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The economics of cheating

As a college student, I worked 15 hours a week at the university

reseach institute. The job was fun, but I worked out of necessity.

School was expensive, and the extra income was a must. One day a

week, I put notices on the mailboxes of dozens of professors. One

afternoon as I was stuffing the mailbox as the economics

department, I noticed a large stack of papers in the mailbox as one

of my instructors. The top sheet read, “ answer key, econ.303

problem set. ” economics 303, econ.303, was my toughest class that

he mastered. It covered the tick and introductory econometrics. The

problem sets were very time consuming. Looking at the stack, I

thought how easily I could take a copy of the top. No one would see

me. I was totally alone. In the end, I didn’t take a copy. Instead, I

stay up late that night finishing the problem set. In class the next day,

I handed the assignment in and received the same answer sheet I

had seen the day before. With a deep sight, I reviewed my mistakes.

Resisting temptation became a weekly ritual. The papers called to

me every week. There were so many copies of the answer key that I

knew no one will notice if I took one. As the assignments became

more difficult, it became more and more difficult to walk away. I

became thinking a reason for taking a copy. The detail answer sheet

would be a great learning tool, a study aid really. I wouldn’t stop doing the homework. I would simply look at the answers if I got

stuck. I saved time. It would even help the poor overworked

teaching assistant who had to figure out my errors. How selfless of

me. Thus the master grew more and tense. Classes, work at the

institute, singing her souls, my girlfriend, those were sufferable

problem sets. I became feeling overwhelmed by all these

commitments. I finally decided to take a answer key. I remembered

walking in the economics mail room, half hoping the papers wouldn’t

be there. But there they were as always, and as always, there was no

one around. All I had to do was take top copy and put it into my

bookbag. But I stood there, thinking about the consequences. Of

course there was the honor coat I sighted, but more disturbing to me

was the possibility I could be caught. Maybe the copies were

numbered. Perhaps the classmates would find out. Was it worth it?

Was saving myself a few hours of work worth the risks spent

generous explosion? Calculating the costs and benefits, I decided I

work too hard to throw everything away on something like this. The

benefits would be small and the possible downside enormous. I

walked away. Seven years later, my college deployment now sets up

a corner bookshop in my livingroom. It is one of the first things I see

when I walk in the door and the source of great pride. I wonder

would I look upon it differently if I had taken the answer key? Maybe I would. My achievement would be demolished. My pride qualified.

Perhaps, most important the sacrifices my family made so I could

attend the first tier university would be betrayed. But I can’t

congratulate myself too much, because my decision was based on

peer as well as princple. Does the motivation matter? Or does it still

crowd us doing the right thing when you do it for the wrong reasons?

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sql语法group contact

sql语法group contact

一、概述

SQL是一种用于管理和操作关系型数据库的标准化语言，是几乎所有现代数据库系统的核心。在使用SQL语言时，一些高级功能经常会增加对其深入理解和灵活应用的需求。其中之一就是使用GROUP

CONTACT语法。在本文中，我们将详细介绍GROUP CONTACT语法的使用方法以及其在数据库管理中的重要性。

二、GROUP CONTACT语法概述

1. GROUP CONTACT的基本概念

GROUP CONTACT语法是SQL语言中用于将分组数据合并成一个字段的语法。它通常用于将分组数据按指定的分隔符合并成一个字段，便于统计和分析。在实际的数据库管理中，这项功能非常有用。

