SQL学习
- 几个操作时间的函数
1 --datapart 获取时间中的年月日时分秒等部分 2 select DATEPART(year,current_timestamp); 3 select DATEPART(DAY,current_timestamp); 4 select DATEPART(MONTH,current_timestamp); 5 6 --dateadd 在相应时间上加上年月日时分秒等 7 select CURRENT_TIMESTAMP,DATEADD(DAY,10,CURRENT_TIMESTAMP); 8 select DATEADD(month,11,'2001-2-28 12:00:00') as 上帝时刻; 9 10 --datediff 获取两时间段的差值并换算为时分秒年月日等 11 select DATEDIFF(month,'2014-8-3','2015-9-10'); 12 13 --转换函数 转换类型 14 --cast convert 15 16 select '123'+456; 17 select '123'+cast(456 as varchar); 18 select '123'+CONVERT(varchar,456); 19 20 --convert时间类型转换 后面的数字即不同地区的时间表示方式 21 select CURRENT_TIMESTAMP, 22 CONVERT(VARCHAR,CURRENT_TIMESTAMP,111);--中国时间表示 23 24 select CURRENT_TIMESTAMP, 25 CONVERT(VARCHAR,CURRENT_TIMESTAMP,110);--美国时间表示
- 简单练习
1 --练习题 2 use TextDB 3 create table TB_CallRecord 4 ( 5 Id int not null identity(1,1), 6 CallNumber nvarchar(50), 7 TelNum varchar(50), 8 StartDateTime datetime null, 9 EndDateTime datetime null 10 ) 11 --主键约束 12 alter table TB_CallRecord 13 add constraint PK_CallRecord primary key (Id); 14 --检查约束 15 alter table TB_CallRecord 16 add constraint CK_CallRecords check(CallNumber like '[0-9][0-9][0-9]') 17 18 alter table TB_CallRecord 19 add constraint CK_CallRecords_EndDateTime check(EndDateTime > StartDateTime) 20 21 --默认约束 22 alter table TB_CallRecord 23 add constraint DF_CallRecords default(getdate()) for EndDateTime 24 25 26 27 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '0208888888', CAST(0x00009DAF00A4CB80 AS DateTime), CAST(0x00009DAF00A62E94 AS DateTime)); 28 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '0208888888', CAST(0x00009DB000D63BC0 AS DateTime), CAST(0x00009DB000D68DC8 AS DateTime)); 29 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '89898989', CAST(0x00009DB000E85C60 AS DateTime), CAST(0x00009DB000E92F50 AS DateTime)); 30 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('002', '98987676', CAST(0x00009DB2015BB7A0 AS DateTime), CAST(0x00009DB2015C4DA0 AS DateTime)); 31 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('002', '02188839389', CAST(0x00009DA4014C9C70 AS DateTime), CAST(0x00009DA4014E0308 AS DateTime)); 32 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '767676766', CAST(0x00009DB400DAA0C0 AS DateTime), CAST(0x00009DB400DD5FE0 AS DateTime)); 33 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('003', '0227864656', CAST(0x00009DB200B9AB40 AS DateTime), CAST(0x00009DB200B9FC1C AS DateTime)); 34 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('003', '676765777', CAST(0x00009DB8014042B8 AS DateTime), CAST(0x00009DB80141804C AS DateTime)); 35 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '89977653', CAST(0x00009D9A00FB9898 AS DateTime), CAST(0x00009D9A00FE6118 AS DateTime)); 36 INSERT TB_CallRecord ([CallNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('004', '400400400', CAST(0x00009D9A00FB9898 AS DateTime), CAST(0x00009D9A00FE6118 AS DateTime)); 37 38 --查看全表 39 select * from TB_CallRecord; 40 41 --输出通话时间最长的五条记录 42 select top 5 *,DATEDIFF(SECOND,StartDateTime,EndDateTime) as 通话时长 from TB_CallRecord order by DATEDIFF(SECOND,StartDateTime,EndDateTime) DESC; 43 44 --输出所有数据中拨打长途号码（对方号码以0开头）的总时长。like、sum 45 SELECT SUM(DATEDIFF(SECOND,StartDateTime,EndDateTime)) from TB_CallRecord WHERE TelNum like '0%'; 46 47 --输出通话总时长最多的前三个呼叫员的编号。 48 select top 3 Id,DATEDIFF(SECOND,StartDateTime,EndDateTime) as 通话时长 from TB_CallRecord order by DATEDIFF(SECOND,StartDateTime,EndDateTime) DESC; 49 50 --输出本月拨打电话次数最多的前三个呼叫员的编号.group by,count(*) 51 select top 3 CallNumber,Id,StartDateTime From TB_CallRecord where DATEPART(MONTH,StartDateTime) = 7 order by CallNumber DESC; 52 53 54 --表序列化row_number()over(order by 字段) 就是将不连续的表依据某一列值排序 55 select ROW_NUMBER()over(order by Id) as 序列化 ,*from TB_CallRecord;
