Dynamic sql in Mysql

Mysql中的Dynamic sql，相似於oracle中的Execute immediately語法，寫法上稍微麻煩一點，下面是一個具體的例子。

DROP PROCEDURE IF EXISTS total_num;

CREATE PROCEDURE total_num(
IN p_begin INT,
IN p_end INT
)  
BEGIN  
    DECLARE v_begin INT DEFAULT 0;
    DECLARE v_end INT DEFAULT 0;
    DECLARE v_total INT DEFAULT 0;
    
    SET v_begin = p_begin;
    SET v_end = p_end;
    
    WHILE v_begin<=v_end DO 
      SET @sql = CONCAT('SELECT COUNT(1) INTO @item_count FROM t', v_begin);

      PREPARE stmt FROM @sql;
      EXECUTE stmt;
      SET v_total = v_total + @item_count;

      SET v_begin = v_begin+1;
    END WHILE;
    DEALLOCATE PREPARE stmt;

    SELECT v_total;
END

調用方式：

call total_num(1,2)