修复了在复杂联接表的重复列名。
Fixed duplicate column name on complex joins of similar tables.
如何创造一套联接表的属性自动关联吗？
How to create an association that sets join table attributes automatically?
可从单个表或联接表复制。
将其他两个表中的主键列都复制到联接表中。
Copy the primary key columns from each of the other two tables to the junction table.
解释联接表的各种方法以及如何选择最佳方法。
Explains various ways to join tables and how to choose what option is best.
该表将成为联接表。
让查询和视图设计器决定是否应联接表的步骤。
Steps for allowing the Query and View Designer determine if tables should be joined.
希望通过在from子句中指定多个表来联接表。
You want to join tables by specifying multiple tables in the FROM clause.
指定即使某些行与相应表中的行不匹配，联接表也应包含这些行。
Specify that joined tables should include rows even when they do not match rows in the corresponding table.
您可能需要使用一个联接表设置一个多对多关系，这需要几个联接来确定某个电影的演员。
You would probably need to set up a many-to-many relationship with a join table, requiring several joins to determine the actors for a particular movie.
列出关于使用联接查询多个表的主题，例如如何创建外部联接和如何自动联接表。
Lists topics on using joins to query multiple tables, such as how to create outer joins and how to join tables automatically.
此示例程序可以为您提供UNLOAD实用程序不支持的其他SQL功能(比如通过联接表获得的数据)。
This sample program can give you additional SQL capabilities (like data obtained by joining tables) that are not supported with the UNLOAD utility.
如果我要使用一个关系表结构来设计这个关系，至少需要3个表：第3表将是链接一个“多对多”关系的联接表。
If I were to use a relational table structure to design this relationship, I'd need at least three tables: the third being a join table linking a many-to-many relationship.
从性能的角度来看，这被认为是一个非常有效的联接操作，因为通过贯穿唯一索引的唯一访问扫描内部表的成本是最优的。
From the performance perspective, this is considered a very efficient join operation, because the cost for scanning the inner table is optimal via unique access through a unique index.
对于更复杂的问题，必须联接多个表，但标准化允许您以复杂的方法执行。
For a more complex question, you have to join multiple tables, but normalization allows you to do that in complex ways.
重新排序和重新组合谓词是基于谓词的种类(本地或联接)和表引用。
Predicates are reordered and regrouped based on the kind of predicate (local or join) and the table reference.
在撰写本文时，YQL还不允许您通过公用键(一个联接)来链接表，只允许您在一个查询(一个子查询)内使用另一个查询的结果。
As of this writing, YQL doesn't allow you to link tables through common keys (a join), but only permits you to use the results of one query inside another (a subquery).
现在您有了一个关于表和如何访问信息(在这种情况下通过索引)的概述，您已准备好仔细查看正在使用的联接方法。
Now that you have an overview of the tables and how the information is accessed (via indexes in this case), you are ready take a closer look at the join methods that are used.
传统RDBMS的最大价值在于，它可以将单独的表联接在一起，从而创建其中所包含数据的不同视图。
The greatest value of a traditional RDBMS comes from its ability to join individual tables together to create different views of the data contained therein.
因此，在决定选择哪种联接方法时，优化器为内部表扫描平衡排序成本和性能优势以便促进决策。
Therefore, when deciding which join method to choose, the optimizer balances the sort cost and the performance benefit for the inner table scan to drive the decision.
在缺少当前统计的情况下，优化器选择对参与联接的两个表进行表扫描。
The optimizer, in the absence of current statistics, is choosing to do a table scan on both tables involved in the join.
然而，合并扫描联接的好处是不必反复地扫描内部表因为其为嵌套循环联接工作。
However, the benefit of the merge scan join is that the inner table does not have to be scanned repeatedly as it does for nested loop joins.
现在，当同一个查询运行时，生成的原生sQL是单个选择语句，在语句在数据库层联接来自不同目录的两个表，如图10所示。
Now, when the same query is run, the native SQL that is generated is a single select statement joining the two tables from the different catalogs at the database tier as shown in Illustration 10.
也就是说，联接操作的内部表将被扫描8次，来自外部输入的 8 个合格的记录每个都将被扫描一次。
That is, the inner table of the join operation will be scanned eight times, once for each of the eight qualifying records from the outer input.
在采购订单和产品表之间创建联接以获取产品详细信息。
Create a join between the purchase order and the product table to get product details.
通常您在两个表之间一个或多个列上有一个联接，在这些表中，在一个或多个不同列上使用过滤器。
Often you have a join between two tables on one or more columns, with filters on one or more different columns in those tables.
通常情况下，在外部输入的基数显然不小且对于内部表没有一种有效的访问方法时，优化器会选择合并扫描联接。
Typically, the optimizer chooses merge scan join when the cardinality of the outer input is not obviously small and there is no efficient access method for the inner table.
作为转换的一部分，优化器还决定正确的表联接顺序，重写表达式，并从SQL中消除任何冗余。
As part of the transformation, the optimizer also determines the correct table join order, rewrites expressions, and eliminates any redundancy from the SQL.
也就是说，进入第二个表引用和第三个表引用的探测只将有效地定位匹配联接条件的记录。
That is, each probe into the second table reference and the third table reference would efficiently locate the only record that matches the join condition.
对于客户类型来说，在JLT_T077D上使用其相应的支持数据来联接来自E2KNA1M 005表的列ktokd，使用KTOKD作为联接键。
For customer type, join the column KTOKD from the E2KNA1M005 table with its corresponding supporting data in JLT_T077D, using KTOKD as the join key.
应用推荐