这两个存在检查为何不好？
支持文件存在检查和url检查时捷径更新数据库。
Support file existence checking and URL checking when updating shortcut to database.
下图展示了主要服务器与HDR次要节点，以及日志暂存在检查点期间的工作步骤。
The below diagram represents primary and HDR secondary nodes, and steps of working log staging during checkpoint.
因此，如果没有更多注释，这里有一种更好的方法，可用这种方法来处理通常用来处理条件更新和执行存在检查的显式方式。
So, without further comment, here is better way to handle explicit way to handle conditional updates and do existential checks in general.
我无法理解开发人员为何用下方所示方式编写存在检查(existential check)，但是因为他们这样做了，所以我们就来讨论它。
I cannot fathom why developers write existential checks in the way I show below, but since they do, I will discuss it.
对他的重型卡车的检查显示有3处刹车存在问题。
An inspection of his rig showed that three of the brakes were faulty.
但就在不到一个月前，检查人员发现消防安全系统存在重大问题，于是将开放时间再次推迟到2013年。
But less than a month before hand, inspectors found significant problems with the fire safety system and push the opening back again to 2013.
学生完成作业后，他们把它保存在微信里。所以我可以随时随地用电脑或手机检查他们的作业。
When students finish the homework, they keep it on WeChat. So I can check their homework everywhere using my computer or mobile phone.
今年几起严重的客户和雇员资料泄漏事件使得管理者们匆忙仔细检查他们复杂的信息系统和业务流程，以寻找可能存在的安全隐患。
Several massive leakages of customer and employee data this year have left managers hurriedly peering into their intricate IT systems and business processes in search of potential vulnerabilities.
无意义介导的衰变检查是否存在过早的无意义密码子。
Nonsense-mediated decay checks for the presence of premature nonsense codons.
检查文件中是否存在欺诈性的首选项或可检查的事务。
Review the file for any fraudulent preferences or reviewable transactions.
如果存在问题，检查项目属性，以确保正确地设置了源路径和类路径。
If there is a problem, check the project properties to make sure the source path and classpath are set properly.
检查工作项是否存在。
读取初始化文件后，将检查是否存在新的电子邮件。
After reading the initialization file, the presence of new E-mail is checked.
以上代码首先检查是否存在实例。
第一次，您必须检查是否存在存档文件。
The first time, you must check if the archived file is present.
浏览器将检查是否存在新的清单文件。
The browser will check to see if there is a new manifest file.
您已经看到了当 URL不存在时应该如何检查 404错误。
You've already seen how to check for a 404 error when a URL doesn't exist.
PL运行时，它首先检查MANIFEST，并检查是否存在项目所需的所有文件。
When Makefile.PL is run, it first examines MANIFEST, and checks that all the files required for the project are present.
如何检查是否存在分布统计信息？
检查目标字段是否存在。
该目的地应该存在—selpg不检查这一点。
The destination should exist — selpg does not check for this.
首先检查start变量是否存在。
You begin by checking to see whether the start variable exists.
如果在主键列上存在信息检查约束，那么应该在它们相应的外键列上指定信息检查约束。
If informational check constraints exist on the primary key column, you should explicitly specify informational check constraints on their corresponding foreign key columns. For example.
首先，Drupal检查url路径中是否存在节点类型。如果存在，还要检查发出这一请求的用户是否有权创建新节点。
First, Drupal checks to determine whether the node type in the URL path exists and, if it exists, if the user making this request has the authority to create a new node.
可以在VIOS上使用lsdev命令检查是否存在此设备。
You can confirm the existence of this device with the lsdev command on the VIOS.
所以，如果您肯定那个空数据库中存在数据，请检查是否有录入错误。
So, if you are sure there was data in that empty database, check for typing errors.
检查是否存在要传递的消息，如果存在，则传递这些消息。
Checks whether or not messages exist for delivery and, if so, delivers them.
这时会生成一个检验报告，该报告用于检查是否存在与部署有关的错误。
A verification report will be generated which can be used to check for any problems with the deployment.
这时会生成一个检验报告，该报告用于检查是否存在与部署有关的错误。
A verification report will be generated which can be used to check for any problems with the deployment.
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