values(value1,value2)
删除：delete from table1 where 范围
更新：update table1 set field1=value1 where范围
查找：select * from table1 where field1 like ’%value1%’ ---like的语法很精妙，查资料!
排序：select * from table1 order by field1,field2 [desc]
总数：select count as totalcount from table1
求和：select sum(field1) as sumvalue from table1
平均：select avg(field1) as avgvalue from table1
最大：select max(field1) as maxvalue from table1
最小：select min(field1) as minvalue from table1

5.A： UNION 运算符
UNION 运算符通过组合其他两个结果表（例如 TABLE1 和 TABLE2）并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时（即 UNION ALL）不消除重复行。两种情况下，派生表的每一行不是来自 TABLE1 就是来自 TABLE2。
B： EXCEPT 运算符
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL)，不消除重复行。
C： INTERSECT运算符
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当ALL随 INTERSECT 一起使用时 (INTERSECT ALL)，不消除重复行。

6.说明：复制表(只复制结构,源表名：a 新表名：b) (Access可用)
法一：select * into b from a where 1<>1（仅用于SQlServer）
法二：select top 0 * into b from a

1. 说明：跨数据库之间表的拷贝
   eg:insert into stuDB.dbo.amount select * from 北风贸易.dbo.amount where nickname in ('1','2')

8、说明：在线视图查询(表名1：a )
select * from (SELECT a,b,c FROM a) T where t.a > 1;

9、说明：between的用法,between限制查询数据范围时包括了边界值,not between不包括
select * from table1 where time between time1 and time2
select a,b,c, from table1 where a not between 数值1 and 数值2

10、说明：in 的使用方法
select * from table1 where a [not] in (‘值1’,’值2’,’值4’,’值6’)

11、说明：日程安排提前五分钟提醒
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5

12.按姓氏笔画排序:
Select * From TableName Order By CustomerName Collate Chinese_PRC_Stroke_ci_as //从少到多

13、说明：选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.)
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b)

14、说明：随机取出10条数据
select top 10 * from tablename order by newid()

15、说明：随机选择记录
select newid()

16、说明：删除重复记录
1),delete from tablename where id not in (select max(id) from tablename group by col1,col2,...)（有待考证）
2),select distinct * into temp from tablename
delete from tablename
insert into tablename select * from temp

查询一个数据库里有多少张表
select COUNT(1) from sysobjects where type='U'
select COUNT(1) from information_schema.tables where TABLE_TYPE='BASE TABLE'

17、说明：列出数据库里所有的表名
select name from sysobjects where type='U' // U代表用户

18、说明：列出表里的所有的列名
select name from syscolumns where id=object_id('表名')
select name from syscolumns where id in (select id from sysobjects where type = 'u' and name = '表名')
两种方式的效果相同
查询表结构
SELECT col.name AS columnName ,
t.name AS dataType,
ISNULL(ep.[value], '') AS columnComment ,
CASE WHEN EXISTS (
SELECT 1 FROM dbo.sysindexes si
INNER JOIN dbo.sysindexkeys sik ON si.id = sik.id AND si.indid = sik.indid
INNER JOIN dbo.syscolumns sc ON sc.id = sik.id AND sc.colid = sik.colid
INNER JOIN dbo.sysobjects so ON so.name = si.name AND so.xtype = 'PK'
WHERE sc.id = col.id AND sc.colid = col.colid ) THEN 'PRI'
ELSE ''
END AS columnKey,
CASE WHEN COLUMNPROPERTY(col.id, col.name, 'IsIdentity') = 1 THEN 'auto_increment' ELSE '' END AS extra
FROM dbo.syscolumns col
LEFT JOIN dbo.systypes t ON col.xtype = t.xusertype
inner JOIN dbo.sysobjects obj ON col.id = obj.id AND obj.xtype = 'U' AND obj.status >= 0
LEFT JOIN dbo.syscomments comm ON col.cdefault = comm.id
LEFT JOIN sys.extended_properties ep ON col.id = ep.major_id AND col.colid = ep.minor_id AND ep.name = 'MS_Description'
LEFT JOIN sys.extended_properties epTwo ON obj.id = epTwo.major_id AND epTwo.minor_id = 0 AND epTwo.name = 'MS_Description'
WHERE obj.name = 'InspectionPlanList'--表名
ORDER BY col.colorder ;

19：查看与某一个表相关的视图、存储过程、函数
select a.* from sysobjects a, syscomments b where a.id = b.id and b.text like '%表名%'

20：查看当前数据库中所有存储过程
select name as 存储过程名称 from sysobjects where xtype='P'

21：查询用户创建的所有数据库
select * from master..sysdatabases D where sid not in(select sid from master..syslogins where name='sa')
或者
select dbid, name AS DB_NAME from master..sysdatabases where sid <> 0x01

22：查询某一个表的字段和数据类型
select column_name,data_type from information_schema.columns
where table_name = '表名'

eg:写一个SQL语句， 找出表的第31到第40个记录。
select top 10 recid from A where recid not in(select top 30 recid from A)

23.字符串函数 长度与分析用
1,datalength(Char_expr) 返回字符串包含字符数,但不包含后面的空格
2,substring(expression,start,length) 取子串，字符串的下标是从“1”，start为起始位置，length为字符串长度，实际应用中以len(expression)取得其长度
3,right(char_expr,int_expr) 返回字符串右边第int_expr个字符，还用left于之相反
4,isnull( check_expression,replacement_value)如果check_expression為空，則返回replacement_value的值，不為空，就返回check_expression字符操作类

