• Unless you have a very specific reason to use a NULL value, you should always set your columns as NOT NULL.

    除非一个特别原因使用NULL应该总是字段保持NOTNULL。 这看起来好像有点争议,请往下看。

    yq329.blog.163.com

  • An error could occur in the first test and prevent the variable's value from being set, thus resulting in the other tests receiving a null value.

    错误可以发生首个测试期间,阻止您去设置变量导致其他测试接受一个

    www.ibm.com

  • This new validation will enforce NOT NULL column constraints by rejecting null values, but only in situations where your database would reject a null value.

    这种校验通过拒绝强迫加上[NOTNULL]字段约束但是也只有这种情况数据库拒绝

    www.infoq.com

  • If the former is true, then the indicator variable for that column is set to -1 which results in the column being updated with the null value.

    如果一种情况那么指示符变量设置-1导致更新

    www.ibm.com

  • Moreover, when value compression is used, the system consumes one byte less for each table entry for all columns in which a NULL value is allowed.

    而且如果使用压缩对于允许NULL所有其中每个条目可以一个字节

    www.ibm.com

  • That is the retrieved NULL value for a named column is ignored and not used to update the out going message assembly for the element concerned.

    忽略针对指定元素检索得到NULL并且使用更新相关元素输出消息组件

    www.ibm.com

  • If no match is found within the input, a null value is returned.

    如果输入找到匹配项返回

    blog.sina.com.cn

  • This gave rise to the need for a "null value" to represent unknown or inapplicable values in relational databases.

    产生对于“空值(null value)”的需要用以关系数据库表示未知不适用

    www.ibm.com

  • Otherwise, the shell interprets the trailing text as part of your variable name -- and most likely returns a null value.

    否则Shell尾随文本解释变量名称一部分——并且可能返回一个

    www.ibm.com

  • Without this requirement, the itemNumber column isn't guaranteed to be unique because multiple columns could be assigned a NULL value.

    如果没有这个要求itemNumber无法保持惟一因为多个行都可能分配NULL

    www.ibm.com

  • If there is only one non-NULL value in the column

    如果只有一个

    www.ibm.com

  • The description column is left empty, which means it will have a NULL value.

    description为空白意味着具有NULL

    www.ibm.com

  • Some JSF components, such as <h:selectOneMenu> do recognize the missing data in the request map value as a null value and try to pass the validation process with a failed result.

    有些JSF组件例如 <h:selectOneMenu>,会重新识别请求映射作为null丢失数据尝试通过验证过程得到失败结果

    www.ibm.com

  • A general, good practice is not to allow null (that is, no value) columns in a relational database, because when you attempt to read such a column, you get a null value exception.

    通常一种优秀实践就是不要关系数据库中使用null(即没有因为试图读取这类将得到一个null异常

    www.ibm.com

  • As you saw in Section 1, DB2 implicitly allocates memory for arrays when they are initialized with a non-NULL value or when they grow past their current size.

    正如1部分所看到的,通过NULL初始化阵列时或阵列增长超过它们当前小时,DB2隐式阵列分配内存

    www.ibm.com

  • If nullable, it will contain the NULL value.

    如果可为空包含NULL

    www.ibm.com

  • By default, a column can contain a NULL value, but if you don't want that, you can append the "NOT NULL" postfix to the field definition.

    默认情况下可以包含NULL但是如果不想这样,可以字段定义附加NOTNULL后缀

    www.ibm.com

  • In addition, if you have a table with many columns that aren't typically used, you are also wasting disk space with NULL value fields.

    此外如果常用多个的一个通过NULL字段浪费磁盘空间

    www.ibm.com

  • In a relational database, you end up with many records with a null value in the fax column (for instance) for every one or two that utilizes that value.

    关系数据库中,一个两个利用传真,通过例如完成许多记录

    www.ibm.com

  • That means a reference type can have a null pointer, but a value type cannot have a null value.

    意味着引用类型可能有空指针但是数值类型不能有空

    www.ibm.com

  • This may be in the form of specific set values (for example, all 9’s orDo Not Use’) or blank values (where a blank represents a keystroke distinct from a null value).

    可能特定设置例如所有9DoNotUse’)空白一个空白表示一个按键,这不同一个null)的形式出现。

    www.ibm.com

  • On Linux and UNIX platforms, a NULL value defaults to the primary group of the instance owner, which by default after an installation only contains the user ID of the instance owner.

    LinuxUNIX平台上NULL缺省实例所有者完成安装缺省情况下这个包含用户ID实例所有者

    www.ibm.com

  • If this column is not sorted, a null value is returned, and the @formulas in the agent will not continue executing.

    如果进行排序返回代理中的 @formulas不再继续执行

    www.ibm.com

  • Click on CustomerRecord(), and you will see a non-null value appear as the value in the parameters area.

    单击CustomerRecord(),看到出现一个作为参数区域中的

    www.ibm.com

  • This is a good start, but you need to provide something other than a null value when the Tree Viewer asks for the column text for a particular item.

    一个很好的开始但是为了一个特殊条目TreeViewer需要栏目文本需要提供一些内容,而不仅仅是一个

    www.ibm.com

  • But, in DB2 z/OS if a UNIQUE index is created on a column, then only one NULL value can be inserted into it.

    但是DB2z/OS 中,如果创建UNIQUE索引那么只能其中插入一个NULL

    www.ibm.com

  • Otherwise, an attempt to insert a record with a NULL value for the partitioning key will result in a "data out of bounds" error.

    否则插入分区列为 NULL记录时,产生dataoutofbounds错误

    www.ibm.com

  • Now, even if the same code segment tries to access p before a value has been assigned to it and it has proper handling of the Null value (which ideally it should be), then it will behave properly.

    现在即使同一个代码尝试p访问,该代码也能正确处理Null在理想情况下具有的),然后具有正确行为

    www.ibm.com

  • What if someone inadvertently passes in a null value for the Class parameter?

    如果有人不经意Class参数传入一个null会怎么样呢?

    www.ibm.com

  • First, the actual occurrence of a specific value may indicate whether there are issues such as incomplete data by the presence of a Null value, a Space, and so on.

    首先一个特定实际出现可能表明是否存在问题例如由于Null空格造成的不完整

    www.ibm.com

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