有几个重载版本的 DAYS（）函数，接受不同数据类型的参数： DATE ， TIMESTAMP 和 VARCHAR 。当您使用无类型参数标记（ DAYS（？））时，查询编译器无法确定查询中要使用的函数的版本。

There are several overloaded versions of the DAYS() function, accepting parameters with different data types: DATE, TIMESTAMP, and VARCHAR. When you use an untyped parameter marker (DAYS(?)) the query compiler is unable to determine which version of the function to use in the query.

您可以明确指定参数数据类型进行编译： DAYS（CAST（？AS TIMESTAMP））。或者，如果您使用最近的DB2 for LUW版本（9.7及更高版本），则可以设置DB2注册表变量：

You can specify the parameter data type explicitly for compilation: DAYS(CAST(? AS TIMESTAMP)). Alternatively, if you are using a recent DB2 for LUW version (9.7 and higher) you can set the DB2 registry variable:

db2set DB2_DEFERRED_PREPARE_SEMANTICS=YES

告诉编译器它应该推迟PREPARE调用，直到查询执行时间参数数据类型是已知的。

to tell the compiler that it should defer the PREPARE call until the query execution time, when parameter data types are already known.