Shulou(Shulou.com)05/31 Report--

This article shows you how to extract random data from the table in MySQL. The content is concise and easy to understand, which will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

How to extract random data from MySQL table

SELECT*FROMtable_nameORDERBYrand () LIMIT5

Here's what rand says in the manual:

RAND ()

RAND (N)

Returns in the range 0 to 1. The random floating point value within 0. If an integer parameter N is specified, it is used as the seed value.

Mysql > selectRAND ()

-> 0. 5925

Mysql > selectRAND (20)

-> 0. 1811

Mysql > selectRAND (20)

-> 0. 1811

Mysql > selectRAND ()

-> 0. 2079

Mysql > selectRAND ()

-> 0. 7888

How to extract random data from MySQL table

You cannot use a column with the RAND () value in an ORDERBY clause, because ORDERBY will repeat the column multiple times. However, in MySQL3. In 23, you can do: SELECT*FROMtable_nameORDERBYRAND (), which is good for getting one from SELECT*FROMtable1,table2WHEREa=bANDc

But I tried it. For a table with 8,000 records, it takes 0 for one execution. 08sec, . A little slow.

Later, I asked google and got the following code

SELECT*

FROMtable_nameASr1JOIN

(SELECTROUND (RAND ()) *

(SELECTMAX (id)

FROMtable_name)) ASid)

ASr2

WHEREr1 . Id > = R2. Id

ORDERBYr1 . IdASC

LIMIT5

Execution efficiency needs 0. 02sec . Unfortunately, there is only mysql4. one. * only the above sub-queries are supported.

The above is how to extract random data from the table in MySQL. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.