MySql中根據一列狀態值查詢狀態的個數

需求：

最近搞報表的項目，要寫數據庫sql語句，根據狀態值查詢狀態的個數，這個開始難為到我了，不過已經有解決辦法了。

在數據庫表中有一個字段是狀態(zt),這里面有1-7這7個狀態，現在查詢每個狀態的數量，並且顯示在一張表中。

正常情況下查狀態是：

SELECT COUNT(*) draft  FROM `it_project_info` WHERE `it_project_info`.item_status`='1';

SELECT COUNT(*) checks FROM `it_project_info` WHERE `it_project_info`.item_status`='2';

SELECT COUNT(*) plan FROM `it_project_info` WHERE `it_project_info`.item_status`='3';

SELECT COUNT(*) implement  FROM `it_project_info` WHERE `it_project_info`.item_status`='4';

SELECT COUNT(*) online  FROM `it_project_info` WHERE `it_project_info`.item_status`='5';

SELECT COUNT(*) cancel  FROM `it_project_info` WHERE `it_project_info`.item_status`='6';

SELECT COUNT(*) knot  FROM `it_project_info` WHERE `it_project_info`.item_status`='7';

首先，要先將行變成列：

SELECT t.*,
　　CASE WHEN t.`item_status`=1 THEN 1 ELSE 0 END AS draft,
　　CASE WHEN t.`item_status`=2 THEN 1 ELSE 0 END AS checks,
　　CASE WHEN t.`item_status`=3 THEN 1 ELSE 0 END AS plan,
　　CASE WHEN t.`item_status`=4 THEN 1 ELSE 0 END AS implement,
　　CASE WHEN t.`item_status`=5 THEN 1 ELSE 0 END AS online,
　　CASE WHEN t.`item_status`=6 THEN 1 ELSE 0 END AS cancel,
　　CASE WHEN t.`item_status`=7 THEN 1 ELSE 0 END AS knot
FROM `it_project_info` t

然后查詢每一列的個數：

SELECT 
　　IFNULL(SUM(m.draft), 0) draftTotal,
　　IFNULL(SUM(m.checks), 0) checkTotal,
　　IFNULL(SUM(m.plan), 0) planTotal,
　　IFNULL(SUM(m.implement), 0) implementTotal,
　　IFNULL(SUM(m.online), 0) onlineTotal,
　　IFNULL(SUM(m.cancel), 0) cancelTotal,
　　IFNULL(SUM(m.knot), 0) knotTotal
FROM
(
SELECT 
　　CASE WHEN t.`item_status`=1 THEN 1 ELSE 0 END AS draft,
　　CASE WHEN t.`item_status`=2 THEN 1 ELSE 0 END AS checks,
　　CASE WHEN t.`item_status`=3 THEN 1 ELSE 0 END AS plan,
　　CASE WHEN t.`item_status`=4 THEN 1 ELSE 0 END AS implement,
　　CASE WHEN t.`item_status`=5 THEN 1 ELSE 0 END AS online,
　　CASE WHEN t.`item_status`=6 THEN 1 ELSE 0 END AS cancel,
　　CASE WHEN t.`item_status`=7 THEN 1 ELSE 0 END AS knot
FROM `it_project_info` t
) m

這樣就可以得到想要的結果了。