同一列上的不同值计数

您可以在COUNT函数中使用CASE或DECODE语句。

  SELECt item_category,         COUNT (*) total,         COUNT (DECODE (item_status, 'serviceable', 1)) AS serviceable,         COUNT (DECODE (item_status, 'under_repair', 1)) AS under_repair,         COUNT (DECODE (item_status, 'condemned', 1)) AS condemned    FROM mytableGROUP BY item_category;

输出：

ITEM_CATEGORY   TOTAL   SERVICEABLE UNDER_REPAIR    CONDEMNED----------------------------------------------------------------chair5       12    2table5       31    1