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mysql双游标嵌套循环方式

作者：tonglei111

这篇文章主要介绍了mysql双游标嵌套循环方式，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教

mysql双游标嵌套循环

系统要上线新功能，引入了BPMN流程引擎，引入该引擎后就会涉及到历史数据处理问题，因为系统已经生成了上千条业务数据，由于不是靠BPMN引擎流转的，所以需要将业务数据和流程引擎关联起来，有多少条在执行的业务数据，就生成多少条流程实例，我们的流程引擎使用的是activiti流程引擎框架；

其中一块的历史数据处理是要查询出符合条件的历史数据，然后遍历循环业务，业务数据中有个处理人的字段是多人的，要把这个多人的以逗号分隔开，有几人再次循环几次；

废话不多说，直接上代码：

delimiter //
drop procedure if exists procedure_test;
create procedure procedure_test()
begin
    declare count_ int default 0;
    declare requirementCount_ int default 1;
    declare assigineeCount_ int default 1;
    declare result_ int default 0;
    declare startUserId_ int ;
    declare runTaskAssignee int ;
    declare businessMainDataId int;
    declare businessCode varchar(10);
    declare users varchar(250);
    declare process_serial_number int default 0;
    -- 创建游标1
    declare cursor_test1 cursor for select o.commituserId,o.id,o.code from rp_original_requirement o where o.status = 1 and o.currentNode = 16;
    -- 创建游标2 ,这个游标的创建使用了：将数据库内某个字段以逗号分隔的列，拆成一个数据列表，这样游标2就可以遍历执行这个数据集了
    -- 其中语句：select (id-1) as id from rp_nonstandard_approve c order by id asc limit 21  是要查出一个从0开始的递增的连续数字，rp_nonstandard_approve 的主键id刚好是自增的主键，limit 21 是因为a.approveHandlers字段最多存20个人，所以这里要大于20；
    declare cursor_test2 cursor for select substring_index(substring_index(a.approveHandlers,',',d.id+1),',',-1) as assignee from rp_nonstandard_approve a join ( select (id-1) as id from rp_nonstandard_approve c order by id asc limit 21 ) d on d.id<(length(a.approveHandlers)-length(replace(a.approveHandlers,',',''))+1) where a.status = 1 and a.requirementID=businessMainDataId ;
    -- 游标循环结束
    declare exit handler for not found close cursor_test1 ;
    select count(1) into requirementCount_  from  rp_original_requirement o where o.status = 1 and o.currentNode = 16;
    select p.id_ into @procDefId from act_re_prodef p left join act_re_deployment ard on p.deployment_id_= ard.id_
    where p.key_='nonstandardProcess' order by deploy_time_ desc limit 1;
    set @i=1;
    -- 开启游标，调用开启游标时才会执行对应游标的查询方法
    open cursor_test1 ;
    while @i<=requirementCount_  do
        -- 将游标中的值赋值给申明的变量，顺序要和游标定义内的一致；
        fetch cursor_test1 into startUserId_ ,businessMainDataId ,businessCode ;
        set process_serial_number = process_serial_number + 1;
        set @processInstanceName = concat('NSP',date_formart(now(),'%Y%m%d%H%i%s'),lpad(process_serial_number,6,0));
        set @mainProcessId=repalce(uuid(),'-','');
        set @startUserId= startUserId_ ;
        -- 运行时实例
        insert into act_ru_execution (id_, rev_, proc_inst_id_, business_key_, parent_id_, proc_def_id_, super_exec_, root_proc_inst_id_, act_id_, is_active_, is_concurrent_, is_scope_, is_event_scope_, is_mi_root_, suspension_state_, cached_ent_state_, tenant_id_, name_, start_time_, start_user_id_, lock_time_, is_count_enable_, evt_subscr_count_, task_count_, job_count_, timer_job_count_, susp_job_count_, deadletter_job_count_, var_count_, id_link_count_ )
        values (@mainProcessId,1,@mainProcessId,null,null,@procDefId,null,@mainProcessId,null,1,0,1,0,0,1,null,'',@processInstanceName ,sysdate(),@startUserId,null,0,0,0,0,0,0,0,0,0);
    set @middleProcessId = replace(uuid(),'-','');
    set @middleProcessActKey = 'nonStandardApprove';
    insert into act_ru_execution (id_, rev_, proc_inst_id_, business_key_, parent_id_, proc_def_id_, super_exec_, root_proc_inst_id_, act_id_, is_active_, is_concurrent_, is_scope_, is_event_scope_, is_mi_root_, suspension_state_, cached_ent_state_, tenant_id_, name_, start_time_, start_user_id_, lock_time_, is_count_enable_, evt_subscr_count_, task_count_, job_count_, timer_job_count_, susp_job_count_, deadletter_job_count_, var_count_, id_link_count_ )
        values (@middleProcessId,1,@mainProcessId,null,@mainProcessId,@procDefId,null,@mainProcessId,@middleProcessActKey,0,0,0,0,1,1,null,'',null ,sysdate(),null,null,0,0,0,0,0,0,0,0,0);
    -- 当前非标审批环节的处理人数
    select count(1) into assigineeCount_  from (select substring_index(substring_index(a.approveHandlers,',',d.id+1),',',-1) as assignee from rp_nonstandard_approve a join ( select (id-1) as id from rp_nonstandard_approve c order by id asc limit 21 ) d on d.id<(length(a.approveHandlers)-length(replace(a.approveHandlers,',',''))+1) where a.status = 1 and a.requirementID=businessMainDataId ) g;
    select h.approve_handlers into users from rp_nonstandard_approve  h where h.status = 1 and h.requirementID=businessMainDataId;
