面试题 数据库sql
一、建表的结构和数据，在sqlserver直接用就行了
USE [test]
GO
/****** Object: Table [dbo].[TEACHER] Script Date: 05/16/2018 16:27:24 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[TEACHER](
[T#] [int] NOT NULL,
[TNAME] [nvarchar]() NOT NULL,
PRIMARY KEY CLUSTERED
(
[T#] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'李冰冰')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'黄一山')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'陈小春')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'赵铁柱')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'钱中书')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'孙悟空')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'李连杰')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'杨千嬅')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'泽日生')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'林夕')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'陈奕迅')
INSERT [dbo].[TEACHER] ([T#], [TNAME]) VALUES (, N'刘备')
/****** Object: Table [dbo].[STUDENT] Script Date: 05/16/2018 16:27:24 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[STUDENT](
[S#] [int] NOT NULL,
[SNAME] [nvarchar]() NOT NULL,
[SAGE] [int] NOT NULL,
[SSEX] [char]() NOT NULL,
PRIMARY KEY CLUSTERED
(
[S#] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小红', , N'女')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小明', , N'男')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小绿', , N'男')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小蓝', , N'男')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小青', , N'男')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小白', , N'女')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小紫', , N'女')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小黄', , N'男')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小粉', , N'女')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小橙', , N'女')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小黑', , N'男')
INSERT [dbo].[STUDENT] ([S#], [SNAME], [SAGE], [SSEX]) VALUES (, N'小粉', , N'男')
/****** Object: Table [dbo].[SC] Script Date: 05/16/2018 16:27:24 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[SC](
[S#] [int] NULL,
[C#] [nvarchar]() NULL,
[SCORE] [int] NOT NULL
) ON [PRIMARY]
GO
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
GO
print 'Processed 100 total records'
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
INSERT [dbo].[SC] ([S#], [C#], [SCORE]) VALUES (, N'', )
/****** Object: Table [dbo].[COURSE] Script Date: 05/16/2018 16:27:24 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[COURSE](
[C#] [int] NOT NULL,
[CNAME] [nvarchar]() NOT NULL,
[T#] [nvarchar]() NOT NULL,
PRIMARY KEY CLUSTERED
(
