Mysql Round Function

In our development of the efficiency has been a problem, especially for a lot of large data operations, today we ran into a random query data, at first we may think of the simplest order by RAND () to operate but the efficiency is not flattering ah. Recently, because of the need to study the MySQL random extraction implementation method. For example, to randomly extract a record from the TableName table, the general wording is: SELECT * from TableName ORDER by RAND () LIM ...

Recently due to the need to study about MYSQL based random extraction method. For example, to randomly extract a record from the table table, we generally write: SELECT * FROM tablename ORDER BY RAND () LIMIT 1. However, I checked the official MYSQL manual, which prompts for RAND () probably means that the ORDER BY clause can not be used inside the RAND () function, because this will lead to multiple data columns were swept ...

This cost me a lot of time, the use of php, my head is mysql, it has been affected by a paging category, access is not supported limit page, like the same key, the problem solved immediately. Look at the comments should be very easy to understand, access to the paging sql from asp json google code up 001 <? Php 002 / ** 003 // paging class 004 * / 00 ...

Oh, the following code is a little messy ah, is what I do in the test, PHP mysql date calculation code [DATEDIFF] is also the day I need to try it. Here's a look at Code function A ($d) {$Date _1=date ("y-m-d"); $Date _2= $d;   $Date _list_a1=explode ("-", $Date _1); $Date _l ...

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