按類型分組數據並顯示

Question

我有一個名爲'product'的表，其中包含'created_at'日期和'type'，它是一個varchar。

基本上我想要的是每種產品的COUNT（*）產品的輸出，適用於所有產品類型。我知道「類型」只有5個不同的值，因此可以用我想象的查詢將其縮小一點。

例子：

我一直在玩這個周圍沒有成功，似乎無法總結我的腦海圍繞它。有任何想法嗎？

Answer 1

嘗試此查詢

SELECT 
SUM(CASE WHEN type = 'type1' THEN 1 ELSE 0 END) AS type1_count, 
SUM(CASE WHEN type = 'type2' THEN 1 ELSE 0 END) AS type2_count, 
SUM(CASE WHEN type = 'type3' THEN 1 ELSE 0 END) AS type3_count, 
SUM(CASE WHEN type = 'type4' THEN 1 ELSE 0 END) AS type4_count, 
created_at 
GROUP BY created_at 

，對特定日期

SELECT 
SUM(CASE WHEN type = 'type1' THEN 1 ELSE 0 END) AS type1_count, 
SUM(CASE WHEN type = 'type2' THEN 1 ELSE 0 END) AS type2_count, 
SUM(CASE WHEN type = 'type3' THEN 1 ELSE 0 END) AS type3_count, 
SUM(CASE WHEN type = 'type4' THEN 1 ELSE 0 END) AS type4_count, 
created_at 
WHERE created_at = '2015-12-21' 
GROUP BY created_at 

隨着日期格式

SELECT 
SUM(CASE WHEN type = 'type1' THEN 1 ELSE 0 END) AS type1_count, 
SUM(CASE WHEN type = 'type2' THEN 1 ELSE 0 END) AS type2_count, 
SUM(CASE WHEN type = 'type3' THEN 1 ELSE 0 END) AS type3_count, 
SUM(CASE WHEN type = 'type4' THEN 1 ELSE 0 END) AS type4_count, 
DATE_FORMAT(created_at,'%Y/%m/%d') AS created_date 
GROUP BY created_at 
HAVING created_date = '2015/12/21'