思路：先隨機排序然后再分組就好了。

1、創建表：

CREATE TABLE `xdx_test` ( `id` int(11) NOT NULL, `name` varchar(255) DEFAULT NULL, `class` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

2、插入數據

INSERT INTO xdx_test VALUES (1, ’張三-1’,’1’);INSERT INTO xdx_test VALUES (2, ’李四-1’,’1’);INSERT INTO xdx_test VALUES (3, ’王五-1’,’1’);INSERT INTO xdx_test VALUES (4, ’張三-2’,’2’);INSERT INTO xdx_test VALUES (5, ’李四-2’,’2’);INSERT INTO xdx_test VALUES (6, ’王五-2’,’2’);INSERT INTO xdx_test VALUES (7, ’張三-3’,’3’);INSERT INTO xdx_test VALUES (8, ’李四-3’,’3’);INSERT INTO xdx_test VALUES (9, ’王五-3’,’3’);

3、查詢語句

SELECT * FROM (SELECT * FROM xdx_test ORDER BY RAND()) aGROUP BY a.class

4、查詢結果

3 王五-1 1

5 李四-2 2

9 王五-3 3

3 王五-1 1

4 張三-2 2

7 張三-3 3

2 李四-1 1

5 李四-2 2

8 李四-3 3

補充知識：mysql實現隨機獲取幾條數據的方法（效率和離散型比較）

sql語句有幾種寫法、效率、以及離散型 比較

1：SELECT * FROM tablename ORDER BY RAND() LIMIT 想要獲取的數據條數；

2：SELECT *FROM `table` WHERE id >= (SELECT FLOOR( MAX(id) * RAND()) FROM `table` ) ORDER BY id LIMIT 想要獲取的數據條數;

3：SELECT * FROM `table` AS t1 JOIN (SELECT ROUND(RAND() * (SELECT MAX(id) FROM `table`)) AS id) AS t2 WHERE t1.id >= t2.id

ORDER BY t1.id ASC LIMIT 想要獲取的數據條數;

4：SELECT * FROM `table`WHERE id >= (SELECT floor(RAND() * (SELECT MAX(id) FROM `table`))) ORDER BY id LIMIT 想要獲取的數據條數;

5：SELECT * FROM `table` WHERE id >= (SELECT floor( RAND() * ((SELECT MAX(id) FROM `table`)-(SELECT MIN(id) FROM `table`)) + (SELECT MIN(id) FROM `table`))) ORDER BY id LIMIT 想要獲取的數據條數;

6：SELECT * FROM `table` AS t1 JOIN (SELECT ROUND(RAND() * ((SELECT MAX(id) FROM `table`)-(SELECT MIN(id) FROM `table`))+(SELECT MIN(id) FROM `table`)) AS id) AS t2 WHERE t1.id >= t2.id ORDER BY t1.id LIMIT 想要獲取的數據條數;

1的查詢時間>>2的查詢時間>>5的查詢時間>6的查詢時間>4的查詢時間>3的查詢時間，也就是3的效率最高。

以上6種只是單純的從效率上做了比較；

上面的6種隨機數抽取可分為2類：

第一個的離散型比較高，但是效率低；其他5個都效率比較高，但是存在離散性不高的問題；

怎么解決效率和離散型都滿足條件啦？

我們有一個思路就是： 寫一個存儲過程；

select * FROM test t1 JOIN (SELECT ROUND(RAND() * ((SELECT MAX(id) FROM test)-(SELECT MIN(id) FROM test)) + (SELECT MIN(id) FROM test)) AS id) t2 where t1.id >= t2.id limit 1

每次取出一條，然后循環寫入一張臨時表中；最后返回 select 臨時表就OK；

這樣既滿足了效率又解決了離散型的問題；可以兼并二者的優點；

下面是具體存儲過程的偽代碼

DROP PROCEDURE IF EXISTS `evaluate_Check_procedure`;DELIMITER ;;CREATE DEFINER=`root`@`%` PROCEDURE `evaluate_Check_procedure`(IN startTime datetime, IN endTime datetime,IN checkNum INT,IN evaInterface VARCHAR(36))BEGIN

