Question

I have three tables.
Project(Id), attribute(Id), project_attribute(Id, project_id, attribute_id).

I want to create records in project_attribute table by using all attributes from attribute table to each project from project table.

To create such records i am using following store procedure.

DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `proj_attr`()
BEGIN   
    DECLARE proj_done, attribute_done BOOLEAN DEFAULT FALSE;    
    declare attributeId int(11) default 0;
    declare  projectId int(11) default 0;
    DECLARE curProjects CURSOR FOR SELECT id FROM project order by id;  
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET proj_done = TRUE;

    OPEN curProjects;
    cur_project_loop: LOOP
    FETCH FROM curProjects INTO projectId;

        IF proj_done THEN
        CLOSE curProjects;
        LEAVE cur_project_loop;
        END IF;

        BLOCK2: BEGIN
        DECLARE curAttribute CURSOR FOR SELECT id FROM attribute order by id;
        DECLARE CONTINUE HANDLER FOR NOT FOUND SET attribute_done = TRUE;
        OPEN curAttribute; 
        cur_attribute_loop: LOOP
        FETCH FROM curAttribute INTO attributeId;   
            IF attribute_done THEN
            CLOSE curAttribute;
            LEAVE cur_attribute_loop;
            END IF; 
            insert into project_attribute_value(project_id, attribute_id)
                values(projectId, attributeId); 
        END LOOP cur_attribute_loop;
        END BLOCK2;
    END LOOP cur_project_loop;


    END$$

DELIMITER ;

But, this procedure is creating records only for 1 project in project_attribute table even though there are 50 projects in Project table. Expected record count is count(projectId)*count(attributeId).

Answer 1

Try this, this will surely solve your issue.

DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `proj_attr`()
BEGIN   
    DECLARE proj_done, attribute_done BOOLEAN DEFAULT FALSE;    
    declare attributeId int(11) default 0;
    declare  projectId int(11) default 0;
    DECLARE curProjects CURSOR FOR SELECT id FROM project order by id;  
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET proj_done = TRUE;

    OPEN curProjects;
    cur_project_loop: LOOP
    FETCH FROM curProjects INTO projectId;

        IF proj_done THEN
        CLOSE curProjects;
        LEAVE cur_project_loop;
        END IF;

        BLOCK2: BEGIN
        DECLARE curAttribute CURSOR FOR SELECT id FROM attribute order by id;
        DECLARE CONTINUE HANDLER FOR NOT FOUND SET attribute_done = TRUE;
        OPEN curAttribute; 
        cur_attribute_loop: LOOP
        FETCH FROM curAttribute INTO attributeId;   
            IF proj_done THEN
            set proj_done = false;
            CLOSE curAttribute;
            LEAVE cur_attribute_loop;
            END IF; 
            insert into project_attribute_value(project_id, attribute_id)
                values(projectId, attributeId); 
        END LOOP cur_attribute_loop;
        END BLOCK2;
    END LOOP cur_project_loop;


    END$$

DELIMITER ;