[C#] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'语文1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'语文2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'数学1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'数学2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'英语1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'英语2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'生物1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'生物2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'物理1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'物理2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'化学1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'化学2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'政治1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'政治2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'历史1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'历史2', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'地理1', N'')
INSERT [dbo].[COURSE] ([C#], [CNAME], [T#]) VALUES (, N'地理2', N'')
二、表的数据截图
1、学生表 ：学号、姓名、姓别
2、教师表：编号，名称
3、课程表：课程编号、课程、老师编号
4、分数表：学号、课程号、分数
5、数据准备好后正式开始题目
--1、查询“111”课程比“112”课程成绩高的所有学生的学号；
/* EXISTS 版本 */
SELECT t1.s#
FROM sc t1
WHERE t1.c# = 111
AND EXISTS (
SELECT 1
FROM sc t2
WHERE t2.c# = 112
AND t1.s# = t2.s# --要求同一个学生 所以有t1.s# = t2.s#
AND t1.score > t2.score
);
/* 子查询版本 */
SELECT a.s#
FROM (SELECT t1.s#,t1.score FROM sc t1 WHERE t1.c# = 111) a
INNER JOIN (SELECT t2.s#,t2.score FROM sc t2 WHERE t2.c# = 112) b
ON a.s# = b.s#
WHERE a.score > b.score; --2、查询平均成绩大于60分的同学的学号和平均成绩；
SELECT t1.s# AS ST_CODE,
AVG(t1.score) AS CU_AVG
FROM sc t1
GROUP BY t1.s#
HAVING AVG(t1.score) > 60 --3、查询所有同学的学号、姓名、选课数、总成绩；
/* group by 的时候要注意选出来的字段是不是都是聚合函数或者分组的字段 */
SELECT t1.s# AS ST_DOCE,
MIN(t1.sname) AS ST_NAME,
COUNT(t2.c#) AS CU_NUM,
SUM(t2.score) AS CU_SUM
FROM STUDENT t1
LEFT JOIN SC t2
ON t1.s# = t2.s#
GROUP BY t1.s# --4、查询姓“李”的老师的个数；
SELECT COUNT(t1.t#) AS 李_NUM
FROM teacher t1
WHERE t1.tname LIKE '李%' --5、查询没学过'陈奕迅'老师课的同学的学号、姓名；
/* 一对多关系的就会出现比较坑爹的情况，记得用distinct并且要考虑是不是要做一个子查询 */
/* 当正面来可能比较困难的时候就要反方面来进行 */
/* EXISTS版 */
SELECT t5.s# AS ST_CODE,
t5.sname AS ST_NAME
FROM student t5
WHERE NOT EXISTS (
SELECT 1
FROM (
SELECT DISTINCT t1.s# AS ST_CODE,
t1.sname AS ST_NAME,
t4.tname
FROM student t1
LEFT JOIN sc t2
ON t1.s# = t1.s#
LEFT JOIN course t3
ON t2.c# = t3.c#
LEFT JOIN teacher t4
ON t3.t# = t4.t#
WHERE t4.tname = '陈奕迅'
)
WHERE s# = t5.s#
);
/* 子查询版 */
SELECT t5.s# AS ST_CODE,
t5.sname AS ST_NAME
FROM student t5
WHERE t5. EXISTS (
SELECT 1
FROM (
SELECT DISTINCT t1.s# AS ST_CODE,
t1.sname AS ST_NAME,
t4.tname
FROM student t1
LEFT JOIN sc t2
ON t1.s# = t1.s#
LEFT JOIN course t3
ON t2.c# = t3.c#
LEFT JOIN teacher t4
ON t3.t# = t4.t#
WHERE t4.tname = '陈奕迅'
)
WHERE s# = t5.s#
); --6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
--不能在where条件下面写WHERE t2.c# = 111 and t2.c# = 112 因为是对应同一条记录的
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
LEFT JOIN sc t2
ON t1.s# = t2.s#
WHERE t2.c# = 111 INTERSECT --集合的交集 SELECT DISTINCT t1.s#,t1.sname
FROM student t1
LEFT JOIN sc t2
ON t1.s# = t2.s#
WHERE t2.c# = 112 --7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