-- 新建一張臨時表 ,存放隨機取出的數據

create temporary table if not exists xdr_authen_tmp ( `ID` bigint(20) NOT NULL AUTO_INCREMENT COMMENT ’序號’, `LENGTH` int(5) DEFAULT NULL COMMENT ’字節數’, `INTERFACE` int(3) NOT NULL COMMENT ’接口’, `XDR_ID` varchar(32) NOT NULL COMMENT ’XDR ID’, `MSISDN` varchar(32) DEFAULT NULL COMMENT ’用戶號碼’, `PROCEDURE_START_TIME` datetime NOT NULL DEFAULT ’0000-00-00 00:00:00’ COMMENT ’開始時間’, `PROCEDURE_END_TIME` datetime DEFAULT NULL COMMENT ’結束時間’, `SOURCE_NE_IP` varchar(39) DEFAULT NULL COMMENT ’源網元IP’, `SOURCE_NE_PORT` int(5) DEFAULT NULL COMMENT ’源網元端口’, `DESTINATION_NE_IP` varchar(39) DEFAULT NULL COMMENT ’目的網元IP’, `DESTINATION_NE_PORT` int(5) DEFAULT NULL COMMENT ’目的網元端口’, `INSERT_DATE` datetime DEFAULT NULL COMMENT ’插入時間’, `EXTEND1` varchar(50) DEFAULT NULL COMMENT ’擴展1’, `EXTEND2` varchar(50) DEFAULT NULL COMMENT ’擴展2’, `EXTEND3` varchar(50) DEFAULT NULL COMMENT ’擴展3’, `EXTEND4` varchar(50) DEFAULT NULL COMMENT ’擴展4’, `EXTEND5` varchar(50) DEFAULT NULL COMMENT ’擴展5’, PRIMARY KEY (`ID`,`PROCEDURE_START_TIME`), KEY `index_procedure_start_time` (`PROCEDURE_START_TIME`), KEY `index_source_dest_ip` (`SOURCE_NE_IP`,`DESTINATION_NE_IP`), KEY `index_xdr_id` (`XDR_ID`) ) ENGINE = InnoDB DEFAULT CHARSET=utf8;BEGINDECLARE j INT;DECLARE i INT;DECLARE CONTINUE HANDLER FOR NOT FOUND SET i = 1;

-- 這里的checkNum是需要隨機獲取的數據數，比如隨機獲取10條，那這里就是10，通過while循環來逐個獲取單個隨機記錄；

SET j = 0;WHILE j < checkNum DO set @sqlexi = concat( ’ SELECT t1.ID,t1.LENGTH,t1.LOCAL_PROVINCE,t1.LOCAL_CITY,t1.OWNER_PROVINCE,t1.OWNER_CITY,t1.ROAMING_TYPE,t1.INTERFACE,t1.XDR_ID,t1.RAT,t1.IMSI,t1.IMEI,t1.MSISDN,t1.PROCEDURE_START_TIME,t1.PROCEDURE_END_TIME,t1.TRANSACTION_TYPE,t1.TRANSACTION_STATUS,t1.SOURCE_NE_IP,t1.SOURCE_NE_PORT,t1.DESTINATION_NE_IP,t1.DESTINATION_NE_PORT,t1.RESULT_CODE,t1.EXPERIMENTAL_RESULT_CODE,t1.ORIGIN_REALM,t1.DESTINATION_REALM,t1.ORIGIN_HOST,t1.DESTINATION_HOST,t1.INSERT_DATE’, ’ into @ID,@LENGTH,@LOCAL_PROVINCE,@LOCAL_CITY,@OWNER_PROVINCE,@OWNER_CITY,@ROAMING_TYPE,@INTERFACE,@XDR_ID,@RAT,@IMSI,@IMEI,@MSISDN,@PROCEDURE_START_TIME,@PROCEDURE_END_TIME,@TRANSACTION_TYPE,@TRANSACTION_STATUS,@SOURCE_NE_IP,@SOURCE_NE_PORT,@DESTINATION_NE_IP,@DESTINATION_NE_PORT,@RESULT_CODE,@EXPERIMENTAL_RESULT_CODE,@ORIGIN_REALM,@DESTINATION_REALM,@ORIGIN_HOST,@DESTINATION_HOST,@INSERT_DATE ’, ’ FROM xdr_authen t1 JOIN (SELECT ROUND(RAND() * ((SELECT MAX(id) FROM xdr_authen)-(SELECT MIN(id) FROM xdr_authen)) + (SELECT MIN(id) FROM xdr_authen)) AS id) t2’, ’ WHERE t1.PROCEDURE_START_TIME >= '’,startTime,’'’, ’ AND t1.PROCEDURE_START_TIME < '’,endTime,’'’,’ AND t1.INTERFACE IN (’,evaInterface,’)’, ’ and t1.id >= t2.id limit 1’); PREPARE sqlexi FROM @sqlexi; EXECUTE sqlexi; DEALLOCATE PREPARE sqlexi;

