Since this query contains no value predicate to restrict either the books or the authors table, DB2 has to perform a table scan on either of the two tables to read all author IDs.
由于该查询没有包含用来限制books或authors表的值谓词，因此DB 2必须在两个表上执行表扫描，以便读取所有author ID。
Since the response contains either the return value or an exception, two different methods can be invoked depending on the content of the message.
由于响应中会包含返回值或者异常，那么依照消息的内容可以调用两个不同的方法。
This means that if you have a single parameter value that contains a comma, it would be treated as if it consisted of two values.
如果有一个本身包含逗号的参数值，会把它当作两个值对待。
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