對於mysql中每一列的閾值計數值

Question

mysql> show columns from MYTABLE; 
+-------+--------------+------+-----+---------+-------+ 
| Field | Type   | Null | Key | Default | Extra | 
+-------+--------------+------+-----+---------+-------+ 
| x  | int(11)  | NO | PRI | NULL |  | 
| y  | int(11)  | NO | PRI | NULL |  | 
| c0 | decimal(3,1) | NO |  | NULL |  | 
| c1 | decimal(3,1) | NO |  | NULL |  | 
| c2 | decimal(3,1) | NO |  | NULL |  | 
| c3 | decimal(3,1) | NO |  | NULL |  | 
| c4 | decimal(3,1) | NO |  | NULL |  | 
| c5 | decimal(3,1) | NO |  | NULL |  | 
| c6 | decimal(3,1) | NO |  | NULL |  | 
| c7 | decimal(3,1) | NO |  | NULL |  | 
| c8 | decimal(3,1) | NO |  | NULL |  | 
| c9 | decimal(3,1) | NO |  | NULL |  | 
+-------+--------------+------+-----+---------+-------+ 

我想爲以'c'開始的每列都超過特定閾值（比如說20.0）的值進行計數。

對單個列（如CO）我會做這樣的事情：

SELECT COUNT(*) FROM MYTABLE WHERE c0 > 20.0; 

但是，我該怎麼做了C1，C2，C3等一樣...在一個單一的查詢？

Answer 1

我認爲這會爲你工作：

SELECT SUM(IF(c0 > 20, 1, 0)) AS count_0, SUM(IF(c1 > 20, 1, 0)) AS count_1 
FROM table