约束有两种类型：表级约束和列约束。
Constraints come in two types: table-level constraints and column constraints.
换句话说，模式并不等同于sql列约束。
In other words, schemas are not the equivalent of SQL column constraints.
这些规则提供了更详细的信息，是关于存在一个昵称各个列的关系和约束。
These rules provide more detailed information about the relationships and restrictions that exist on the columns of a nickname.
强拍与约束音系学是建立在超音段音系学基础上的理论，与语音配列的关系十分密切。
Beats-and-Binding Phonology, a theory incorporated in suprasegmental phonology, is closely related to phonotactics.
在这种情况中，你把文档添加到模型的每一个元素中，包括每个列，每个表，每个约束和每个触发器。
In this activity, you add documentation to every element in the model, including every column, every table, every constraint, and every trigger.
在这个语法示例中，必须定义一个新列或者定义一个表级约束。
In this syntax example, you must either define a new column or define a new table-level constraint.
为列定义的所有默认约束必须相同。
Any default constraints defined for columns must be the same.
我所能获取的列太多，又很容易遗漏重要的结构化数据库特性，比如索引或空约束。
I can fetch too many columns, or leave off important structural database features, like indexes or null constraints.
用户可以使用检查约束来加强对xml列的验证。
A user can enforce validation on an XML column using check constraints.
尽量减少表上的触发器、检查和外键约束以及生成的列。
Minimize the triggers, CHECK and foreign key constraints, and generated columns for the table.
有时候您希望更改这种顺序或可能希望只为具有NOT NULL约束的列指定值。
Sometimes you may want to change this order or perhaps only specify values for columns that have NOT NULL constraints.
昵称可以包含列、统计信息、索引或信息约束。
Nicknames can have columns, statistics, indexes, or information constraints.
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.
这意味着表必须有一个或多个列级或表级约束。
This implies that the table must have one or more columns or table-level constraints.
您可能理解列定义的含义，但是可能不理解约束的意义。
You probably understand what is meant by a column definition, but you might not understand the idea of a constraint.
在XForms模型中，xfg生成xforms绑定属性形式的数据约束，它与数据库元数据相对应，比如列类型、长度、是否是必需的，等等。
In the XForms model, XFG generated data constraints as XForms bind attributes which correspond to database metadata, such as column type, length, required, and so on.
接下来，在编辑器中选择新添加的外键约束，并使用Properties视图指定关键列。
Next, select the newly added foreign key constraint in the editor and specify the key columns using the Properties view.
启用Soft RI后，确保得到了约束中所有列的适当统计数据。
After enabling Soft ri, ensure that appropriate statistics are collected on all columns in the constraint.
现在，添加一个新约束，以便在将一个列设为privacydata时检查是否存在一个masking方法。
Now, follow these steps to add a new constraint to check for the existence of a masking method if a column is set as privacy data
Finishing约束的状态是NU（St列）。
表items和SUPPLIERS分别在列item_id和suppl_id上定义了检查约束。
Both tables ITEMS and SUPPLIERS have check constraints defined on columns item_id and suppl_id respectively.
Checkconstraints视图—允许添加表及其列的检查约束。
Check constraints view a "Allows adding check constraints for a table and its columns."
COLCHECKS为表检查约束所引用的每个列保持一个行db2select constname,tabname,colname,usagefrom syscat.colchecks
SYSCAT.COLCHECKS Contains a row for each column that is referenced by a table check constraint db2 select constname, tabname, colname, usage from syscat.colchecks
一种解决方法是给从BEFORE INSERT触发器取得值的NOT null列提供默认值，这样就不会违反约束。
A workaround to this is to supply a default value to the not NULL column whose value comes from a BEFORE INSERT TRIGGER, so that the constraint is not violated.
请按清单7所示的顺序将字段添加到这个块(这些约束不影响列在表中的顺序—只影响在视图中的顺序)。
Add the fields to this block in the order shown in Listing 7. (These constraints don't affect the order of the columns in the table - just the view.)
这可以采用添加列、更改列的数据类型、添加约束或者甚至删除列的方式来实现。
This can take the form of adding a column, changing the data type for a column, adding a constraint, or even deleting a column.
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).
约束通过某种方式对列或表进行限制。
A constraint limits either a column or a table in some manner.
例如，如果一个BEFORE触发器给一个NOTnull列提供值，那么先执行BEFORE触发器，给列提供值，所以不会违反NOT NULL约束。
For example, if a before trigger supplies value to a NOT NULL column, then the before trigger is executed first and a value is supplied to the column so that the NOT NULL constraint isn't violated.
itemNumber列提供了每个商品（或列）的惟一标识，它上面还有列级约束，强制要求提供正确的值（NOT NULL）。
The itemNumber column provides a unique identity for each item (or row) and has an attached column-level constraint that enforces a valid value to always be supplied (NOT NULL).
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