EXEC user-defined variable EXEC的用法和样例：
例句
- The value of a user-defined variable can be a literal or an expression.
用户定义变量的值可以是文字或表达式。 - The user-defined variables that are used in parameter bindings are usually defined with data types that are compatible with the data types of parameters to which they are mapped.
在参数绑定中使用的用户定义变量通常是以与映射到它们的参数的数据类型兼容的数据类型来定义的。