-- 這里獲取的記錄有可能會重復，如果是重復數據，我們則不往臨時表中插入此條數據，再進行下一次隨機數據的獲取。依次類推，直到隨機數據取夠為止；

select count(1) into @num from xdr_authen_tmp where id = @ID; if @num > 0 or i=1 then SET j = j; ELSE insert into xdr_authen_tmp(ID,LENGTH,LOCAL_PROVINCE,LOCAL_CITY,OWNER_PROVINCE,OWNER_CITY,ROAMING_TYPE,INTERFACE,XDR_ID,RAT,IMSI,IMEI,MSISDN,PROCEDURE_START_TIME,PROCEDURE_END_TIME,TRANSACTION_TYPE,TRANSACTION_STATUS,SOURCE_NE_IP,SOURCE_NE_PORT,DESTINATION_NE_IP,DESTINATION_NE_PORT,RESULT_CODE,EXPERIMENTAL_RESULT_CODE,ORIGIN_REALM,DESTINATION_REALM,ORIGIN_HOST,DESTINATION_HOST,INSERT_DATE) VALUES(@ID,@LENGTH,@LOCAL_PROVINCE,@LOCAL_CITY,@OWNER_PROVINCE,@OWNER_CITY,@ROAMING_TYPE,@INTERFACE,@XDR_ID,@RAT,@IMSI,@IMEI,@MSISDN,@PROCEDURE_START_TIME,@PROCEDURE_END_TIME,@TRANSACTION_TYPE,@TRANSACTION_STATUS,@SOURCE_NE_IP,@SOURCE_NE_PORT,@DESTINATION_NE_IP,@DESTINATION_NE_PORT,@RESULT_CODE,@EXPERIMENTAL_RESULT_CODE,@ORIGIN_REALM,@DESTINATION_REALM,@ORIGIN_HOST,@DESTINATION_HOST,@INSERT_DATE); SET j = j + 1; end if; SET i=0;END WHILE;

-- 最后我們將所有的隨機數查詢出來，以結果集的形式返回給后臺

select ID,LENGTH,LOCAL_PROVINCE,LOCAL_CITY,OWNER_PROVINCE,OWNER_CITY,ROAMING_TYPE,INTERFACE,XDR_ID,RAT,IMSI,IMEI,MSISDN,PROCEDURE_START_TIME,PROCEDURE_END_TIME,TRANSACTION_TYPE,TRANSACTION_STATUS,SOURCE_NE_IP,SOURCE_NE_PORT,DESTINATION_NE_IP,DESTINATION_NE_PORT,RESULT_CODE,EXPERIMENTAL_RESULT_CODE,ORIGIN_REALM,DESTINATION_REALM,ORIGIN_HOST,DESTINATION_HOST,INSERT_DATE from xdr_authen_tmp;END;truncate TABLE xdr_authen_tmp;END;;DELIMITER ;

以上這篇MySql分組后隨機獲取每組一條數據的操作就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持好吧啦網。