我有兩個表一個存儲任務和一個評估任務:SQLite視圖和查詢在Android
create table task(
_id integer primary key autoincrement,
task text not null);
create table eval (
_id integer primary key autoincrement,
taskid integer,
eval integer);
一些數據:
INSERT INTO task VALUES (1,"A small job");
INSERT INTO task VALUES (2,"A easy job");
INSERT INTO eval VALUES (1,1,1);
INSERT INTO eval VALUES (2,1,2);
INSERT INTO eval VALUES (3,2,1);
INSERT INTO eval VALUES (4,2,2);
然後連接兩個表的視圖:
CREATE VIEW status AS
SELECT eval._id AS _id,
eval.taskid AS taskid,
eval.eval AS eval,
task.task
FROM task JOIN eval
ON task._id = eval.taskid;
SQLite數據庫瀏覽器不支持視圖。什麼是一個好的數據庫瀏覽器在Linux上的Android開發?
其次,考慮這個查詢:
s.task s.eval
A easy job 2
A small job 2
如何實現在Android應用此查詢:每個任務
SELECT s.task, s.eval
FROM status AS s
JOIN (
SELECT task, MAX(eval) AS maxeval
FROM status
GROUP BY task
) AS pm ON s.task = pm.task AND s.eval = pm.maxeval;
,導致選擇的最高評價?我試圖將它裝入Cursor android.database.sqlite.SQLiteDatabase.query
方法和它的兄弟姐妹沒有多少運氣。
有沒有辦法將SQL查詢作爲字符串傳遞到數據庫中並獲取結果集?
SQLiteDatabase.execSql(String); – f470071 2015-09-26 12:36:58