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mysql如何生成不重復(fù)的隨機數(shù)

mysql的rand函數(shù)可以生成一個0到1之間的隨機數(shù)，進行一定的放大即可得到一個隨機數(shù)。再通過條件查詢來限制新隨機數(shù)沒有在表中出現(xiàn)過。如下所示：

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SELECT FLOOR(RAND() * 99999) AS random_numFROM numbers

WHERE "random_num" NOT IN (SELECT my_number FROM numbers)

LIMIT 1

MySQL產(chǎn)生隨機數(shù)

MYSQL 取隨機數(shù)

2010年04月26日 星期一 09:48

mysql 取隨機數(shù)

--對一個表取任意隨機數(shù)

SELECT *

FROM TMP_XF_TEST

WHERE ID = (SELECT FLOOR(RAND() * (SELECT MAX(ID) FROM TMP_XF_TEST)))

order by id LIMIT 1;

--有條件性的取隨機數(shù)

SELECT *

FROM TMP_XF_TEST

WHERE ID = (SELECT FLOOR(RAND() *

((SELECT MAX(ID) FROM TMP_XF_TEST WHERE GID = 9) -

(SELECT MIN(ID) FROM TMP_XF_TEST WHERE GID = 9))) +

(SELECT MIN(ID) FROM TMP_XF_TEST WHERE GID = 9))

AND GID = 9

ORDER BY ID LIMIT 1;

--gid上存在索引

或者

SELECT *

FROM TMP_XF_TEST AS t1 JOIN

(SELECT ROUND(RAND() * ((SELECT MAX(id) FROM TMP_XF_TEST WHERE GID = 9)-(SELECT MIN(id) FROM TMP_XF_TEST WHERE GID = 9))

+(SELECT MIN(id) FROM TMP_XF_TEST WHERE GID = 9)) AS id) AS t2

WHERE t1.id = t2.id AND t1.GID = 9

ORDER BY t1.id LIMIT 1;

#########

不要用下面的杯具寫法

mysql insert into tmp_xf_test(user_nick,gid,item_id,gmt_create,gmt_modified,memo)

- select user_nick,gid,item_id,gmt_create,gmt_modified,memo from tmp_xf_test;

Query OK, 165888 rows affected (9.65 sec)

Records: 165888 Duplicates: 0 Warnings: 0

mysql SELECT *

- FROM `tmp_xf_test`

- WHERE id = (SELECT FLOOR( MAX(id) * RAND()) FROM `tmp_xf_test` )

- ORDER BY id LIMIT 1;

+-----+-----------+-----+---------+---------------------+---------------------+--------------------+

| id | user_nick | gid | item_id | gmt_create | gmt_modified | memo |

+-----+-----------+-----+---------+---------------------+---------------------+--------------------+

| 467 | 玄風 | 9 | 123 | 2010-04-26 14:56:39 | 2010-04-26 14:56:39 | 玄風測試使用的數(shù)據(jù) |

+-----+-----------+-----+---------+---------------------+---------------------+--------------------+

1 row in set (51.12 sec)

mysql explain SELECT *

- FROM `tmp_xf_test`

- WHERE id = (SELECT FLOOR( MAX(id) * RAND()) FROM `tmp_xf_test` )

- ORDER BY id LIMIT 1\G

*************************** 1. row ***************************

id: 1

select_type: PRIMARY

table: tmp_xf_test

type: index

possible_keys: NULL

key: PRIMARY

key_len: 8

ref: NULL

rows: 1

Extra: Using where

*************************** 2. row ***************************

id: 2

select_type: UNCACHEABLE SUBQUERY

table: tmp_xf_test

type: index

possible_keys: NULL

key: idx_tmp_xf_test_gid

key_len: 4

ref: NULL

rows: 331954

Extra: Using index

2 rows in set (0.01 sec)

---

mysql SELECT * FROM `tmp_xf_test` t1 join

- (SELECT FLOOR( MAX(id) * RAND()) as id FROM `tmp_xf_test` ) as t2

- where t1.id =t2.id

- ORDER BY t1.id LIMIT 1;

+-------+-----------+-----+---------+---------------------+---------------------+--------------------+-------+

| id | user_nick | gid | item_id | gmt_create | gmt_modified | memo | id |

+-------+-----------+-----+---------+---------------------+---------------------+--------------------+-------+

| 40311 | 玄風 | 9 | 123 | 2010-04-28 15:47:19 | 2010-04-28 15:47:19 | 玄風測試使用的數(shù)據(jù) | 40311 |

+-------+-----------+-----+---------+---------------------+---------------------+--------------------+-------+