SELECT DISTINCT t1.s# AS ST_CODE,
t1.sname AS ST_NAME,
FROM student t1
LEFT JOIN sc t2
ON t1.s# = t1.s#
LEFT JOIN course t3
ON t2.c# = t3.c#
LEFT JOIN teacher t4
ON t3.t# = t4.t#
WHERE t4.tname = '李冰冰' --8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；
/* 用单纯的join版 */
/* 用了子查询 */
SELECT a.s#
FROM (SELECT t1.s#,t1.score FROM sc t1 WHERE t1.c# = 111) a
INNER JOIN (SELECT t2.s#,t2.score FROM sc t2 WHERE t2.c# = 112) b
ON a.s# = b.s#
WHERE a.score < b.score --9、查询所有课程成绩小于60分的同学的学号、姓名；
SELECT T1.S#, T1.SNAME
FROM STUDENT T1
INNER JOIN SC T2
ON T1.S# = T2.S#
WHERE T2.C# < 60 --10、查询没有学全所有课的同学的学号、姓名；
/*子查询版*/
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
INNER JOIN SC t2
ON t1.s# = t2.s#
WHERE t2.c# IN (
SELECT t3.c#
FROM Course t3
)
/*exists版*/
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
INNER JOIN SC t2
ON t1.s# = t2.s#
WHERE EXISTS (
SELECT 1
FROM Course t3
WHERE t3.c# = t2.c#
) --11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；
/* 子查询 */
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
WHERE t2.c# IN (
SELECT t4.c#
FROM student t3
INNER JOIN sc t4
ON t3.s# = t4.s#
WHERE t3.s# = 1
)
/* exists版 */
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
WHERE EXISTS (
SELECT 1
FROM student t3
INNER JOIN sc t4
ON t3.s# = t4.s#
WHERE t4.c# = t2.c#
AND t3.s# = 1
) --12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名；
/* 子查询 */
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
AND t1.s# <> 1
WHERE t2.c# IN (
SELECT t4.c#
FROM student t3
INNER JOIN sc t4
ON t3.s# = t4.s#
WHERE t3.s# = 1
)
/* exists版 */
SELECT DISTINCT t1.s#,t1.sname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
AND t1.s# <> 1
WHERE EXISTS (
SELECT 1
FROM student t3
INNER JOIN sc t4
ON t3.s# = t4.s#
WHERE t4.c# = t2.c#
AND t3.s# = 1
) --13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；
UPDATE sc t4
SET t4.score = (
WITH tmp AS
(
SELECT t1.c#,
AVG(t1.score) AS avg_score
FROM sc t1
INNER JOIN Course t2
ON t1.c# = t2.c#
INNER JOIN teacher t3
ON t2.t# = t3.t#
GROUP BY t1.c#
)
SELECT t5.avg_score
FROM tmp t5
WHERE t4.c# = t5.c#
)
WHERE EXISTS (
SELECT 1
FROM sc t6
INNER JOIN Course t7
ON t6.c# = t7.c#
INNER JOIN teacher t8
ON t7.t# = t8.t#
AND t8.tname = '陈奕迅'
) 14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；
SELECT DISTINCT t1.s#,
t1.sname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
AND t2.c# = ALL (
SELECT t4.c#
FROM student t3
INNER JOIN sc t4
ON t3.s# = t4.s#
AND t4.s# = 7
)
AND t1.s# <> 7 --15、删除学习'陈奕迅'老师课的SC表记录；
DELETE FROM sc t1
WHERE EXISTS (
SELECT 1
FROM teacher t2
INNER JOIN Course t3
ON t2.t# = t3.t#
WHERE t3.c# = t1.c#
AND t2.tname = '陈奕迅'
) 16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、2号课的平均成绩；
INSERT INTO sc(s#,c#,score) SELECT min(t5.s#),112,AVG(t4.score)
FROM sc t4
INNER JOIN student t5
ON t4.s# = t5.s#
WHERE t4.s# NOT IN (
SELECT t2.s#
FROM student t2
INNER JOIN sc t3
ON t2.s# = t3.s#
AND t3.c# = 113
)
