MySQL SELECT CONCAT() 列输出中的意外值

Question

我有一个 CONCAT 函数设置如下（完整 SQL 在底部）：

concat('Disadvantaged (', sum(1), ')') as 'Focus Group'

我希望在查询分组时在方括号中加上“Disadvantaged”这个词，即 Disadvantaged (39)

但是，我得到的是：446973616476616e74616765642028333929

这是我的完整查询：

SELECT Subject,
    concat('Disadvantaged (', sum(1), ')') as 'Focus Group',
    Avg(G1.Pointscore) as 'Average Result',
    Avg(G2.Pointscore) as 'Average KS4 Target',
    Avg(G1.Pointscore - G2.Pointscore) as 'Average Residual',
    sum(1) as 'No. Students',
    /* Attainment totals */
    sum(case when G1.Pointscore >= 7 then 1 else 0 end) as 'No. A*-A',
    sum(case when G1.Pointscore >= 5 then 1 else 0 end) as 'No. A*-C',
    /* Attainment percentages */
    sum(case when G1.Pointscore >= 7 then 1 else 0 end) / sum(1) as 'A*-A',
    sum(case when G1.Pointscore >= 5 then 1 else 0 end) / sum(1) as 'A*-C',
    /* Progress totals */
    sum(case when G1.Pointscore - G2.Pointscore > 1 then 1 else 0 end) as 'No. Sig Above',
    sum(case when G1.Pointscore - G2.Pointscore = 1 then 1 else 0 end) as 'No. Above',
    sum(case when G1.Pointscore - G2.Pointscore = 0 then 1 else 0 end) as 'No. On',
    sum(case when G1.Pointscore - G2.Pointscore = -1 then 1 else 0 end) as 'No. Below',
    sum(case when G1.Pointscore - G2.Pointscore < -1 then 1 else 0 end) as 'No. Sig Below',
    /* Progress percentages */
    sum(case when G1.Pointscore - G2.Pointscore > 1 then 1 else 0 end) / sum(1) as  'Sig Above',
    sum(case when G1.Pointscore - G2.Pointscore = 1 then 1 else 0 end) / sum(1) as 'Above',
    sum(case when G1.Pointscore - G2.Pointscore = 0 then 1 else 0 end) / sum(1) as 'On', 
    sum(case when G1.Pointscore - G2.Pointscore = -1 then 1 else 0 end) / sum(1) as 'Below',
    sum(case when G1.Pointscore - G2.Pointscore < -1 then 1 else 0 end) / sum(1) as 'Sig Below'
FROM Students S
INNER JOIN Results R ON S.UPN = R.UPN
INNER JOIN Grades G1 ON Result = G1.Grade
INNER JOIN Grades G2 ON Target = G2.Grade
WHERE Disadvantaged = 'Y'
GROUP BY Subject

更新：我发现另一个 post 在这里提出并回答了这个问题：

Weird behaviour of SUM and CONCAT in MySql

Answer 1

我认为您不能将 SUM 函数放入 CONCAT 函数中，而且我在本地尝试时也遇到了乱码。一种解决方法是包装您当前的查询，然后仅在 CONCAT 中使用列，例如

SELECT t.Subject,
       CONCAT('Disadvantaged (', t.`No. Students`, ')') AS 'Focus Group',
       t.`Average Result`,
       t.`Average KS4 Target`,
       t.`Average Residual`,
       t`.No. Students`,
       ...
FROM
(
    SELECT Subject,
           AVG(G1.Pointscore) AS 'Average Result',
           AVG(G2.Pointscore) AS 'Average KS4 Target',
           AVG(G1.Pointscore - G2.Pointscore) AS 'Average Residual',
           SUM(1) AS 'No. Students',
           ...
    FROM Students S
    ...
) t

更新：

我还尝试通过以下方式切换到管道运算符进行串联：

SET sql_mode = 'PIPES_AS_CONCAT'

然后通过

与SUM(1)连接

SELECT 'Disadvantaged (' || SUM(1) || ')'

但这也没有用。这是一个 Fiddle 似乎表明切换到管道运算符也不起作用：

MySQL SELECT CONCAT() 列输出中的意外值

Unexpected values in MySQL SELECT CONCAT() column output

mysql

string

concat

function

concatenation

SQLFiddle