1 row in set (0.14 sec)

##############

mysql SELECT * FROM `tmp_xf_test`

- WHERE id = (SELECT floor(RAND() * (SELECT MAX(id) FROM `tmp_xf_test`)))

- ORDER BY id LIMIT 1;

+------+-----------+-----+---------+---------------------+---------------------+--------------------+

| id | user_nick | gid | item_id | gmt_create | gmt_modified | memo |

+------+-----------+-----+---------+---------------------+---------------------+--------------------+

| 1352 | 玄風 | 9 | 123 | 2010-04-28 15:47:19 | 2010-04-28 15:47:19 | 玄風測試使用的數(shù)據(jù) |

+------+-----------+-----+---------+---------------------+---------------------+--------------------+

1 row in set (0.00 sec)

mysql explain SELECT * FROM `tmp_xf_test`

- WHERE id = (SELECT floor(RAND() * (SELECT MAX(id) FROM `tmp_xf_test`)))

- ORDER BY id LIMIT 1\G

*************************** 1. row ***************************

id: 1

select_type: PRIMARY

table: tmp_xf_test

type: index

possible_keys: NULL

key: PRIMARY

key_len: 8

ref: NULL

rows: 1

Extra: Using where

*************************** 2. row ***************************

id: 3

select_type: SUBQUERY

table: NULL

type: NULL

possible_keys: NULL

key: NULL

key_len: NULL

ref: NULL

rows: NULL

Extra: Select tables optimized away

2 rows in set, 1 warning (0.00 sec)

對應(yīng)的另外一種杯具寫法是：

SELECT *

FROM TMP_XF_TEST

WHERE ID = (SELECT FLOOR(RAND() * (MAX(ID) - MIN(ID))) + MIN(ID) MID

FROM TMP_XF_TEST

WHERE GID = 9)

AND GID = 9 LIMIT 1;

請教一下，如何在mysql中插入一條指定位數(shù)的隨機的整數(shù)，而且不可以重復(fù)

隨機不能保證不重復(fù)，銀行卡號不是隨機生成，

隨機取過值后要自己判斷是否重復(fù)，重復(fù)了再取，再判斷，

如果要取的值的位數(shù)都一樣的話，告訴你個簡單的方法，

比如取3位隨機整數(shù)mt_rand(100,999);

不用循環(huán)著一位一位的取

MYSQL 獲取隨機數(shù)的問題?。。。。。。。。。。。。。?！

給你提供一個思路你看是否可行；

1.隨機數(shù)不用MYSQL生成，用程序（如PHP）生成，范圍在ID的最大和最小之間；

2.根據(jù)生成的隨機數(shù)去數(shù)據(jù)庫直接查詢，如果沒有就重復(fù)一次操作；

怎么從mysql表中隨機取數(shù)據(jù)

從mysql數(shù)據(jù)庫表中隨機獲取數(shù)據(jù)

其實，從數(shù)據(jù)庫隨機獲取數(shù)據(jù)，很簡單，只須用到一個rand()函數(shù);

select * from table_name order by rand() limit 0,5;

下面是一個小實例：

從文章表中隨機獲取5條數(shù)據(jù)。

$dblink=mysql_connect("localhost","root","123456");

mysql_query("set names utf8");

mysql_select_db("aixuexi");

$sql="select * from waxx_article order by rand() limit 0,5";

$rs=mysql_query($sql);

while($row=mysql_fetch_array($rs)){

$rows[]=$row;

}

if($rows){

foreach($rows as $v){

?

div style="width:350px;height:35px;line-height:35px;border:1px solid #ccc;"?php echo $v['title']; ?/div

?php

}

}else{

echo "暫無文章";

}

mysql怎么生成不重復(fù)的隨機數(shù)

MySql數(shù)據(jù)庫隨機函授Rand()可以產(chǎn)生0~1之間帶小數(shù)的隨機數(shù)，只要將括號中的參數(shù)留空，所產(chǎn)生的數(shù)是完全隨機的，出現(xiàn)重復(fù)的幾率不大，但是不可避免會有重復(fù)的可能，如果需要完全避免重復(fù)，可以先用隨機函數(shù)產(chǎn)生一堆數(shù)字，然后用剔除其中的重復(fù)數(shù)這個辦法來實現(xiàn)。

例如先用循環(huán)產(chǎn)生一批隨機數(shù)并存入數(shù)據(jù)表中，再用

select distinct colName from tableName;

選出無重復(fù)的隨機數(shù)予以應(yīng)用

分享題目：mysql怎么取隨機整數(shù),mysql 隨機取值
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