    -- 中间运行时变量
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','nrOfActiveInstances',@middleProcessId,@mainProcessId,null,null,null,assigineeCount_  ,assigineeCount_  ,null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','nrOfCompletedInstances',@middleProcessId,@mainProcessId,null,null,null,0,0,null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','nrOfInstances',@middleProcessId,@mainProcessId,null,null,null,assigineeCount_  ,assigineeCount_  ,null) ;
    -- 主运行是变量
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'long','requirementId',@mainProcessId,@mainProcessId,null,null,null,businessMainDataId,businessMainDataId,null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'json','users',@mainProcessId,@mainProcessId,null,null,null,null,concat('[',users,']'),null) ;
    -- 历史实例
    set @startActId = 'newRequirement';
    insert into act_hi_procinst (id_, proc_inst_id_, business_key_, proc_def_id_, start_time_, end_time_, duration_, start_user_id_, start_act_id_, end_act_id_, super_process_instance_id_, delete_reason_,tenant_id_, name_) values(@mainProcessId,@mainProcessId,null,@procDefId,sysdate(),null,null,@startUserId,@startActId,null,null,null,'',@processInstanceName);
    open cursor_test2 ;
    set @j= 1;
    while @j<=assigineeCount_  do
        fetch cursor_test2  into runTaskAssignee ;
        -- 根据非标处理人数循环插入执行数据
        set @taskProcessId = replace(uuid(),'-','');
        insert into act_ru_execution (id_, rev_, proc_inst_id_, business_key_, parent_id_, proc_def_id_, super_exec_, root_proc_inst_id_, act_id_, is_active_, is_concurrent_, is_scope_, is_event_scope_, is_mi_root_, suspension_state_, cached_ent_state_, tenant_id_, name_, start_time_, start_user_id_, lock_time_, is_count_enable_, evt_subscr_count_, task_count_, job_count_, timer_job_count_, susp_job_count_, deadletter_job_count_, var_count_, id_link_count_ )
        values (@taskProcessId,1,@mainProcessId,null,@middleProcessId,@procDefId,null,@mainProcessId,@middleProcessActKey,1,0,0,0,0,1,null,'',null ,sysdate(),null,null,0,0,0,0,0,0,0,0,0);
    -- 根据非标处理人数循环插入任务数据
    -- 任务数据
    set @runTaskId = replace(uuid(),'-','');
    set @runTaskKey= 'nonStandardApprove';
    set @runTaskName= '审批';
    set @runTaskAssignee = runTaskAssignee;
    insert into act_ru_task (id_,rev_,execution_id_,proc_inst_id_,proc_def_id_,name_,parent_task_id_,description_,task_def_key_,owner_,assignee_,delegation_,priority_,create_time_,due_date_category_,suspension_state_,tenant_id_,form_key_,claim_time_) values (@runTaskId,1,@taskProcessId,@mainProcessId,@procDefId,@runTaskName,NULL,NULL,@runTaskKey,NULL,@runTaskAssignee,NULL,50,sysdate(),null,null,1,'',null,null);
    -- 根据非标处理人数循环插入任务 
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'string','user',@taskProcessId,@mainProcessId,null,null,null,null,@runTaskAssignee,null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','loopCounter',@taskProcessId,@mainProcessId,null,null,null,0,'0',null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'string','user',@taskProcessId,@mainProcessId,@runTaskId ,null,null,null,@runTaskAssignee,null) ;    
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','loopCounter',@taskProcessId,@mainProcessId,@runTaskId,null,null,0,'0',null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','nrOfActiveInstances',@taskProcessId,@mainProcessId,@runTaskId,null,null,assigineeCount_  ,assigineeCount_  ,null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','nrOfCompletedInstances',@taskProcessId,@mainProcessId,@runTaskId,null,null,0,'0',null) ;
    insert into act_ru_variable (id_, rev_, type_, name_, execution_id_, proc_inst_id_, task_id_, bytearray_id_, double_, long_, text_, text2_) values (replace(uuid(),'-',''),1,'interger','nrOfInstances',@taskProcessId,@mainProcessId,@runTaskId,null,null,assigineeCount_  ,assigineeCount_  ,null) ;
set @j=@j+1;
end while;
close cursor_test2 ;
set @businessMainDataId = businessMainDataId;
set @businessMainDataTable = 't_original_requirement';
set @businessCode = businessCode ;
insert into rp_pe_business_instance (business_main_data_id,business_main_data_table_name,process_instance_id,version,status,create_by,create_time,update_by,update_by,update_time,is_business_running_process,business_code) values(@businessMainDataId,@businessMainDataTable,@mainProcessId,replace(uuid(),'-',''),1,null,sysdate(),null,sysdate(),1,@businessCode);
set @i=@i+1;
set result_ =result_ +1;
end while;
close cursor_test1 ;
 select concat('数据处理条数：',result_ ) as resultdata;
end;

