Question

我有一个包含以下列的联接表：

id_cat | category | risk_factor | rs | id_sample | R1 | R2 | rs

我希望生成一个像：

这样的表

category | total | high | medium | low

其中，总数，高，中，低是从计算得出的总和，该计算确定风险因素是否为＆＃39; risk_factor＆＃39;等于＆＃39; R1＆＃39;和/或＆＃39; R2＆＃39;对于那一行，

根据以下伪代码

SELECT
        category, 
        count(*) as total,
        sum(case when R1 = risk_factor and R2 = risk_factor) = 1 as high,
        sum(case when R1 = risk_factor or R2 = risk_factor) = 1 as med,
        sum(case when R1 <> risk_factor and R2 <> risk_factor) = 1 as low
        FROM mydatabase.mytable1 
         JOIN mydatabase.mytable2 as r
            ON mytable1.rs=r.rs
                WHERE id_sample = 'sample1' 
                GROUP BY category
                ORDER BY category ASC;

我的问题是如何在sum语句中正确语法case语句。

Answer 1

选择类别，

    COUNT(*) AS total,

    SUM(CASE WHEN R1 = risk_factor AND R2 = risk_factor THEN 1 ELSE 0 END ) AS high,

    SUM(CASE WHEN R1 = risk_factor OR R2 = risk_factor THEN 1 ELSE 0 END ) AS med,

    SUM(CASE WHEN R1 <> risk_factor AND R2 <> risk_factor THEN 1 ELSE 0 END ) AS low

    FROM mydatabase.mytable1 
     JOIN mydatabase.mytable2 AS r
        ON mytable1.rs=r.rs
            WHERE id_sample = 'sample1' 
            GROUP BY category
            ORDER BY category ASC;

mysql条件选择使用总和

1 个答案: