Question

public Cursor fetchTimetable() {
    return mDb.query(DATABASE_TABLE_TIMETABLE, new String[] {TIMETABLE_ROWID,    TIMETABLE_MODULECODE, TIMETABLE_MODULENAME, TIMETABLE_ROOM, TIMETABLE_LECTURER, TIMETABLE_TIME}, null, null, null, null, null);
}

例如，如果我想要TIMETABLE_MODULECODE = 123.我将如何做到这一点，我已经读过第一个null。我在下面尝试了这个，但仍然无法正常工作

public Cursor fetchTimetable() {
    String a = "TIMETABLE_CODE = ADD";
    return mDb.query(DATABASE_TABLE_TIMETABLE, new String[] {TIMETABLE_ROWID, TIMETABLE_MODULECODE, TIMETABLE_MODULENAME, TIMETABLE_ROOM, TIMETABLE_LECTURER, TIMETABLE_TIME}, a, null, null, null, null);
}

Answer 1

我在args的工作示例（使用它时更清楚）：

        String [] settingsProjection = {
                DBContract.Settings._ID,
                DBContract.Settings.COLUMN_NAME_USER_ID,
                DBContract.Settings.COLUMN_NAME_AUTO_LOGIN
        };

        String whereClause = DBContract.Settings.COLUMN_NAME_USER_ID+"=?";
        String [] whereArgs = {userId.toString()};

        Cursor c = db.query(
                DBContract.Settings.TABLE_NAME,
                settingsProjection,
                whereClause,
                whereArgs,
                null,
                null,
                null
        );

Answer 2

db.query
        (
                TABLE_NAME,
                new String[] { TABLE_ROW_ID, TABLE_ROW_ONE, TABLE_ROW_TWO },
                TABLE_ROW_ID + "=" + rowID,
                null, null, null, null, null
        );

TABLE_ROW_ID +“=”+ rowID，此处“=”是where子句

Answer 3

究竟什么“仍然不起作用”是什么意思？

以下代码应该可以正常工作：

public Cursor fetchTimetable() { 
    String[] columnNames = new String[] {TIMETABLE_ROWID, TIMETABLE_MODULECODE, TIMETABLE_MODULENAME, TIMETABLE_ROOM, TIMETABLE_LECTURER, TIMETABLE_TIME};
    String whereClause = "TIMETABLE_MODULECODE=123"; 

    return mDb.query(DATABASE_TABLE_TIMETABLE, columnNames, whereClause, null, null, null, null); 
}

Answer 4

正确的语法是

String[] projection= {column names};
String[] where={"values for where clause"}; //this must be array     
public Cursor fetchTimetable() { 

    return mDb.query(TABLE_NAME, projrction, "columname"+"=?", where, null, null, null); 
}

Answer 5

简单的方法：

return mDb.rawQuery("SELECT * FROM myTable WHERE column1 = "+ someValue, null);

Answer 6

您可以使用此查询：

SQLiteDatabase db = this.getReadableDatabase();

//Cursor cursorr = db.rawQuery(Query, null);

Cursor cursorr =  db.rawQuery("select * from " + DATABASE_TABLE_EHS + " where " + TASK_ID + "='" + taskid + "'" , null);

    if (cursorr.moveToFirst()) 
   {

        do {

            // your code like get columns

            }
         while (cursorr.moveToNext());
    }
}

Answer 7

如果您正在检查字符串值，那么您希望将字符串换成如下所示的引号：

dbHelper.COL_EMAIL +"='"+givenEmail+"'",

SQLiteDatabase - 如何使用where子句？

7 个答案: