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- An index also affords Adaptive Server Anywhere a convenient means of enforcing a uniqueness constraint on the rows in a table. 索引还使Adaptive Server Anywhere能够方便地对表的行强制唯一性约束。
- Notice that the rows inserted from the Production.UnitMeasure table that did not violate the uniqueness constraint were successfully inserted. 请注意;从Production.;UnitMeasure表中插入的、不违反唯一性约束的行将成功插入。
- If the column is contained in a uniqueness constraint, a foreign key, or a primary key, then the constraint or key must be deleted before the column can be modified. 如果列包含在唯一性约束、外键或主键中,则必须删除约束或键后才能修改列。
- If the column is contained in any index, uniqueness constraint, foreign key, or primary key then the index, constraint, or key must be deleted before the column can be deleted. 如果列包含在任何索引、唯一性约束、外键或主键中,则必须删除索引、约束或键后才能删除列。
- This class can be used to identify a unique constraint among a set of elements. 此类可用于标识一组元素中的唯一约束。
- The Unique Constraint or Foreign Key Constraint dialog box is displayed. 即显示“唯一约束”或“外键约束”对话框。
- Index imposing the UNIQUE constraint on the column designated as the unique key column. 对于指定为唯一键列的列施加UNIQUE约束的索引。
- Add or drop PRIMARY KEY or UNIQUE constraints. 添加或删除PRIMARY KEY或UNIQUE约束。
- Unique constraints are also called keys. 唯一约束也称为键。
- However, changing the length of a variable-length column used in a CHECK or UNIQUE constraint is allowed. 但是,允许更改用于CHECK或UNIQUE约束中的长度可变的列的长度。
- This set of columns may be generated from a base table primary key, a unique constraint or a unique index. 这组列可以从基表主键、唯一约束或唯一索引生成。
- At least Arity + 1 examples are required to clearly show the uniqueness constraints. 要清楚地显示唯一性约束，至少需要“实参数量+1”个示例。
- All of the tables in the main data connection must contain a primary key, unique constraint, or unique index. 主数据连接中的所有表都必须包含一个主键、唯一约束或唯一索引。
- Columns of a unique index are allowed to be NULL, while columns in a unique constraint are not. 唯一索引的列可以为NULL,而唯一约束的列不能为NULL。
- In order to create a foreign key relationship, at least one of the two tables must have a primary key or unique constraint defined. 要创建外键关系,两个表中必须至少有一个定义了主键或唯一约束。
- 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PRIMARY KEY约束。
- 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PRIMARY KEY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。
- Create a unique constraint to ensure no duplicate values are entered in specific columns that do not participate in 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。
- When you attach a unique constraint to a column allowing null values, you ensure that at most one row will have a null value in the constrained column. 当将唯一约束附加到允许空值的列时,请确保在约束的列中最多有一行包含空值。
- Because the Regular Expression generator is not guaranteed to produce unique values, you cannot use it to fill a user-defined type column that has a unique constraint. 由于正则表达式生成器无法保证生成唯一值,因此您不能使用它来填充具有唯一约束的用户定义的类型列。
