Sqlite Android 按 & group_concat 排序

Question

我正在使用 sqlite3 : 3.8.2 和 sqliteman (Ubuntu 14.04) 来尝试我的程序中需要的查询 Android.

Android 版本 4.0+。

我有3个table用来获取数据

我发现了这个问题：

当我在 sqliteman 中使用这个查询时

SELECT st.nome
AS nome,
st.cognome
AS cognome, 
(SELECT ae.usercode
AS usercode
FROM assenze ae
WHERE st.ultimo_evento = ae.fk_evento)
AS ultimo_evento,
(SELECT 
    GROUP_CONCAT(
        ev.nome_evento, ", "
    )
    AS nome_evento 
    FROM eventi ev 
    WHERE ev.studente_id = st.id 
)
AS nome_evento
FROM studenti st 
WHERE st.classe_ident ='4297'
ORDER BY st.cognome

输出为：

EP, USC, R1, R, A ... 非常适合我

但是当我在 android 和 db.rawQuery() 中使用它时，结果是

A, EP, R, R1, USC ... 对我没好处

似乎也是这个查询的相同结果（在sqliteman和android中执行）：

SELECT 
st.nome AS nome, 
st.cognome AS cognome, 
ae.usercode AS ultimo_evento, 
GROUP_CONCAT(
   ev.nome_evento, ", "
) 
AS nome_evento
FROM studenti st
LEFT JOIN eventi ev
ON st.id = ev.studente_id
LEFT JOIN assenze ae
ON st.ultimo_evento = ae.fk_evento
WHERE st.classe_ident ='4297'
GROUP BY st.id
ORDER BY st.cognome

可能是我的错，但我仍在努力寻找解决方案...

谢谢

似乎它在没有 ORDER BY ev.data_ora_evento 的情况下也能工作。但是在 android 仍然无法正常工作...

Answer 1

group_concat() documentation 说：

The order of the concatenated elements is arbitrary.

但是，您可以尝试通过对已排序的子查询执行 group_concat() 来强制排序：

SELECT GROUP_CONCAT(ev.nome_evento, ", ") AS nome_evento 
FROM (SELECT nome_evento
      FROM eventi
      WHERE studente_id = st.id
      ORDER BY whatever) AS ev

Sqlite Android 按 & group_concat 排序

Sqlite Android order by & group_concat

sqlite

android

sql-order-by

group-concat