问题描述
我正在编写一个存储过程，其中有一个名为 my_size 的输入参数，它是一个 INTEGER .我希望能够在SELECT语句的LIMIT子句中使用它.显然不支持此功能，有没有办法解决此问题?
I am writing a stored procedure where I have an input parameter called my_size that is an INTEGER. I want to be able to use it in a LIMIT clause in a SELECT statement. Apparently this is not supported, is there a way to work around this?
# I want something like:
SELECT * FROM some_table LIMIT my_size;
# Instead of hardcoding a permanent limit:
SELECT * FROM some_table LIMIT 100;
推荐答案
出现了搜索本文.我已经在下面粘贴了相关文本.
A search turned up this article. I've pasted the relevant text below.
http://forums.mysql.com/read. php?98,126379,133966#msg-133966
但是，我认为此bug应该引起注意，因为我不能 想象过程中准备好的语句将允许任何 过程编译时优化.我有种准备的感觉 语句在过程运行时进行编译和执行， 哪个概率会对效率产生负面影响.如果极限 子句可以接受正常的过程变量(例如，一个过程 参数)，那么数据库仍可以执行编译时 在过程中对其余查询进行优化.这 可能会更快地执行该过程.我不是专家 但是.
However, I think this bug should get some attention because I can't imagine that prepared statements within a procedure will allow for any procedure-compile-time optimizations. I have a feeling that prepared statements are compiled and executed at the runtime of the procedure, which probaby has a negative impact on efficiency. If the limit clause could accept normal procedure variables (say, a procedure argument), then the database could still perform compile-time optimizations on the rest of the query, within the procedure. This would likely yield faster execution of the procedure. I'm no expert though.
这篇关于在MySQL的LIMIT子句中使用变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！