AND t4.c# = 112
GROUP BY t4.c# --17、按平均成绩从高到低显示所有学生的“语文1”、“生物2”、“化学1”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
/* 行转列除了可以用poivt外还可以分别select出来，再和主表的字段关联 */
SELECT t1.S# as 学生ID,
(SELECT score FROM SC t2 WHERE t2.S#=t1.S# AND t2.C#=111) AS 语文1,
(SELECT score FROM SC t3 WHERE t3.S#=t1.S# AND t3.C#=118) AS 生物2,
(SELECT score FROM SC t4 WHERE t4.S#=t1.S# AND t4.C#=121) AS 化学1,
COUNT(*) AS 有效课程数,
AVG(t1.score) AS 平均成绩
FROM SC t1
GROUP BY t1.S#
ORDER BY avg(t1.score) --18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
SELECT t1.c#,
MIN(t1.score) AS min_score,
MAX(t1.score) AS max_score
FROM sc t1
GROUP BY t1.c# --19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
SELECT t1.c#,
AVG(t1.score) AS avg_score,
100 * SUM(
CASE
WHEN nvl(t1.score,0)>=60 THEN
1
ELSE
0
END
)/COUNT(*) AS pass_pct
FROM sc t1
GROUP BY t1.c#
ORDER BY avg_score ASC,pass_pct DESC --20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 语文1（111），语文2（112），数学1（113），数学2（114）
SELECT SUM(CASE WHEN t1.c# =111 THEN score ELSE 0 END)/SUM(CASE t1.c# WHEN 111 THEN 1 ELSE 0 END) AS 语文1 ,
100 * SUM(CASE WHEN t1.c# = 111 AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN t1.c# = 111 THEN 1 ELSE 0 END) AS 语文1及格百分比 ,
SUM(CASE WHEN t1.c# = 112 THEN score ELSE 0 END)/SUM(CASE t1.c# WHEN 112 THEN 1 ELSE 0 END) AS 语文2 ,
100 * SUM(CASE WHEN t1.c# = 112 AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN t1.c# = 112 THEN 1 ELSE 0 END) AS 语文2及格百分比 ,
SUM(CASE WHEN t1.c# = 113 THEN score ELSE 0 END)/SUM(CASE t1.c# WHEN 113 THEN 1 ELSE 0 END) AS 数学1 ,
100 * SUM(CASE WHEN t1.c# = 113 AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN t1.c# = 113 THEN 1 ELSE 0 END) AS 数学1及格百分比 ,
SUM(CASE WHEN t1.c# = 114 THEN score ELSE 0 END)/SUM(CASE t1.c# WHEN 114 THEN 1 ELSE 0 END) AS 数学2 ,
100 * SUM(CASE WHEN t1.c# = 114 AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN t1.c# = 114 THEN 1 ELSE 0 END) AS 数学2及格百分比
FROM SC t1 --21、查询不同老师所教不同课程平均分从高到低显示
SELECT t3.tname,
t2.cname,
AVG(t1.score) AS avg_score
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
INNER JOIN teacher t3
ON t2.t# = t3.t#
GROUP BY t3.tname,t2.cname
ORDER BY avg_score DESC --22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（111），马克思（112），UML （113），数据库（114）
SELECT sub_query.cname,
sub_query.rank
FROM(
SELECT t2.cname,
t1.score,
rank() over(PARTITION BY t1.c# ORDER BY t1.score DESC) AS rank
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
WHERE t1.c# IN (111,112,113,114)
) sub_query
WHERE sub_query.rank BETWEEN 3 AND 6; --23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85] 优秀人数,[85-70] 良好人数,[70-60] 一般人数,[ <60] 刚及格人数
SELECT t1.c#,
t2.cname,
SUM(CASE WHEN t1.score > 85 AND t1.score <= 100 THEN 1 ELSE 0 END) AS 优秀人数,
SUM(CASE WHEN t1.score > 70 AND t1.score <= 85 THEN 1 ELSE 0 END) AS 良好人数,
SUM(CASE WHEN t1.score > 60 AND t1.score <= 70 THEN 1 ELSE 0 END) AS 一般人数,
SUM(CASE WHEN t1.score <= 60 THEN 1 ELSE 0 END) AS 刚及格人数
