When ON delete set NULL is active, when a record is deleted from the parent table, all records in the child table with matching foreign key values are set to NULL.
当ON DELETESETNULL规则被激活时，如果一条记录从父表中删除，子表中的所有记录以及匹配的外键值都被设置为NULL。
The combined record is much easier to use-you only have to check the PICTURE field to see if it's not null (which was the result of the LEFT OUTER JOIN).
而组合的记录使用起来要容易得多—只需检查PICTURE字段，查看它是否为空(这是LEFTOUTER JOIN的结果)。
The SIF record format also contains delta specific columns to assist in setting the indicator values of existing database records to NULL.
SIF记录格式还包含特定于delta的列，以协助将现有数据库记录的指示符值设置为NULL。
Note that the test for null values is gone from the for statement, because you want to handle that condition by writing a diagnostic record.
注意，对null值的检查从for语句中消失了，因为希望通过写诊断记录来处理这种情况。
The record header is followed by the data contents of the columns. Columns that are NULL are omitted.
记录头的后面是字段的内容，其中空字段被忽略。
When you delete a record, RFX sets all the fields to NULL as a reminder that the record is deleted and you must move off it.
当您删除记录时，RFX将所有字段设置为NULL，提醒您该记录已删除，您必须将其移走。
For each non-NULL variable-length field, the record header contains the length of the column in one or two bytes.
对于每个非空的变长字段，记录头使用一或两个字节包含了列的长度。
Config record handlers, like the record creation and merge handlers, return either a pointer to the new structure or NULL.
配置记录处理程序，比如记录创建和处理程序合并，返回一个指向新结构或NULL。
When we encounter a non-null node, we record the node's value.
当遇到非空节点时，记录节点的值。
When we encounter a non-null node, we record the node's value.
当遇到非空节点时，记录节点的值。
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