3 Min
Summary of differences between null and empty string '' in Oracle
Q: What is NULL? Answer: When we don't know what data there is, that is unknown, NULL can be used. We call it empty. In ORACLE, the length of a table column with a null value is zero. ORACLE allows fields of any data type to be empty, except for the following two cases: 1, the primary key field (primary key), 2. Fields with NOT NULL restriction conditions have been added during definition
Answer: When we don't know what data there is, that is unknown, NULL can be used. We call it empty. In ORACLE, the length of a table column with a null value is zero.
ORACLE allows fields of any data type to be empty, except for the following two cases:
1, the primary key field (primary key),
2. Fields with NOT NULL restriction conditions have been added during definition
By Nick Zhao
Aug 27 2021
6 Min
Backup Copy and Offsite DR with Vinchin Backup & Recovery
Backup copy is a feature which can be used to make duplicate versions of your backup data to a secondary storage or location. The copied data is usually of the same version, size and type as your original backup data, and can be used to restore the backup data from any accidental deletion and corruption.
By Nick Zhao
Aug 26 2021
6 Min
Backup your VMware virtual machines with Vinchin Backup & Recovery
This article introduces how to back up VMware virtual machines with Vinchin Backup & Recovery. Go to VM Backup -> Backup page to start creating a new backup job. Expand the VMwre vSphere virtual infrastructure and select target VMs that you want to backup, multiple VMs can be selected to add into one job.
By Nick Zhao
Aug 26 2021
4 Min
On-Prem Archive and Cloud Archive with Vinchin Backup & Recovery
Vinchin archive feature allows users to archive backup data to both on-premise and cloud including Alibaba, AWS S3 and other S3 compatible cloud storages, helping to better keep data in long term for later use.
By Nick Zhao
Aug 26 2021
4 Min
Rsync + inotify data synchronization
Rsync + inotify requires: To synchronize / data / book / of the source server 192.168.1.100 to / data / book / of the target server 192.168.1.101, real-time synchronization is required. The first part: operate on the target server 192.168.1.101. First, install Rsync server 1 on the target server, turn off selinux2, turn on firewall TCP 873 port (Rsync default port) 3, install
By Nick Zhao
Aug 26 2021
2 Min
Copy VMware virtual machine from one computer to another
CentOS is created on a computer using a virtual machine. If you want to run CentOS on the virtual machine at home, you don't have to reinstall and wait for a long time. You can use the. VMX files and. Vmdk files generated by installing CentOS on the virtual machine, copy them to the USB flash disk, and then import them to the new computer. It's easy and labor-saving. 1、 What is a VMX file? VMX file is the configuration file of virtual machine system.
By Nick Zhao
Aug 25 2021
2 Min
How to restore deleted DNS SRV records?
SRV (Service Record) is a type of resource record supported in the database of the DNS server. It records services running on each computer. What is SRV record? Generally, it is an application when set up for Microsoft's Active Directory.
By Nick Zhao
Aug 23 2021
5 Min
DB2 backup and archive setting
Similar to Oracle, DB2 is also divided into two modes, log cycle vs archive log, which is non-archive and archive mode. The two modes are briefly introduced below. Circular logging is the default mode, that is, non-archive mode. This mode only supports backup offline, and DB2 needs to stop the service during the backup process.
By Nick Zhao
Aug 17 2021
1 Min
How to use DB2 SELECT query result to create table
Sometimes we may want to use DB2 to define the result of the query as another table, but since DB2 does not support to define a table with a method like create table as select from Oracle, it might be more difficult. In this blog, we summarize 3 ways to define DB2 tables.
By Nick Zhao
Aug 11 2021
1 Min
How to export Excel spreadsheet report by ZABBIX
The preparation of operation and maintenance report, patrol report, operation and maintenance asset statistics, operation and maintenance performance report are all one of the normal work of operation and maintenance personnel. How to write operation and maintenance report efficiently, generate operation and maintenance report quickly, and liberate the time of operation and maintenance personnel, we need the corresponding operation and maintenance tools. Netpod extracts data from ZABBIX and exports the data that operation and maintenance personnel want,
By Nick Zhao
Jul 19 2021
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