mysql结果变量中

DELIMITER //

CREATE PROCEDURE example_procedure()
BEGIN
    DECLARE result INT;
    SELECT COUNT(*) INTO result FROM your_table;
    SELECT result;
END //

DELIMITER ;

DELIMITER //

CREATE PROCEDURE example_procedure()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE v_id INT;
    DECLARE v_name VARCHAR(255);
    DECLARE cur CURSOR FOR SELECT id, name FROM your_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO v_id, v_name;
        IF done THEN
            LEAVE read_loop;
        END IF;
        -- 处理每一行数据
        SELECT v_id, v_name;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;

DELIMITER //

CREATE PROCEDURE example_procedure()
BEGIN
    DECLARE result VARCHAR(1000) DEFAULT '';
    DECLARE v_value VARCHAR(255);
    DECLARE done INT DEFAULT FALSE;
    DECLARE cur CURSOR FOR SELECT value FROM your_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO v_value;
        IF done THEN
            LEAVE read_loop;
        END IF;
        SET result = CONCAT(result, v_value, ',');
    END LOOP;

    CLOSE cur;

    -- 去掉最后一个逗号
    SET result = SUBSTRING(result, 1, LENGTH(result) - 1);
    SELECT result;
END //

DELIMITER ;