nulls

简明释义

英[nʌlz]美[nʌlz]

n. 无意义暗码；[电子]零位（null 的复数）

v. 使无效；取消（null 的单三形式）

英英释义

单词用法

同义词

反义词

例句

1.For each of the columns, be sure to select the right data type and to uncheck the Allow Nulls options.

对每个列，要确保选择了正确的数据类型，并取消“允许为空”复选框。

2.Since the requirement is to only suppress nulls, the visual null suppression can be replaced by the null suppression on the actual query.

因为需求是仅抑制nulls，可视的nullsuppression可由实际查询上的null suppression替换。

3.The additional column can have a (false) default value that is modified only when the partner column has a value, avoiding the need for nulls.

这个额外的列可以拥有一个(假)默认值，这个值仅在partner列有值时才被修改，从而避免使用null值。

4.Likewise, if the NULLS last option is used, the last partition must end with MAXVALUE.

同样，如果使用NULLS LAST选项，最后一个分区必须结束于MAXVALUE。

5.SQL USES a small integer which contains a zero if the column is not null or -1 if the column contains nulls.

如果列不包含空值，则SQL使用一个包含一个0的小整数；反之则包含- 1。

6.Nulls are not matched to any value, including other instances of null.

空值不与任何值匹配，包括其他实例的空值。

7.The general requirement for these algorithms is that the container does not contain any nulls.

这些算法的通用要求是，容器不能包含任意空值。

8.It's the situation where, for instance, someone passes a null value to a method not coded to handle nulls.

比方说，把null值传入一个并未编写如何处理null值的方法中，这就是一种边界情况。

9.In the database, some fields contain nulls (空值) which need to be addressed in the query.

在数据库中，一些字段包含nulls（空值），需要在查询中处理。

10.When calculating averages, we must ignore the nulls (空值) to avoid skewed results.

在计算平均值时，我们必须忽略nulls（空值），以避免结果失真。

11.The API returned a list with several nulls (空值), indicating missing data.

API返回的列表中有几个nulls（空值），表示缺失数据。

12.To clean the dataset, we need to remove all nulls (空值) from the columns.

为了清理数据集，我们需要从列中删除所有nulls（空值）。

13.Some programming languages treat nulls (空值) as equivalent to zero, which can lead to confusion.

一些编程语言将nulls（空值）视为零，这可能导致混淆。

作文

In the realm of computer programming and data management, the term nulls refers to the absence of a value or a non-existent entry in a database. Understanding how nulls function is crucial for developers and data analysts alike, as they can significantly impact the results of queries and data manipulation. This essay will explore the concept of nulls, their implications in programming, and how they can be effectively managed to ensure data integrity. To begin with, nulls are commonly encountered in relational databases. They signify that a particular field does not have any value assigned to it. For example, consider a database that stores information about students. If a student has not provided their middle name, the corresponding field in the database would contain a null value. This indicates that the information is either unknown or not applicable. The presence of nulls can help differentiate between a legitimate value (like an empty string) and a complete absence of data. However, nulls can also complicate data analysis and processing. When performing calculations or comparisons, nulls can lead to unexpected results. For instance, if we try to calculate the average age of students in our database and some entries contain nulls, these entries must be handled appropriately to avoid skewing the results. Many programming languages and database systems provide functions to deal with nulls, such as ignoring them in calculations or replacing them with default values. Moreover, the handling of nulls varies across different programming languages. In SQL, nulls are treated distinctly from other values. For instance, when comparing values, any comparison involving a null will yield a null result. This behavior can lead to confusion if one is not aware of how nulls operate within the language. Therefore, it is essential for programmers to understand the specific rules governing nulls in the language they are using to avoid logical errors in their code. In addition to their technical implications, nulls also raise philosophical questions about data completeness and accuracy. In many cases, the presence of nulls can indicate a lack of information that may be critical for decision-making processes. Organizations must decide how to handle nulls based on their specific needs and objectives. Some may choose to ignore nulls entirely, while others may implement strategies to collect the missing data or to provide default values that can serve in place of nulls. Furthermore, data integrity is a vital consideration when dealing with nulls. It is important to establish clear guidelines on when to use nulls and when to provide actual values. This ensures that the data remains consistent and reliable. For instance, in a customer relationship management system, if a customer's phone number is unknown, it may be more appropriate to store a null rather than an incorrect placeholder like 'N/A'. This clarity helps maintain the quality of the data and supports better analytics. In conclusion, the concept of nulls plays a significant role in the world of data management and programming. Their presence indicates missing information, which can lead to challenges in data analysis and processing. By understanding how nulls work and implementing effective strategies to manage them, developers and analysts can ensure data integrity and make more informed decisions. As technology continues to evolve, the ability to handle nulls proficiently will remain an essential skill in the toolkit of any data professional.

在计算机编程和数据管理的领域中，术语nulls指的是数据库中缺少值或不存在条目的情况。理解nulls的功能对于开发人员和数据分析师来说至关重要，因为它们会显著影响查询和数据操作的结果。本文将探讨nulls的概念、它们在编程中的影响，以及如何有效管理它们以确保数据完整性。 首先，nulls通常出现在关系数据库中。它们表示特定字段没有分配任何值。例如，考虑一个存储学生信息的数据库。如果一名学生没有提供中间名，则该数据库中的相应字段将包含null值。这表明该信息要么未知，要么不适用。nulls的存在有助于区分合法值（例如空字符串）和数据的完全缺失。 然而，nulls也可能使数据分析和处理变得复杂。在进行计算或比较时，nulls可能导致意想不到的结果。例如，如果我们尝试计算数据库中学生的平均年龄，而某些条目包含nulls，则必须妥善处理这些条目，以避免扭曲结果。许多编程语言和数据库系统提供了处理nulls的函数，例如在计算中忽略它们或用默认值替换它们。 此外，处理nulls的方法因不同的编程语言而异。在SQL中，nulls与其他值的处理是截然不同的。例如，当比较值时，任何涉及null的比较都将产生null结果。如果一个人不知道nulls在语言中的运作方式，这种行为可能会导致困惑。因此，程序员必须理解他们所使用的语言中关于nulls的具体规则，以避免代码中的逻辑错误。 除了技术影响外，nulls还引发了关于数据完整性和准确性的哲学问题。在许多情况下，nulls的存在可能表明缺乏关键信息，这对决策过程至关重要。组织必须根据其特定需求和目标决定如何处理nulls。一些组织可能选择完全忽略nulls，而另一些组织可能实施收集缺失数据或提供可以替代nulls的默认值的策略。 此外，在处理nulls时，数据完整性是一个重要的考虑因素。建立清晰的指导方针，以确定何时使用nulls以及何时提供实际值至关重要。这确保了数据的一致性和可靠性。例如，在客户关系管理系统中，如果客户的电话号码未知，存储一个null可能比一个不正确的占位符（如'N/A'）更合适。这种清晰度有助于维护数据的质量，并支持更好的分析。 总之，nulls的概念在数据管理和编程的世界中发挥着重要作用。它们的存在表示缺失的信息，这可能导致数据分析和处理中的挑战。通过理解nulls的工作原理并实施有效的管理策略，开发人员和分析师可以确保数据完整性并做出更明智的决策。随着技术的不断发展，熟练处理nulls的能力将始终是任何数据专业人员工具箱中的一项基本技能。