将准备好的mysql查询转换为简单的选择查询

Question

如何将下面的mysql准备好的语句转换为简单的查询

SET @var_name =  (SELECT settings_table FROM prayertime_table where id = 1);  
SET @s = concat('select device_name from ', @var_name) ; 
PREPARE stmt1 FROM @s; 
EXECUTE stmt1; 
DEALLOCATE PREPARE stmt1; 

Answer 1