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
GROUP BY t1.c#,t2.cname --24、查询学生平均成绩及其名次
SELECT t1.sname,
t1.s#,
AVG(t2.score) AS avg_score,
dense_rank() over(ORDER BY AVG(t2.score) DESC) AS dense_rank
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
GROUP BY t1.sname,t1.s# --25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT sub_query.cname,
sub_query.s#,
sub_query.sname,
sub_query.score,
sub_query.rank
FROM (
SELECT t3.cname,
t1.s#,
t1.sname,
t2.score,
rank() over(PARTITION BY t2.c# ORDER BY t2.score DESC) AS rank
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
INNER JOIN course t3
ON t2.c# = t3.c#
) sub_query
WHERE sub_query.rank < 4 --26、查询每门课程被选修的学生数
SELECT t2.cname,
COUNT(t1.s#) AS sum_stu
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
GROUP BY t2.cname --27、查询出只选修了一门课程的全部学生的学号和姓名
/* GROUP BY 语句中选择出来的只有备份组的字段和聚合函数 */
SELECT t1.s#,
t1.sname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
GROUP BY t1.s#,t1.sname
HAVING COUNT(t2.c#) = 1 --28、查询男生、女生人数
SELECT t1.ssex,
COUNT(t1.ssex) AS sex_num
FROM student t1
GROUP BY t1.ssex --29、查询名字中有'黑'的学生名单
SELECT t1.s#,
t1.sname
FROM student t1
WHERE t1.sname LIKE '%黑%' --30、查询同名同性学生名单，并统计同名人数
/* 写了个错的
原因：student表中有两个小粉，on条件只是县限定了sname相等，所以导致了2X2的笛卡尔乘积*/
SELECT t1.sname,
COUNT(t1.s#) AS same_name_count
FROM student t1
INNER JOIN student t2
ON t1.sname = t2.sname
GROUP BY t1.sname,t2.sname
HAVING COUNT(t1.sname) > 1
/* 正确的写法 */
SELECT t1.sname,
COUNT(t1.sname) AS same_name_count
FROM student t1
GROUP BY t1.sname
HAVING COUNT(t1.sname) > 1 --32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
SELECT t2.cname,
t2.c#,
AVG(t1.score) AS avg_score
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
GROUP BY t2.cname,t2.c#
ORDER BY avg_score ASC,t2.c# DESC --33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
SELECT t1.s#,
t1.sname,
AVG(t2.score) AS avg_score
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
GROUP BY t1.s#,t1.sname
HAVING AVG(t2.score) > 85 --34、查询课程名称为'语文1'，且分数低于60的学生姓名和分数
SELECT t1.sname,
t2.score
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
INNER JOIN course t3
ON t2.c# = t3.c#
WHERE t3.cname = '语文1'
AND t2.score < 60 --35、查询所有学生的选课情况；
/* 可能不是这样写，有更好的写法 */
SELECT t1.s#,
t1.sname,
t3.cname
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
INNER JOIN course t3
ON t2.c# = t3.c# --36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
SELECT t1.s#,
t1.sname,
t3.cname,
t2.score
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
INNER JOIN course t3
ON t2.c# = t3.c#
WHERE t2.score > 70 --37、查询不及格的课程，并按课程号从大到小排列
SELECT t1.c#,
t2.cname,
t1.score
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
WHERE t1.score < 60
ORDER BY t1.c# DESC --38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
SELECT t1.s#,
t1.sname,
t2.score
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
INNER JOIN course t3
ON t2.c# = t3.c#
WHERE t2.c# = 113
AND t2.score > 80 --39、求选了课程的学生人数