24.写SQL进行排序的时候我们可能按照username进行排序，我们可能按照名字的拼音、比划及偏旁部首进行排序，Oracle刚好提供了这样的一个函数nlssort（）
NLSSORT()，用来进行语言排序
拼音
SELECT * FROM TEAM ORDER BY NLSSORT(排序字段名,'NLS_SORT = SCHINESE_PINYIN_M')
笔划
SELECT * FROM TEAM ORDER BY NLSSORT(排序字段名,'NLS_SORT = SCHINESE_STROKE_M')
部首
SELECT * FROM TEAM ORDER BY NLSSORT(排序字段名,'NLS_SORT = SCHINESE_RADICAL_M')

25.产生随机数，三种方式都可以
select dbms_random.value from dual
select dbms_random.random from dual
select sys_guid() from dual
26.select to_date('2016/12/15 9:23:48','yyyy/MM/dd hh24:mi:ss ') from dual
27.http://blog.sina.com.cn/s/blog_4ce36a780101b1rl.html oracle时间转换及获取
28.Oracle获取表结构
select COLUMN_NAME,DATA_TYPE,DATA_LENGTH from user_tab_cols where table_name='表名' （表名字母必须全部大写）
27.文字转换，时间转为短日期格式
select xbm=
case
when xbm='1' then '男'
when xbm='2' then '女'
end,
csrq=CONVERT(varchar(12),csrq,111)
from student
28.sql Server中和Oracle的RowNum作用相同
Row_ID=ROW_NUMBER() OVER(ORDER BY (SELECT 1))
row_number() over(order by Displayname) as RowNum
29.标量的使用
declare @count int
select top 100 @count=COUNT(*) from RenYuan_BaseInfo
select @count
30.排名
SELECT 姓名,成绩,
ROW_NUMBER() OVER(ORDER BY 成绩 DESC) AS [ROW_NUMBER],
RANK() OVER(ORDER BY 成绩 DESC) AS [RANK],
DENSE_RANK() OVER(ORDER BY 成绩 DESC) AS [DENSE_RANK],
NTILE(6) OVER(ORDER BY 成绩 DESC) AS [NTILE]
FROM @table

31.Oracle时间比较
SELECT * FROM SR_Punish_CaseInfo WHERE to_char(registerdate,'yyyy-mm-dd') = '2016-09-09'
select * from SR_Punish_CaseInfo WHERE trunc(registerdate)＝to_date('2016-09-09','yyyy-mm-dd') 、
32.行转列
select WM_CONCAT(to_char(itemtext ||'='|| itemvalue)) as aa from code_items where codeid= (select codeid from code_main where codename='听证会方式' )
33.字符串拼接
select cheifsupengineer || '的结构是：'|| structtype 介绍 from zljd_yanshoutz
34.Oracle时间
to_date('2013-10-10 13:13:13','yyyy-mm-dd hh24:mi:ss') 长日期
to_date('2011/01/01','yyyy/mm/dd') 端日期
sysdate 系统日期

1. 分组统计数量
   select AddUserName,sum(case LowProtectionType when '残疾' then 1 else 0 end) '残疾',sum(case LowProtectionType when '受灾' then 1 else 0 end) '受灾',sum(case LowProtectionType when '大病' then 1 else 0 end) '大病' FROM LowProtectionInfo group by AddUserName

36.比较A,B表数据是否相等
if (select checksum_agg(binary_checksum()) from A)
=
(select checksum_agg(binary_checksum()) from B)
print '相等'c
print '不相等'
37.获取当天的数据
select * from Art_News_JRZB where Convert(varchar(100),ZBDate,23)=Convert(varchar(100),GETDATE(),23)
38.Oracle排序，AuditStatus是条件,后面的0,1是排列顺序
http://blog.csdn.net/weeknd/article/details/71157044 decode函数的使用
string OrderBy = " decode(Status,'2',0),decode(Status,'3',1),Row_id desc";
39.NVL(eExpression1, eExpression2)
如果 eExpression1 的计算结果为 null 值，则 NVL( ) 返回 eExpression2。如果 eExpression1 的计算结果不是 null 值，则返回 eExpression1。eExpression1 和 eExpression2 可以是任意一种数据类型。如果 eExpression1 与 eExpression2 的结果皆为 null 值，则 NVL( ) 返回 .NULL.。
40.执行SQL语句块，eg2带有参数
DECLARE @sid NVARCHAR(20)
SET @sid='84121'
DECLARE @selectSQL NVARCHAR(3000)
SET @selectSQL='SELECT * FROM dbo.aa WHERE sid LIKE ''%'+@sid+'%'''
PRINT @selectSQL
exec sp_executesql @selectSQL

eg2:DECLARE @district NVARCHAR(20)
SET @District='三水燃气'
DECLARE @SQL NVARCHAR(3000)
SET @SQL='SELECT ObjectID,SID,District,{0} FROM dbo.aa WHERE District = ''{1}'''
SET @SQL= REPLACE(@SQL,'{0}','thick')
SET @SQL= REPLACE(@SQL,'{1}',@District)
PRINT @SQL
exec sp_executesql @SQL
41.统计数据库中每张表的大小
create table tmp
(
name varchar(50),
rowscount int,
reserved varchar(50),
data varchar(50),
index_size varchar(50),
unused varchar(50)
);
insert tmp(name, rowscount, reserved, data, index_size, unused)
exec sp_MSforeachtable @command1="sp_spaceused '?'";
select * from tmp where name <> 'tmp' order by name
drop table tmp ;