primary key

US 
UK 
  • un.主关键字；主码
  • Web主键；主表的主键信息；主键约束

E-C

Web Definition

un.
1.
主关键字
2.
主码

Sample Sentence

Definition:
AllAll,主关键字主关键字,主码主码,主键主键,主表的主键信息主表的主键信息,主键约束主键约束
Category:AllAll,OralOral,WrittenWritten,TitleTitle,TechnicalTechnical
Source:AllAll,DictionaryDictionary,WebWeb
Difficulty:AllAll,EasyEasy,MiddleMiddle,HardHard
1.
However, you cannot change the length of a column defined with a PRIMARY KEY constraint.
但是，不能更改使用PRIMARYKEY约束定义的列长度。
dàn shì , bù néng gēng gǎi shǐ yòng PRIMARYKEY yuē shù dìng yì de liè cháng dù 。
msdn2.microsoft.com
2.
An index created as part of a PRIMARY KEY or UNIQUE constraint is automatically given the same name as the constraint name.
创建为PRIMARYKEY或UNIQUE约束的一部分的索引将自动给定与约束名称相同的名称。
chuàng jiàn wèi PRIMARYKEY huò UNIQUE yuē shù de yí bù fen de suǒ yǐn jiāng zì dòng gěi dìng yǔ yuē shù míng chēng xiāng tóng de míng chēng 。
technet.microsoft.com
3.
If CLUSTERED is specified for a UNIQUE constraint and a PRIMARY KEY constraint is also specified, the PRIMARY KEY uses NONCLUSTERED.
如果为UNIQUE约束指定了CLUSTERED，并且指定了PRIMARYKEY约束，则PRIMARYKEY使用NONCLUSTERED。
rú guǒ wèi UNIQUE yuē shù zhǐ dìng le CLUSTERED , bìng qiě zhǐ dìng le PRIMARYKEY yuē shù , zé PRIMARYKEY shǐ yòng NONCLUSTERED 。
technet.microsoft.com
4.
In addition, the CREATE TABLE and ALTER TABLE statements can be used to set locking granularity on PRIMARY KEY and UNIQUE constraints.
另外，CREATETABLE和ALTERTABLE语句还可用于设置PRIMARYKEY和UNIQUE约束的锁定粒度。
lìng wài , CREATETABLE hé ALTERTABLE yǔ jù hái kě yòng yú shè zhì PRIMARYKEY hé UNIQUE yuē shù de suǒ dìng lì dù 。
technet.microsoft.com
5.
This includes both DDS-created files and SQL indexes as well as physical files with a Primary Key constraint.
这包括DDS创建的文件和SQL索引，以及带有PrimaryKey约束的物理文件。
zhè bāo kuò DDS chuàng jiàn de wén jiàn hé SQL suǒ yǐn , yǐ jí dài yǒu PrimaryKey yuē shù de wù lǐ wén jiàn 。
www.ibm.com
6.
A unique index , UNIQUE constraint, or PRIMARY KEY constraint cannot be created if duplicate key values exist in the data .
如果数据中存在重复的键值，则不能创建唯一索引、UNIQUE约束或PRIMARYKEY约束。
rú guǒ shù jù zhōng cún zài chóng fù de jiàn zhí , zé bù néng chuàng jiàn wéi yī suǒ yǐn 、 UNIQUE yuē shù huò PRIMARYKEY yuē shù 。
www.bing.com
7.
Identity columns are commonly used in conjunction with PRIMARY KEY constraints to serve as the unique row identifier for the table.
标识列通常与PRIMARYKEY约束一起用作表的唯一行标识符。
biāo shí liè tōng cháng yǔ PRIMARYKEY yuē shù yì qǐ yòng zuò biǎo de wéi yī xíng biāo shí fú 。
msdn2.microsoft.com
8.
PRIMARY KEY columns cannot be modified through an UPDATE statement if the member tables have.
列，则PRIMARYKEY列无法通过UPDATE语句进行修改。
liè , zé PRIMARYKEY liè wú fǎ tōng guò UPDATE yǔ jù jìn xíng xiū gǎi 。
msdn2.microsoft.com
9.
NULL can be specified in ALTER COLUMN to force a NOT NULL column to allow null values, except for columns in PRIMARY KEY constraints.
在ALTERCOLUMN语句中指定NULL，可以强制NOTNULL列允许空值，但PRIMARYKEY约束中的列除外。
zài ALTERCOLUMN yǔ jù zhōng zhǐ dìng NULL , kě yǐ qiáng zhì NOTNULL liè yǔn xǔ kōng zhí , dàn PRIMARYKEY yuē shù zhōng de liè chú wài 。
msdn2.microsoft.com
10.
The UNIQUE or PRIMARY KEY constraint can contain a computed column as long as it satisfies all conditions for indexing.
UNIQUE或PRIMARYKEY约束只要满足所有索引条件，就可以包含计算列。
UNIQUE huò PRIMARYKEY yuē shù zhǐ yào mǎn zú suǒ yǒu suǒ yǐn tiáo jiàn , jiù kě yǐ bāo hán jì suàn liè 。
msdn2.microsoft.com