SELECT SUM(1)
FROM (
SELECT 1
FROM sc t1
GROUP BY t1.s#
) --40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
SELECT t4.s#,
t4.sname,
t5.score,
t6.cname
FROM student t4
INNER JOIN sc t5
ON t4.s# = t5.s#
INNER JOIN course t6
ON t5.c# = t6.c#
WHERE (t5.score,t6.cname) IN (
SELECT MAX(t1.score),
t2.cname
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
INNER JOIN teacher t3
ON t2.t# = t3.t#
WHERE t3.tname = '陈奕迅'
GROUP BY t2.cname
) --41、查询各个课程及相应的选修人数
SELECT t1.c#,
t2.cname,
COUNT(t1.s#)
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
GROUP BY t1.c#,t2.cname --42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
SELECT t1.s#,
t1.c#,
t1.score
FROM sc t1
INNER JOIN sc t2
ON t1.score = t2.score
AND t1.c# <> t2.c#
AND t1.s# = t2.s# --43、查询每门功成绩最好的前两名
SELECT sub_query.s#,
sub_query.sname,
sub_query.cname,
sub_query.score,
sub_query.rank
FROM (
SELECT t1.s#,
t3.sname,
t2.cname,
t1.score,
dense_rank() over(PARTITION BY t1.c# ORDER BY t1.score DESC) AS rank
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
INNER JOIN student t3
ON t1.s# = t3.s#
) sub_query
WHERE sub_query.rank < 3 --44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列
SELECT t1.c#,
COUNT(t1.s#) AS stu_num
FROM sc t1
GROUP BY t1.c#
HAVING COUNT(t1.s#) > 10
ORDER BY stu_num DESC,t1.c# ASC --45、检索至少选修两门课程的学生学号
SELECT t1.s#
FROM sc t1
GROUP BY t1.s#
HAVING COUNT(t1.c#) > 1 --46、查询全部学生都选修的课程的课程号和课程名
SELECT t1.c#,
t2.cname,
COUNT(t1.s#)
FROM sc t1
INNER JOIN course t2
ON t1.c# = t2.c#
GROUP BY t1.c#,t2.cname
HAVING COUNT(t1.s#) = (
SELECT COUNT(t3.s#)
FROM student t3
) --47、查询没学过'陈奕迅'老师讲授的任一门课程的学生姓名
SELECT t5.s#,
t5.sname
FROM student t5
WHERE t5.s# NOT IN (
SELECT DISTINCT t1.s#
FROM student t1
INNER JOIN sc t2
ON t1.s# = t2.s#
INNER JOIN course t3
ON t2.c# = t3.c#
INNER JOIN teacher t4
ON t3.t# = t4.t#
WHERE t4.tname = '陈奕迅'
) --48、查询两门以上不及格课程的同学的学号及其平均成绩
/* 不能直接用下面的方式，因为有where条件过滤了一部分的成绩
SELECT t1.s#,
AVG(t1.score)
FROM sc t1
WHERE t1.score < 60
GROUP BY t1.s#
HAVING COUNT(t1.c#) > 2 */
SELECT t2.s#,
AVG(t2.score)
FROM sc t2
WHERE t2.s# IN (
SELECT t1.s#
FROM sc t1
WHERE t1.score < 60
GROUP BY t1.s#
HAVING COUNT(t1.c#) > 2
)
GROUP BY t2.s# --49、检索'114'课程分数小于60，按分数降序排列的同学学号
SELECT t1.s#
FROM sc t1
WHERE t1.c# = 114
AND t1.score < 60
ORDER BY t1.s# DESC --50、删除'2'同学的'111'课程的成绩
DELETE FROM sc t1
WHERE t1.s# = 2
AND t1.c# = 111
面试题 数据库sql的更多相关文章
- php开发面试题---数据库SQL调优的几种方式
php开发面试题---数据库SQL调优的几种方式 一.总结 一句话总结: 创建索引:尽量避免使用or或者like,或者sql中的正则 存储查询中间结果 可以加sphinx搜索技术 查询优化 主从数据库 ...
- 面试题: 数据库 sql优化 sql练习题 有用 学生表,课程表,成绩表,教师表 练习
什么是存储过程?有哪些优缺点? 什么是存储过程?有哪些优缺点? 存储过程就像我们编程语言中的函数一样,封装了我们的代码(PLSQL.T-SQL). 存储过程的优点: 能够将代码封装起来 保存在数据库之 ...
- 数据库MySQL经典面试题之SQL语句
数据库MySQL经典面试题之SQL语句 1.需要数据库表1.学生表Student(SID,Sname,Sage,Ssex) --SID 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学 ...
- 部分常见ORACLE面试题以及SQL注意事项
部分常见ORACLE面试题以及SQL注意事项 一.表的创建: 一个通过单列外键联系起父表和子表的简单例子如下: CREATE TABLE parent(id INT NOT NULL, PRIMARY ...