注意事项：

游标的脚本是在调用open时才会执行，比如我的游标cursor_test2 中有用到businessMainDataId 变量，但是在声明游标时这个变量是没有值的，fetch cursor_test1 into startUserId_ ,businessMainDataId ,businessCode 方法执行时才会把这个变量赋值，之后再执行open cursor_test2 时，businessMainDataId 已经有了值，这时就是根据此时的businessMainDataId 查询的审批数据；

mysql游标与嵌套循环

游标嵌套遍历

user表：

在这里插入图片描述

CREATE DEFINER=`root`@`localhost` PROCEDURE `test`()
BEGIN
    DECLARE user1 VARCHAR(100);
    DECLARE user2 VARCHAR(100);
    DECLARE done INT DEFAULT 0;
    DECLARE cursor_user1 CURSOR FOR(SELECT `name` FROM `user`); -- 定于游标1
    DECLARE cursor_user2 CURSOR FOR(SELECT `name` FROM `user`); -- 定义游标2
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; -- 结束标识
    OPEN cursor_user1; -- 开启游标1
    loop_1: LOOP -- 外层循环
    -- -------------------------------------------------------------------------------------
			# 尝试从游标1指向的数据集合获取数据，如果集合已经遍历完毕，done的值被设置为1。
			FETCH cursor_user1 INTO user1;
			IF done = 1 THEN LEAVE loop_1; END IF; -- 外层循环结束条件
			OPEN cursor_user2; -- 开启游标2
			loop_2: LOOP -- 内层循环
			-- -----------------------------------------------------------------------------
					# 尝试从游标2指向的数据集合获取数据，如果集合已经遍历完毕，done的值被设置为1。
					FETCH cursor_user2 INTO user2;
					IF done = 1 THEN LEAVE loop_2; END IF; -- 内层循环结束条件
					# do something...
		    -- -----------------------------------------------------------------------------
			END LOOP loop_2;
			CLOSE cursor_user2; -- 关闭游标2
			SET done = 0; -- important
    -- ------------------------------------------------------------------------------------
    END LOOP loop_1;
    CLOSE cursor_user1; -- 关闭游标1
END

测试

user表数据：

在这里插入图片描述

CREATE DEFINER=`root`@`localhost` PROCEDURE `test`()
BEGIN
    DECLARE result VARCHAR(2000) DEFAULT 'result';
    DECLARE user1 VARCHAR(100);
    DECLARE user2 VARCHAR(100);
    DECLARE done INT DEFAULT 0;
    DECLARE cursor_user1 CURSOR FOR(SELECT `name` FROM `user`); -- 定于游标1
    DECLARE cursor_user2 CURSOR FOR(SELECT `name` FROM `user`); -- 定义游标2
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; -- 结束标识
    OPEN cursor_user1; -- 开启游标1
    loop_1: LOOP -- 外层循环
    -- -------------------------------------------------------------------------------------
			# 尝试从游标1指向的数据集合获取数据，如果集合已经遍历完毕，done的值被设置为1。
			FETCH cursor_user1 INTO user1;
			IF done = 1 THEN LEAVE loop_1; END IF; -- 外层循环结束条件
			OPEN cursor_user2; -- 开启游标2
			loop_2: LOOP -- 内层循环
			-- -----------------------------------------------------------------------------
					# 尝试从游标2指向的数据集合获取数据，如果集合已经遍历完毕，done的值被设置为1。
					FETCH cursor_user2 INTO user2;
					IF done = 1 THEN LEAVE loop_2; END IF; -- 内层循环结束条件
					# do something...
					SET result = CONCAT(result,';',user1,'-',user2);
		    -- -----------------------------------------------------------------------------
			END LOOP loop_2;
			CLOSE cursor_user2; -- 关闭游标2
			SET done = 0; -- important
    -- ------------------------------------------------------------------------------------
    END LOOP loop_1;
    CLOSE cursor_user1; -- 关闭游标1
	SELECT result; 
END

执行结果：

在这里插入图片描述

总结

以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。

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