RPG uses a 1 character field (like an indicator) to determine if a column contains nulls.
RPG使用一个1字符字段（比如一个指示符）来确定列是否包含空值。
That code would have created a new trail with a Trail object with nulls for all attributes.
这个代码应当创建一条新路线，该路线有一个所有属性都为null 的Trail对象。
For this report run only nulls are being suppressed on both the row and column edge of the crosstab.
对于该报表运行，仅在交叉表的行和列边缘上抑制了nulls。
SQL/XML is good if you want results returned as sets and missing XML elements represented with nulls.
如果您希望将结果作为集合返回，且将丢失的XML元素表示为空，那么SQL/XML有优势。
The two nulls indicate that we do not want to change the last access time or creation time for this file.
这两个null指出，我们不想改变这一文件的最后访问时间或者创建时间。
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。
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。
Define a primary key to enforce uniqueness for values entered in specified columns that do not allow nulls.
定义主键以对不允许空值的指定列中输入的值强制唯一性。
While a normal index can be used, it wastes a lot of space for nulls you are probably not going to query against.
如果使用普通索引的话，即使你并不打算对它进行查询，它也会因为null值浪费大量的空间。
In the bulk copy, all you need to do is select only those rows that have no nulls in the latitude and longitude columns.
在批量复制中，只选择在latitude和longitude列中没有null值的那些行。
Finally, if you lack email addresses for some Gold customers, you may want to write a query to exclude nulls from the result set.
最后，如果有些Gold客户没有email地址，那么可能要编写一个查询从结果集中排除null值。
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。
This paper deals with the semantics of null values in functional dependencies in database theory, and presents three different definitions of FDs in a single relation with marked nulls.
本文研究关系数据库理论中空值在函数依赖中的语义问题，提出了带标志空值的关系中函数依赖的三种定义。
The number of NULLs in the column.
列中null值的个数。
The CWF fields must be padded with SPACES (not NULLS).
CWF字段必须带空格(而不是NULL)。
The value for the first key is 4 bytes long and it is entirely NULLs.
第一个键的值为4字节且其完全为 NULL。
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。
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。
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。
It is important to note that when the NULLS first option is specified, the first partition must start at MINVALUE.
一定要注意，当指定NULLS FIRST选项时，第一个分区必须从MINVALUE开始。
To work around this problem, select the following columns of the selected table when you add a data form by using the Data Form Wizard: the primary column and a column that does not permit NULLs.
若要解决此问题，请在添加数据窗体时通过使用“数据窗体向导”选择所选表中的以下列：主列和不允许 NULL 的列。
To work around this problem, select the following columns of the selected table when you add a data form by using the Data Form Wizard: the primary column and a column that does not permit NULLs.
若要解决此问题，请在添加数据窗体时通过使用“数据窗体向导”选择所选表中的以下列：主列和不允许 NULL 的列。
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