what is primary dns

primary key is a selected candidate key. I understand what is a candidate keyTake a look at the question firstIn the SQL Server database, there is a student information table as follows. In this table, the attribute set that cannot be used as the candidate key

Mysql index types: PRIMARY, INDEX, UNIQUE, FULLTEXT, and SPAIAL? What are the applicable scenarios ?, Fulltextspaial Mysql common indexes include: primary key index, unique index, common index, full-text index, and composite index.Primary key (primary key index)Alter table 'table _ name' add

the network service. In"/etc/resolv. conf "the configured nameserver information is also lost.Processing Find the corresponding Nic configuration file "/etc/sysconfig/network-scripts/ifcfg-eth Here, For example, if the first network adapter in the system is eth0, its configuration file is/etc/sysconfig/network-scripts/ifcfg-eth0.vim /etc/sysconfig/network-script

;Now insert (1, ' xiaohong ') data, found error, error prompt (primary key repeat input ' 1 '), prove that when insert inserted the same primary key will be error.Now we have to replace the statement test will not error, execution successCheck our table information and find that the previous record (1, ' Xiaozhang ') has been replaced by (1, ' Xiaohong '),Proof that we inserted the same

Scene:1. The functions in the ctype.h in the standard library are used for 1-byte judgments, but the parameters are int, which can easily lead to misuse.Isalphaiscntrlisdigitisgraphisprintispunctisspaceisxdigit Isalnumislowerisupperint isspace (int ch);The most disgusting is the VC + + implementation will be more than 1 bytes of value will directly crash, GCC will not!!!#if defined (_DEBUG) extern "C" int __cdecl _chvalidator ( int C, in

Small white is a loyal user of Emacs, on the CentOS server also need to compile and install a Emacs for their own use. Because of the use of a lot of Emacs plug-ins, each time it is very slow to start, almost 5s or so to open a file (let everyone mistakenly think server configuration sucks it). In the speed of opening the file with Vim some gap, vim open file is

How is Dynamic DNS resolution done? This question is not related to PHP, but I don't know which section is appropriate. --------------------------------------------- If you ping some large websites, such as YOUKU.COM,GOOGLE.COM.HK, you will see different IPs after each resolution. This

. Https://bitcoin.org/en/glossary/hard-fork The blockchain has a permanent divergence, and after the new consensus rule is released, some nodes that are not upgraded cannot verify the chunks that have been upgraded by the node, usually hard forks occur. The definition of a soft fork is this: A temporary fork in the block chain which commonly occurs when miners using non-upgraded nodes violate a new consensu

What should I do if an error occurs when setting the db2 primary key? The following describes how to solve the problem of not allowing you to set the db2 primary key. We hope this will help you learn how to set the db2 primary key. Set empno as the primary key Db2 => alter t

use the order by clause, what sort of results are returned by the query? If the order by clause is not specified, the query results are in an uncertain order. It must be based on the primary key. The query optimizer generates an execution plan based on the actual situation. Sorting costs a lot, and the cost may not be small. If the order by clause

Today, someone asked me about the physical order and logical order, just like this topic. Page fragmentation: the next page of the leaf page in the iam page is different from the next page in the page header. Logical Order: The order in which the leaf pages of the index are formed through the previous page. Physical Order: The order allocated in IAM DROP TABLE dbo.t_indexgoCREATE TABLE t_index (id INT PRIMARY