Question

我在数据库中有两个表，我想使用left-join

来检索它们

 public Cursor readData()
    {
        Cursor c=database.rawQuery(" SELECT _id, i.Date, i.TimeIn_Info, i.TimeOut_Info, S.Image FROM " + MyDatabaseHelper.TABLE_INFO +"i LEFT JOIN"+MyDatabaseHelper.TABLE_STAFF_BENEFIT+" S ON S.Ts_id=i.ID WHERE i.Name = ?", new String[]{"XCV"}, null);

        if (c != null) {
            c.moveToFirst();
        }
        return c;
    }

然而，应用程序崩溃了。这有什么不对？感谢

LogCat错误

 Process: com.example.project.myapplication, PID: 4861
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.project.myapplication/com.example.project.myapplication.MainActivity}: android.database.sqlite.SQLiteException: near "ON": syntax error (code 1): , while compiling: SELECT _id, i.Date, i.TimeIn_Info, i.TimeOut_Info, S.Image FROM Informationi LEFT JOINStaffBenefit S ON S.Ts_id=i.ID WHERE i.Name = ?
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2447)

表格信息

 db.execSQL("create table " + TABLE_INFO + " ( " + ID + " INTEGER PRIMARY KEY ,Name TEXT,Weather TEXT, Date DATETIME, Status Text, TimeIn_Info DATE TIME, TimeOut_Info DATETIME)");  //ID=_id

表Staff_Benefit

 db.execSQL("create table " + TABLE_STAFF_BENEFIT + "( "  + ID3 + " INTEGER PRIMARY KEY , Claim_Type TEXT, Image BLOB, Description TEXT , Amount TEXT, Ts_id INTEGER, FOREIGN KEY(Ts_id) REFERENCES "+TABLE_INFO+"(_id))"); //ID3=_id

LogCat

Caused by: android.database.sqlite.SQLiteException: ambiguous column name: _id (code 1): , while compiling: SELECT _id, i.Date, i.TimeIn_Info, i.TimeOut_Info, S.Image FROM Information i LEFT JOIN StaffBenefit S ON S.Ts_id=i._ID WHERE i.Name = ? 
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)

最新查询

Cursor c=database.rawQuery(" SELECT _id, i.Date, i.TimeIn_Info, i.TimeOut_Info, S.Image FROM " + MyDatabaseHelper.TABLE_INFO + " i LEFT JOIN "+MyDatabaseHelper.TABLE_STAFF_BENEFIT+" S ON S.Ts_id=i._ID WHERE i.Name = ?", new String[]{"XCV"}, null);

Answer 1

标识符和关键字之间需要空格。特别是，替换

"i LEFT JOIN"

与

" i LEFT JOIN "

Answer 2

为了解决我的第二个问题，

替换为Cursor c=database.rawQuery(" SELECT i._id, i.Date, i.TimeIn_Info, i.TimeOut_Info, S.Image FROM " + MyDatabaseHelper.TABLE_INFO + " i LEFT JOIN "+MyDatabaseHelper.TABLE_STAFF_BENEFIT+" S ON S.Ts_id=i._id WHERE i.Name = ?", new String[]{"XCV"}, null);

android.database.sqlite.SQLiteException：接近“ON”：语法错误（代码1）：

2 个答案: