数据库只取出一部分的有关问题
数据库只取出一部分的问题
我现在有一张表，属性有fid, content, time 。fid是好友的id, content是好友说的话，每个好友可以说很多句话，好友也有很多，现在假设有很多好友，每个好友说了很多话，怎么能按时间取出任意多的数据。我现在只能foreach一下fid然后在push到一个新数组里面，然后再按time排序，然后取出期中的一些，但是这样效率太低了，有没有别的方法呢
------解决方案--------------------
是全部取出数据，还是取指定个数的数据？
------解决方案--------------------
select fid,content,time from table order by time desc
------解决方案--------------------
根据时间排序啊
order by time
------解决方案--------------------
建议你贴出你的表结果和你的代码，这样别人才能知道你想要干什么。
------解决方案--------------------
关键代码发出来看一下
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1670
14
1428
52
1329
25
1274
29
1256
24
What is the difference between using foreach and iterator to delete elements when traversing Java ArrayList?
Apr 27, 2023 pm 03:40 PM
1. The difference between Iterator and foreach is the polymorphic difference (the bottom layer of foreach is Iterator) Iterator is an interface type, it does not care about the type of collection or array; both for and foreach need to know the type of collection first, even the type of elements in the collection; 1. Why is it said that the bottom layer of foreach is the code written by Iterator: Decompiled code: 2. The difference between remove in foreach and iterator. First, look at the Alibaba Java Development Manual, but no error will be reported in case 1, and an error will be reported in case 2 (java. util.ConcurrentModificationException) first
How to determine the number of foreach loop in php
Jul 10, 2023 pm 02:18 PM
The steps for PHP to determine the number of the foreach loop: 1. Create an array of "$fruits"; 2. Create a counter variable "$counter" with an initial value of 0; 3. Use "foreach" to loop through the array, and Increase the value of the counter variable in the loop body, and then output each element and their index; 4. Output the value of the counter variable outside the "foreach" loop to confirm which element the loop reaches.
PHP returns an array with key values flipped
Mar 21, 2024 pm 02:10 PM
This article will explain in detail how PHP returns an array after key value flipping. The editor thinks it is quite practical, so I share it with you as a reference. I hope you can gain something after reading this article. PHP Key Value Flip Array Key value flip is an operation on an array that swaps the keys and values in the array to generate a new array with the original key as the value and the original value as the key. Implementation method In PHP, you can perform key-value flipping of an array through the following methods: array_flip() function: The array_flip() function is specially used for key-value flipping operations. It receives an array as argument and returns a new array with the keys and values swapped. $original_array=[
Monotonic clock processing of time package
Aug 04, 2023 pm 05:45 PM
Today we are mainly going to take a look at the time application method of golang time package. The general rule between the two is that "wall time" is used to tell time, and "monotonic clock" is used to measure time; there are other clock processing methods.
What is the difference between foreach and for loop
Jan 05, 2023 pm 04:26 PM
Difference: 1. for loops through each data element through the index, while forEach loops through the data elements of the array through the JS underlying program; 2. for can terminate the execution of the loop through the break keyword, but forEach cannot; 3. for can control the execution of the loop by controlling the value of the loop variable, but forEach cannot; 4. for can call loop variables outside the loop, but forEach cannot call loop variables outside the loop; 5. The execution efficiency of for is higher than forEach.
PHP returns the current element in an array
Mar 21, 2024 pm 12:36 PM
This article will explain in detail about the current element in the array returned by PHP. The editor thinks it is very practical, so I share it with you as a reference. I hope you can gain something after reading this article. Get the current element in a PHP array PHP provides a variety of methods for accessing and manipulating arrays, including getting the current element in an array. The following introduces several commonly used techniques: 1. current() function The current() function returns the element currently pointed to by the internal pointer of the array. The pointer initially points to the first element of the array. Use the following syntax: $currentElement=current($array);2.key() function key() function returns the array internal pointer currently pointing to the element
How to use Java8 Time API
Apr 28, 2023 pm 12:25 PM
1. Overview As part of this article, let us start with some problems with the existing Date and CalendarAPI and explore how the new Java8Date and TimeAPI solve these problems. We will also take a look at the core classes in the Java8 time class library, such as LocalDate, LocalTime, LocalDateTime, ZonedDateTime, Period, Duration and their APIs. 2. The problem of thread safety of the old time API (before Java 8)-Date and Calendar classes are not thread-safe, making it difficult for developers to debug concurrency problems of these APIs and need to write additional code to deal with them.
What is the difference and usage between time and datetime in python
May 02, 2023 am 11:01 AM
1. Two ways to represent time in Python: timestamp: offset in seconds relative to 1970.1.100:00:00, unique time tuple struct_time: a total of 9 elements>tm_year: year 1-12> tm_mon: month 1-12>tm_mday: day 1-31>tm_hour: hour 0-23>tm_min: minute 0-59>tm_sec: second 0-59>tm_wday: week 0-6 (0 means Sunday)>tm_day: Day of the year 1-366>tm_isdst: whether it is daylight saving, the default is -1.ti
