mysql - mysql 中 ELSE IF block 中的游标声明？

Question

我想知道，我们可以在 ELSE IF block 中声明游标吗？当我这样做时，我发现错误在“声明”之前缺少子句或其他元素。我的代码是

 if State is NOT NULL
    then
    declare t cursor for select *from student;//this line has error 
    declare continue handler for NOT FOUND set str=1;
    else
    declare t cursor for select *from student;
    end if;

为什么？？

Answer 1

答案是否。 manual明确地说:

Cursor declarations must appear before handler declarations and after variable and condition declarations.

类似[bug: 15809] (最终不是)被报告但它以以下答案关闭:

Thank you for a problem report. Sorry, but I do not think it is a bug. The problem is that cursor should be declared, and all declarations are at the beggining of SP or a block.

Please, read (http://dev.mysql.com/doc/refman/5.0/en/cursors.html):

"Cursors must be declared before declaring handlers, and variables and conditions must be declared before declaring either cursors or handlers."

And, even more clearly (http://dev.mysql.com/doc/refman/5.0/en/declare.html):

"The DECLARE statement is used to define various items local to a routine: local variables (see Section 17.2.9, “Variables in Stored Procedures”), conditions and handlers (see Section 17.2.10, “Conditions and Handlers”) and cursors (see Section 17.2.11, “Cursors”). SIGNAL and RESIGNAL statements are not currently supported.

DECLARE may be used only inside a BEGIN ... END compound statement and must be at its start, before any other statements."

So, it is not a bug, but a documented behaviour.