- 事务
1 --事务：SQL中每一条语句都是一个事务，任何错误都会导致整个事务失败
--语法：
/*
begin transaction
代码
end
*/
2 begin transaction 3 declare @myError int; 4 update TextDB..TB_CallRecord set CallNumber = 0127897789 where CallNumber = '004'; 5 set @myError = (select @@ERROR); 6 update TextDB..TB_CallRecord set CallNumber = '005' where Id = 10; 7 set @myError += (select @@ERROR); 8 if(@myError!=0) 9 begin 10 rollback transaction --回滚当前的操作 11 end 12 else 13 begin 14 commit transaction --执行当前的操作 15 end 16 --事务的特征：如果一个事务满足原子性，持久性，隔离性，一致性，那么这个操作则称为事务。 17 18 19 --begin transaction 20 21 select *from TextDB..TB_CallRecord;
- 存储过程
1 --存储过程 2 --语法： 3 /* 4 create proc[edure] 存储过程名字 5 参数 as 类型 [默认值|out] 6 as 7 begin 8 代码 9 end 10 */ 11 --例如： 12 go 13 create proc usp_text 14 as 15 begin 16 begin transaction 17 declare @myError int; 18 update TextDB..TB_CallRecord set CallNumber = '008' where CallNumber = '004'; 19 set @myError = (select @@ERROR); 20 update TextDB..TB_CallRecord set CallNumber = '005' where Id = 10; 21 set @myError += (select @@ERROR); 22 if(@myError!=0) 23 begin 24 rollback transaction 25 end 26 else 27 begin 28 commit transaction 29 end 30 31 end 32 --执行存储过程 33 exec usp_text; 34 35 select * from TextDB..TB_CallRecord; 36 37 38 --带参数的存储过程 39 go 40 create proc usp_text2 41 @oldnum as nvarchar(50) 42 ,@newnum as nvarchar(50) 43 as 44 begin 45 update TextDB..TB_CallRecord set CallNumber = @newnum where CallNumber = @oldnum; 46 end 47 48 --调用带参数的存储过程 49 exec usp_text2 '005','008'; 50 select * from TextDB..TB_CallRecord 51 52 53 --带参数和返回值的存储过程 54 go 55 create proc usp_text3 56 @oldnum as nvarchar(50) 57 ,@newnum as nvarchar(50) 58 ,@isSuccess int output --使用output将函数内参数抛出给外部 59 as 60 begin 61 declare @myError int 62 update TextDB..TB_CallRecord set CallNumber = @newnum where CallNumber = @oldnum; 63 set @myError = (select @@ERROR); 64 if(@myError=0) 65 begin 66 commit 67 set @isSuccess = 1 68 end 69 else 70 begin 71 rollback 72 set @isSuccess = 0; 73 end 74 end 75 76 --调用带参数和返回值的存储过 77 declare @result int 78 exec usp_text3 '008','004',@result output; 79 select @result; 80 81 --使用try catch 82 go 83 create proc usp_text4 84 @oldnum as nvarchar(50) 85 ,@newnum as nvarchar(50) 86 ,@IsSucess int output 87 as 88 begin 89 begin transaction 90 update TextDB..TB_CallRecord 91 set CallNumber = @newnum 92 where CallNumber = @oldnum 93 begin try 94 commit 95 set @IsSucess = 1; 96 end try 97 begin catch 98 rollback 99 set @IsSucess = 0; 100 end catch 101 end 102 103 --调用带有try，catch的存储过程 104 declare @result int 105 exec usp_text4 '004','007',@result output; 106 select @result;
- 触发器
1 --触发器 2 --语法 3 /* 4 create trigger tr_类型触发器名字 on 表名 5 触发类型：after|instea of 6 操作类型：inser|delete|update 7 as 8 begin 9 代码 10 end 11 */ 12 13 --案例 14 --插入数据的同时获得自动增长的Id 15 select * from TextDB..TB_USER; 16 17 insert INTO TextDB..TB_USER (userID,[password],code,lastTime) 18 OUTPUT inserted.userID 19 VALUES ('aaa','DDD','23','2007-03-12'); 20 21 ----------- 22 go 23 create trigger tr_delete_不会删除的表 on TextDB..TB_USER 24 after 25 delete 26 as 27 insert into TextDB..TB_USER(userID,[password],code,lastTime) 28 select userID,[password],code,lastTime from deleted; 29 go 30 31 32 select * from TextDB..TB_USER; 33 delete TB_USER 34 select SUSER_NAME();
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