select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b
外连接查询(表名1:a 表名2:b)
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c
在线查看查询(表名1:a)
select * from (SELECT a,b,c FROM a) T where t.a > 1;
用法,限制查询数据范围时,边界值包含,不包含
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
如何使用在
select * from table1 where a [not] in (‘值1","值2","值4","值6")
两个相关表,删除主表中子表中没有的信息
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 )
四表联合查询问题
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where .....
提前五分钟安排提醒
SQL: select * from 日程安排 where datediff("minute",f开始时间,getdate())>5
一条sql语句处理数据库分页
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段
关于数据库分页:
declare @start int,@end int @sql nvarchar(600) set @sql="select top"+str(@end-@start+1)+"+from T where rid not in(select top"+str(@str-1)+"Rid from T where Rid>-1)" exec sp_executesql @sql
注意:top后面不能直接跟一个变量,所以在实际应用中,只有这种变量才会被特殊处理。 Rid 是一个识别列。 如果top后面还有特定的字段,这样做是非常有益的。 因为这样可以避免如果top字段是逻辑索引的话,查询结果后与实际表不一致(逻辑索引中的数据可能与数据表不一致,查询时如果在索引中,先查询指数)
前 10 条记录
select top 10 * form table1 where 范围
选取b值相同的每组数据中a最大的记录对应的所有信息(类似用法可用于论坛月度排名、月度热销产品分析、主题表现排名等)
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b)
派生一个结果表,包括所有在其中但不在其中的行,并消除所有重复行
(select a from tableA ) except (select a from tableB) except (select a from tableC)
随机取出10条数据
select top 10 * from tablename order by newid()
随机选择记录
select newid()
删除重复记录
1),delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) 2),select distinct * into temp from tablename delete from tablename insert into tablename select * from temp 评价: 这种操作牵连大量的数据的移动,这种做法不适合大容量的数据操作 3),例如:在一个外部表中导入数据,由于某些原因第一次只导入了一部分,但很难判断具体位置,这样只有在下一次全部导入,这样也就产生好多重复的字段,怎样删除重复字段 alter table tablename --添加一个自增列 add column_b int identity(1,1) delete from tablename where column_b not in( select max(column_b) from tablename group by column1,column2,...) alter table tablename drop column column_b
列出数据库中所有表名
select name from sysobjects where type="U" // U代表用户
列出表中所有列名
select name from syscolumns where id=object_id("TableName")
列表类型,pcs字段,按类型字段排列,case可以方便的实现多选,类似中的case。
select type,sum(case vender when "A" then pcs else 0 end),sum(case vender when "C" then pcs else 0 end),sum(case vender when "B" then pcs else 0 end) FROM tablename group by type
类型 pcs
电脑A 1
电脑A 1
光盘B 2
光盘A 2
手机B 3
手机C 3
初始化表
TRUNCATE TABLE table1
选择 10 到 15 条记录
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc
1=1和1=2的使用技巧常用于SQL语句的组合中
“where 1=1”表示全部选择“where 1=2”全部不选择,
喜欢:
if @strWhere !="" begin set @strSQL = "select count(*) as Total from [" + @tblName + "] where " + @strWhere end else begin set @strSQL = "select count(*) as Total from [" + @tblName + "]" end
我们可以直接写
set @strSQL = "select count(*) as Total from [" + @tblName + "] where 1=1 and "+ @strWhere
收缩数据库
--重建索引 DBCC REINDEX DBCC INDEXDEFRAG --收缩数据和日志 DBCC SHRINKDB DBCC SHRINKFILE
压缩数据库
dbcc shrinkdatabase(dbname)
将数据库传输给具有现有用户权限的新用户
exec sp_change_users_login "update_one","newname","oldname" go
检查备份集
RESTORE VERIFYonLY from disk="E:dvbbs.bak"
修复数据库
ALTER DATAbase [dvbbs] SET SINGLE_USER GO DBCC CHECKDB("dvbbs",repair_allow_data_loss) WITH TABLOCK GO ALTER DATAbase [dvbbs] SET MULTI_USER GO
日志清除
SET NOCOUNT ON DECLARE @LogicalFileName sysname, @MaxMinutes INT, @NewSize INT USE tablename -- 要操作的数据库名 SELECT @LogicalFileName = "tablename_log", -- 日志文件名 @MaxMinutes = 10, -- Limit on time allowed to wrap log. @NewSize = 1 -- 你想设定的日志文件的大小(M) Setup / initialize DECLARE @OriginalSize int SELECT @OriginalSize = size FROM sysfiles WHERE name = @LogicalFileName SELECT "Original Size of " + db_name() + " LOG is " + ConVERT(VARCHAR(30),@OriginalSize) + " 8K pages or " + ConVERT(VARCHAR(30),(@OriginalSize*8/1024)) + "MB" FROM sysfiles WHERE name = @LogicalFileName CREATE TABLE DummyTrans (DummyColumn char (8000) not null) DECLARE @Counter INT, @StartTime DATETIME, @TruncLog