2. GROUP CONTACT的语法结构

GROUP CONTACT语法的基本结构如下：

```

SELECT column_name, GROUP_CONTACT(expr)

FROM table_name

[WHERE condition]

GROUP BY column_name; ```

其中，column_name指定了需要按照其进行分组的字段；GROUP_CONTACT(expr)中的expr指定了需要合并的字段或表达式；table_name指定了数据来源的表格；[WHERE condition]用于指定筛选条件，可选；GROUP BY column_name表示按照column_name进行分组。

3. GROUP CONTACT的应用场景

GROUP CONTACT语法的主要应用场景包括但不限于：合并相同分组的数据、统计分组数据、生成报表等。

三、GROUP CONTACT语法的使用示例

为了更好地理解GROUP CONTACT语法的使用方法，我们将结合一个简单的示例来演示其用法。假设我们有一个学生成绩表格，包括尊称、科目和成绩三个字段。我们想要统计每个学生的所有科目的成绩，并将其合并成一个字段，以便生成学生成绩单。

group by desc用法

group by desc用法

group by desc用法

Group by desc是一种在SQL语句中使用的命令，它的作用是按照指定字段对数据进行分组，并按照指定字段的降序排列。以下是Group

by desc的详细用法：

1. 语法格式

SELECT column_name1, column_name2, ... FROM table_name

GROUP BY column_name ORDER BY column_name DESC;

其中，column_name是需要进行分组和排序的字段名称，table_name是需要查询数据的表名称。

2. 使用示例

例如，我们有一个名为“students”的表，其中包含学生姓名（name）、年龄（age）和成绩（score）三个字段。现在我们需要按照成绩对学生进行分组，并按照成绩从高到低排序。

则可以使用以下SQL语句：

SELECT name, age, score FROM students GROUP BY score

ORDER BY score DESC;

执行该语句后，将会按照成绩对学生进行分组，并将每个分组中成绩最高的学生显示出来。同时，这些学生将按照成绩从高到低排序。

3. 注意事项

- 在使用Group by desc时，必须先指定要进行分组的字段名称，然后才能使用Order by对其进行排序。

- 如果想要在结果集中显示其他未被分组或排序的字段，则需要在Select子句中指定。

- Group by desc常与聚合函数（如Sum、Count等）一起使用，以实现更复杂的数据统计和汇总功能。

综上所述，Group by desc是一种非常实用的SQL命令，它可以帮助我们快速对数据进行分组和排序，并提供更加灵活的数据处理能力。

group_concat用法

group_concat用法

- 1 - group_concat用法

在使用MySQL数据库进行数据存储和检索时，group_concat函数可以在SELECT语句中使用，以查询出满足条件的行并将它们直接组合在一起。group_concat函数的主要目的是将多行的查询结果归并到一行中。本文将重点介绍group_concat函数的用法。

一、 group_concat函数的一般语法

group_concat函数的一般语法如下：

SELECT GROUP_CONCAT (DISTINCT column_name ORDER BY

col_name ASC/DESC separator separator_value ) FROM

table_name WHERE condition ;

其中，column_name表示要组合的列名；ORDER BY col_name

ASC/DESC表示结果的排序方式；separator_value表示组合后结果各个项目之间的分隔符；table_name表示要查询数据表；condition表示查询满足的条件。

二、group_concat函数的实例

group_concat函数可以用于各种场景，以下是一个实例说明：

假设有一个表：

course

name

math

language

现在要求将表中的name列的值按字母顺序按逗号分隔拼接起来， - 2 - 则可以使用group_concat函数：

SELECT GROUP_CONCAT(name ORDER BY name ASC SEPARATOR )

FROM course;

运行上述语句，结果为：language, math

三、group_concat函数的应用

1.多行查询结果拼接成字符串：

当我们需要将多行查询结果拼接成字符串时，可以考虑使用group_concat函数。例如，我们可以检索一张表中某人参加的课程，并将各种课程拼接起来：

groupmod-g用法

groupmod-g用法

groupmod-g用法

groupmod是一个针对Linux系统中的用户组进行管理的命令行实用程序。它提供了修改用户组属性和权限的功能，例如更改用户组名称、修改用户组ID和管理普通用户的归属等。本文将逐步回答关于groupmod命令的使用方法和注意事项。

第一步：了解groupmod的基本语法和选项

groupmod命令的基本语法如下：

bash

groupmod [options] GROUP

其中，GROUP是要修改的用户组名称。而options选项可根据需要来进行设置，下面是一些常见的选项：

- -g，gid GID：设置用户组的新ID。

- -n，new-name NEW_GROUP：设置用户组的新名称。

- -o，non-unique：允许使用非唯一的GID。

第二步：修改用户组名称

要修改用户组的名称，可以使用`-n`选项并指定新的名称。例如，要将用户组oldgroup更改为newgroup，可以执行以下命令：

bash

sudo groupmod -n newgroup oldgroup

第三步：更改用户组ID

使用`-g`选项可以更改用户组的ID。ID必须是唯一的，并且应该避免与其他现有用户组的ID冲突。例如，要将用户组group1的ID更改为1001，可以执行以下命令：

bash

sudo groupmod -g 1001 group1

第四步：使用非唯一的GID

默认情况下，每个用户组都有唯一的ID。但是，使用`-o`选项可以允许使用非唯一的GID。这可能会导致一些潜在的问题，因此应慎重使用该选项。例如，要将用户组group2的ID更改为非唯一，并将其设置为1010，可以执行以下命令：

bash

sudo groupmod -o -g 1010 group2

第五步：注意事项

在使用groupmod命令时，需要注意以下几点：

1. 只有root用户或具有sudo权限的用户才能执行groupmod命令。