- 关于数据库SQL优化
1.数据库访问优化 要正确的优化SQL,我们需要快速定位能性的瓶颈点,也就是说快速找到我们SQL主要的开销在哪里?而大多数情况性能最慢的设备会是瓶颈点,如下载时网络速度可能会是瓶颈点,本地复制文件 ...
- Oracle 数据库SQL性能查看
作为一个开发/测试人员,或多或少都得和数据库打交道,而对数据库的操作归根到底都是SQL语句,所有操作到最后都是操作数据,那么对sql性能的掌控又成了我们工作中一件非常重要的工作.下面简单介绍下一些查看 ...
- 你用什么方法检查 PHP 脚本的执行效率（通常是脚本执行时间）和数据库 SQL 的效率（通常是数据库 Query 时间）， 并定位和分析脚本执行和数据库查询的瓶颈所在？
php: 一般是在你要检查的代码开头记录一个时间,结尾记录一个时间.取差值, 数据库SQL的效率 sql的explain(mysql),启用slow query log记录慢查询. 通常还要 ...
- 数据库SQL Server与C#中数据类型的对应关系
ylbtech- .NET-Basic:数据库SQL Server与C#中数据类型的对应关系 数据库SQL SServer与C#中数据类型的对应关系 1.A,返回顶部 数据库 C#程序 int int ...
- 我的mysql数据库sql优化原则
原文 我的mysql数据库sql优化原则 一.前提 这里的原则 只是针对mysql数据库,其他的数据库 某些是殊途同归,某些还是存在差异.我总结的也是mysql普遍的规则,对于某些特殊情况得特殊对待. ...
随机推荐
- mysql 字符串的截取与连接
mysql 字符串的截取 left() .right() . substring()[ mid() .substr() 等价于substring() ] .substring_index() l ...
- [转]解读Unity中的CG编写Shader系列二
上一篇文章的例子中我们可以看到顶点着色器的输出参数可以说是直接作为了片段着色器的形参传递过来,那么不由得一个问题浮现出来,顶点着色器的形参是从何处传递过来的? 顶点着色器的形参是gameObject ...
- dubbo服务治理中间件,zookeeper注册中心 安装配置
对传统项目架构进行拆分: 集群概念: 面向服务分布式架构: 服务层提供被注册的对象需要实现序列化接口Serializable: 配置表现层和服务层: 依赖包: 服务层: <!-- 定义dubbo ...
- sklearn的train_test_split函数
train_test_split函数用于将矩阵随机划分为训练子集和测试子集,并返回划分好的训练集测试集样本和训练集测试集标签. from sklearn.model_selection import ...
- 【bzoj1014】: [JSOI2008]火星人prefix 平衡树-字符串-hash-二分
[bzoj1014]: [JSOI2008]火星人 用平衡树维护字符串的hash 然后询问的时候二分一下就好了 /* http://www.cnblogs.com/karl07/ */ #includ ...
- requests库和urllib包对比
python中有多种库可以用来处理http请求,比如python的原生库:urllib包.requests类库.urllib和urllib2是相互独立的模块,python3.0以上把urllib和ur ...
- Python之路系列：面向对象初级：静态属性、静态方法、类方法
一.静态属性 静态属性相当于数据属性. 用@property语法糖装饰器将类的函数属性变成可以不用加括号直接的类似数据属性. 可以封装逻辑,让用户感觉是在调用一个普通的数据属性. 例子: class ...
- 我的csdn博客地址
呆雁 持续的谦虚与努力 http://blog.csdn.net/u013539183
- CentOS安装pip并修改源为豆瓣源
使用yum进行安装 yum install python-pip 若出现 No package python-pip available. 则解决方法如下: yum -y install epel-r ...
- STM32基础分析——PWM配置
在使用STM32F103产生固定频率.固定占空比的PWM波时,虽然有官方以及众多开发板提供的例程,但是关于有点问题并没有说的很清晰,并且<STM32F10X参考手册>的中文翻译可能容易造成 ...