VARCHAR(255) SELECT @StartTime = GETDATE(), @TruncLog = "BACKUP LOG " + db_name() + " WITH TRUNCATE_ONLY" DBCC SHRINKFILE (@LogicalFileName, @NewSize) EXEC (@TruncLog) -- Wrap the log if necessary. WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) AND (@OriginalSize * 8 /1024) > @NewSize BEGIN -- Outer loop. SELECT @Counter = 0 WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) BEGIN -- update INSERT DummyTrans VALUES ("Fill Log") DELETE DummyTrans SELECT @Counter = @Counter + 1 END EXEC (@TruncLog) END SELECT "Final Size of " + db_name() + " LOG is " + ConVERT(VARCHAR(30),size) + " 8K pages or " + ConVERT(VARCHAR(30),(size*8/1024)) + "MB" FROM sysfiles WHERE name = @LogicalFileName DROP TABLE DummyTrans SET NOCOUNT OFF
换一张桌子
exec sp_changeobjectowner "tablename","dbo"
存储对所有表的更改
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch @OldOwner as NVARCHAR(128), @NewOwner as NVARCHAR(128) AS DECLARE @Name as NVARCHAR(128) DECLARE @Owner as NVARCHAR(128) DECLARE @OwnerName as NVARCHAR(128) DECLARE curObject CURSOR FOR select "Name" = name, "Owner" = user_name(uid) from sysobjects where user_name(uid)=@OldOwner order by name OPEN curObject FETCH NEXT FROM curObject INTO @Name, @Owner WHILE(@@FETCH_STATUS=0) BEGIN if @Owner=@OldOwner begin set @OwnerName = @OldOwner + "." + rtrim(@Name) exec sp_changeobjectowner @OwnerName, @NewOwner end -- select @name,@NewOwner,@OldOwner FETCH NEXT FROM curObject INTO @Name, @Owner END close curObject deallocate curObject GO
直接在SQL循环中写入数据
declare @i int set @i=1 while @i<30 begin insert into test (userid) values(@i) set @i=@i+1 end
案件:
有下表,要求把不合格的成绩全部框起来,在每次增加0.1的基础上,就通过了:
姓名分数
80
力士59
50
69
while((select min(score) from tb_table)<60) begin update tb_table set score =score*1.01 where score<60 if (select min(score) from tb_table)>60 break else continue end
资料开发-经典按姓氏笔画排序
Select * From TableName Order By CustomerName Collate Chinese_PRC_Stroke_ci_as //从少到多
数据库加密
select encrypt("原始密码") select pwdencrypt("原始密码") select pwdcompare("原始密码","加密后密码") = 1--相同;否则不相同 encrypt("原始密码") select pwdencrypt("原始密码") select pwdcompare("原始密码","加密后密码") = 1--相同;否则不相同
检索表中的字段
declare @list varchar(1000), @sql nvarchar(1000) select @list=@list+","+b.name from sysobjects a,syscolumns b where a.id=b.id and a.name="表A" set @sql="select "+right(@list,len(@list)-1)+" from 表A" exec (@sql)
查看硬盘分区
EXEC master..xp_fixeddrives
比较 A 和 B 表是否相等
if (select checksum_agg(binary_checksum(*)) from A) = (select checksum_agg(binary_checksum(*)) from B) print "相等" else print "不相等"
杀死所有分析器进程
DECLARE hcforeach CURSOR GLOBAL FOR SELECT "kill "+RTRIM(spid) FROM master.dbo.sysprocesses WHERE program_name IN("SQL profiler",N"SQL 事件探查器") EXEC sp_msforeach_worker "?"
从头记录查找到N条记录
Select Top N * From 表
N到M条记录(带有主索引ID)
Select Top M-N * From 表 Where ID in (Select Top M ID From 表) Order by ID Desc
N 到结束记录
Select Top N * From 表 Order by ID Desc
案子
例1:某表有10000多条记录,表的第一个字段RecID为自增字段。 编写一条SQL语句查找表中的第31条到第40条记录。
来自 A 的前 10 个记录,其中记录不在其中(来自 A 的前 30 个记录)
分析:这样写的话,会出现一些问题,如果表中有recid的逻辑索引。
A where... 的前 10 个 reci 是从索引中查找的,而 A 的前 30 个 reci 是在数据表中查找的,所以索引中的顺序可能与数据表中的顺序不一致,从而导致query 不是原来想要的数据。
解决方案
例2:查询表中最后一条记录,但不知道这张表有多少数据和表结构。
set @s = ' top 1 * from T where pid not in ( top " + str(@count-1) + " pid from T)"
打印@s 执行@s
获取当前数据库所有用户表
select Name from sysobjects where xtype="u" and status>=0
获取表的所有字段
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")
两种方式效果相同
查看与表相关的视图、存储过程和函数
select a.* from sysobjects a, syscomments b where a.id = b.id and b.text like "%表名%"
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"
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
查询表的字段和数据类型
select column_name,data_type from information_schema.columns where table_name = "表名"
SQL基本函数用于不同服务器数据库之间的数据操作
SQL基本函数
字符串函数
长度和分析
常识
以上就是小编为大家介绍的SQL数据库语句全集,希望对大家有所帮助。 非常感谢您对云海天教程网站的支持!