mysql如何選擇列的最大值作為結果集中的另一列

Question

我的桌子是這樣的

ID  VALUE  
1   4  
2   6  
3   12  

我想在mysql中以這種格式獲得輸出，你能為我提供相應的sql嗎？

ID   VALUE  MAX_VALUE DIV_BY_MAX_VALUE  
1       4     12         0.33  
2       6     12         0.5   
3      12     12         1.0

Answer 1

你會加入最大值並進行分工：

select t.*, x.maxvalue, t.value / x.maxvalue
from t cross join
     (select max(value) as maxvalue from t) x;

Answer 2

試試這個：

select id,value,(select max(value) from mytable) as max_value, value/(select max(value) from mytable) as division from mytable;

Answer 3

START TRANSACTION;
SET @max_value = (select max(value) from mytable);
Select id, value, @max_value, value/@max_value as div_by_max from mytable;
COMMIT;