Question

我想返回一个在存储过程中动态创建的集合（为了简单起见，我们假设集合是在循环内计算的偶数列表。）

我使用过的某些数据库有一个SUSPEND操作，它将OUT参数的当前值添加到过程的结果集中，如下所示：

DELIMITER $

CREATE PROCEDURE EvenNumbers(
    IN n INT, OUT NUM INT )
BEGIN
    DECLARE i INT DEFAULT 0;
    WHILE i < n DO
        SET NUM = i;
        SUSPEND; /* adds a row with a value 'i' for column NUM to the result set */
        SET i = i+2;
    END WHILE;
END$

DELIMITER ;

SUSPEND是MySQL中的关键字，但我认为它不会做同样的事情，因为它不起作用（Error: Unexpected 'SUSPEND'）。

那么，如何从MySQL中的存储过程逐个返回一组行？

Answer 1

我知道你想要一个偶数发生器？这是纯MySQL而不使用存储过程。

首先，您需要使用下面的查询生成大量关闭数字。此查询生成1到10000条记录。

<强>查询

  SELECT 
    @row := @row + 1 AS ROW
  FROM  
  (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row1
  CROSS JOIN (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row2
  CROSS JOIN (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row3
    CROSS JOIN (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row4  

  CROSS JOIN (
    SELECT @row := 0
  ) init_user_param

主要查询。

<强>查询

SELECT
 *
FROM (

  SELECT 
    @row := @row + 1 AS ROW
  FROM  
  (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row1
  CROSS JOIN (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row2
  CROSS JOIN (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row3
    CROSS JOIN (
     SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
  ) row4  

  CROSS JOIN (
    SELECT @row := 0
  ) init_user_param

) 
 ROWS
WHERE
  ROWS.ROW BETWEEN 1 AND 10
 AND
  ROWS.ROW MOD 2 = 0

<强>结果

Answer 2

亚历克斯，您可以在存储过程中创建一个临时表（这是完全正常的），将计算结果存储在其中，并在完成计算后返回临时表的内容。因此，使用过程返回的正常结果集，而不是OUT参数。

Answer 3

我只是生成JSON并将其作为单个结果返回

Bellow是一个示例查询，尽管很大，但它从联结中清晰可见的不同表中提取内容，但仍返回JSON对象

    select
JSON_OBJECT(
'application_id',       yvs_job_search_application.application_id, 
'progress_id',          yvs_job_search_application.progress_id, 
 'progress_name',       yvs_job_search_application_progress.progress_name,
'type_id',                  yvs_job_search_application.type_id, 
'type_name',                yvs_job_search_application_type.type_name, 
'wage',                         yvs_job_search_application.wage, 
'wage_id',                  yvs_job_search_application.wage_id, 
'wage_name',                yvs_job_search_wage_type.wage_name, 
'position_name',            yvs_job_search_application.position_name, 
'agency_refference',    yvs_job_search_application.agency_refference, 
'position_location',    yvs_job_search_application.position_location, 
'job_description',      yvs_job_search_application.job_description, 
'agency_id',                yvs_job_search_application.agency_id, 
'agency_name',          yvs_job_search_agency.agency_name , 
'default_number',       yvs_job_search_agency.default_number, 
'agency_site',              yvs_job_search_agency.agency_site ,
'agent_id',                 yvs_job_search_application.agent_id, 
'agent_name',           yvs_job_search_agent.agent_name , 
'agent_email',          yvs_job_search_agent.agent_email, 
'agent_phone',          yvs_job_search_agent.agent_phone , 
'agent_mobile',             yvs_job_search_agent.agent_mobile  )

 from yvs_job_search_application 
 join yvs_job_search_application_progress on yvs_job_search_application.progress_id = yvs_job_search_application_progress.progress_id 
 join yvs_job_search_application_type onyvs_job_search_application.type_id = yvs_job_search_application_type.type_id  
 join yvs_job_search_wage_type on yvs_job_search_application.wage_id = yvs_job_search_wage_type.wage_id 
 join yvs_job_search_agency on yvs_job_search_application.agency_id = yvs_job_search_agency.agency_id 
 join yvs_job_search_agent on yvs_job_search_application.agent_id = yvs_job_search_agent.agent_id
 ;

您可以在mysql上阅读JSON函数 JSON Functions in MySQL

如何从MySQL存储过程一次返回多行

3 个答案: