drop PROCEDURE if EXISTS test12;
-- 使用drop 來刪除儲存過程或者表

create PROCEDURE test12()
-- 建立儲存過程 命名為test12 

BEGIN

  set @tableNames = CONCAT('background');
  -- '@' 先在使用者變數中儲存值然後在以後引用它

  set @beanId = 6;

  set @sqlStr = CONCAT('select * from ' ,@tableNames ,
   ' where background_id = ?' );
   
 
-- 拼接查詢總記錄的SQL語句 

  prepare stmt from @sqlStr;
   -- 預定義一個語句，並將它賦給 stmt

  execute stmt using @beanId;
   -- 執行語句

  deallocate prepare stmt;
  -- 要釋放一個預定義語句的資源
END;

call test12(); -- 儲存過程的執行測試 

CREATE DEFINER=`root`@`%` PROCEDURE `loop3`(table_name1 varchar(44),table_name2 varchar(44))
BEGIN
 

    #Routine body goes here...
    set @tableName1=concat(table_name1);
    set @tableName2=concat(table_name2);
    
    set @sqlStr=concat('select * from ',@tableName1,' limit 5');
    prepare stmt from @sqlStr;
    execute stmt;
--     deallocate prepare stmt;
    
    set @sqlStr_=concat('select * from 
 
',@tableName2,' limit 5');
    prepare stmt from @sqlStr_;
    execute stmt;
    deallocate prepare stmt;
    
END

create PROCEDURE tests(tableName varchar(20)) 
-- 建立儲存過程 命名為tests

BEGIN   -- 儲存過程的開始

  set @tableNames = CONCAT(tableName); 
  -- @先在使用者變數中儲存值然後在以後引用它

  set @sqlStr = CONCAT('select * from ', @tableNames);
  -- 拼接查詢總記錄的SQL語句 

  prepare stmt from @sqlStr; -- 預定義一個語句，並將它賦給 stmt

  execute stmt ; -- 執行語句

  deallocate prepare stmt;-- 要釋放一個預定義語句的資源

END;  -- 儲存過程的結束