如何在mysql中遍历db表，并在列出现在不同行时显示该列。

-- 创建存储过程
DELIMITER //

CREATE PROCEDURE traverse_table()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE col_value VARCHAR(255);
    DECLARE cur CURSOR FOR SELECT DISTINCT column_name FROM your_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    -- 创建临时表用于存储结果
    CREATE TEMPORARY TABLE IF NOT EXISTS temp_table (column_name VARCHAR(255));

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO col_value;
        IF done THEN
            LEAVE read_loop;
        END IF;

        -- 判断列出现在不同行时显示该列
        SET @sql = CONCAT('SELECT COUNT(DISTINCT ', col_value, ') INTO @count FROM your_table');
        PREPARE stmt FROM @sql;
        EXECUTE stmt;
        DEALLOCATE PREPARE stmt;

        IF @count > 1 THEN
            INSERT INTO temp_table (column_name) VALUES (col_value);
        END IF;
    END LOOP;

    CLOSE cur;

    -- 查询结果
    SELECT * FROM temp_table;

    -- 删除临时表
    DROP TABLE IF EXISTS temp_table;
END //

DELIMITER ;

-- 调用存储过程
CALL traverse_table();