问题描述
我正在尝试为PDO语句的结果编写一个迭代器,但我找不到任何重绕到第一行的方法。我想避免调用fetchAll并存储所有结果数据的开销。
I'm trying to write an iterator for results from a PDO statement but I can't find any way of rewinding to the first row. I would like to avoid the overhead of calling fetchAll and storing all the result data.
// first loop works fine
foreach($statement as $result) {
// do something with result
}
// but subsequent loops don't
foreach($statement as $result) {
// never called
}
有没有办法重置声明或寻找第一行?
Is there some way of reseting the statement or seeking the first row?
推荐答案
我很确定这是依赖于数据库的。因此,您应该尽量避免这种情况。但是,我认为您可以通过启用来实现您的目标。如果这不起作用,您始终可以使用。这两种解决方案都会对您的应用程序性能产生影响,因此如果结果集很大,请三思而后行。
I'm pretty sure this is database dependent. Because of that, it is something you should try to avoid. However, I think you can achieve what you want by enabling buffered queries. If that doesn't work, you can always pull the result into an array with fetchAll
. Both solutions have implications for your applications performance, so think twice about it, if the resultsets are large.
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