对于主键约束，有些数据库具有不同的功能。
Some databases have different functionality for primary key constraints.
对于主键约束，有些数据库具有不同的规则。
Some databases have different rules for primary key constraints.
引用唯一或主键约束，必须是父表中已经定义的。
The referenced unique or primary key constraint on the parent table or view must already be defined.
当定义一个主键约束时，联邦系统自动创建一个惟一的索引规范。
When a primary key constraint is defined, the federated system automatically creates a unique index specification.
有关数据库如何使用主键约束的详细信息，请查阅数据库文档。
Consult your database documentation for details about how your database works with primary key constraints.
找到那些惟一/主键约束名，禁用这些约束然后再次删除表空间。
Find the constraint name for the unique/primary key, disable the constraint and drop the tablespace again.
可将多个唯一约束附加到表，但是只能将一个主键约束附加到表。
You can attach multiple unique constraints to a table, whereas you can attach only one primary key constraint to a table.
可将唯一约束附加到允许空值的列，但是只能将主键约束附加到不允许空值的列。
You can attach unique constraints to columns that allow null values, whereas you can attach primary key constraints only to columns that do not allow null values.
如图16所示，两个示例记录中的批量加载操作结果被发送给拒绝链接，因为它们违反唯一的主键约束。
As shown in Figure 16, the bulk load operation results in two of the sample records being sent to the reject link because they violate the unique primary key constraint.
要确保指定的键在特定时间段内是惟一的，可以指定主键约束BUSINESS_TIMEWITHOUTOVERLAPS作为包含其他键的列表中的最后一项。
To enforce that specified keys are unique with respect to the specific time period, specify the primary key constraint BUSINESS_TIME WITHOUT OVERLAPS as the last item with the list of other keys.
主键、引用完整性和检查约束。
TABLESKEYUNIQUE该表所定义的唯一性（与主键不同）约束的数量db2 "select tabname, keyunique from syscat.tables where keyunique > 0"
SYSCAT.TABLES KEYUNIQUE Number of unique constraints (other than primary key) defined on this table db2 "select tabname, keyunique from syscat.tables where keyunique > 0"
这两个数据库系统都支持主键，以及支持加速查询和约束输入的键索引。
The two database systems support primary keys, along with key indices that allow you to speed up queries and constrain input.
如果表的主键或惟一性约束中指定了这个列，那么不允许使用这个子句(SQLSTATE 42831)。
This clause is not allowed if the column is specified in the primary key, or in a unique constraint of the table (SQLSTATE 42831).
约束支持主键、外键、惟一和非空约束。
Constraints Supports, primary, foreign, unique, not null constraint.
它们由逻辑数据模型转换而来，其中实体和关系转换为表、列、主键、外键以及约束。
They are transformations of logical data model where the entities and relationships are transformed into tables, columns, primary keys, foreign keys, and constraints.
索引扫描实际上是对父表进行主键查找，并完成外键约束验证。
The latter is actually a primary key lookup against the parent table and constitutes the foreign key constraint verification.
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.
ActiveRecord会为不同的任务变量使用主键和副键，它们都是作为数据库的约束而定义的。
ActiveRecord USES primary and foreign keys for a variety of tasks, and both are defined as constraints on your database.
ccd表中必须有惟一性约束——可以通过主键或者源表或ccd表上的惟一索引实现。
Uniqueness in the CCD table must be enforced — either by a primary key or unique index on the source table or CCD table.
也可以使用系统编目视图来检索关于NOT NULL、惟一、主键、外键和表检查约束的信息。
You can also use the system catalog views to retrieve information about NOT NULL, unique, primary key, foreign key, and table check constraints. For example.
tabconst为每个唯一性(U)、主键(p)、外键(f)或者表检查(K)约束保持一个行db2select constname,tabname,typefrom syscat . tabconst。
Syscat.tabconst Contains a row for each unique (u), primary key (p), foreign key (f), or table check (k) constraint db2 select constname, tabname, type from syscat.tabconst.
由于其在关系型数据库中的重要性，主键是所有键和约束里最基础的方面。
Due to their importance in relational databases, Primary keys are the most fundamental aspect of all keys and constraints.
表必须具有相同的主键、唯一索引或唯一约束。
Tables must have the same primary key, unique index, or unique constraint.
唯一约束是表的主键，因此不能移除。
Can't remove unique constraint since it's the primary key of a table.
唯一约束可以保证在特定的列中没有重复值并允许您定义一个主键。
A Unique constraint guarantees that there are no duplicates in a specific column and allows you to define a primary key.
创建唯一约束可确保在不参与主键的特定列中不输入重复值。
Create a unique constraint to ensure no duplicate values are entered in specific columns that do not participate in a primary key.
主键是确保每个表都不包含重复行的约束。
A primary key is a constraint that assures that each table contains no duplicate rows.
当两个相关列都是主键或都具有唯一约束时，将创建一对一关系。
A one-to-one relationship is created if both of the related columns are primary keys or have unique constraints.
这种约束旨在用于主键列。
Such a constraint is intended to be used with primary key columns.
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