如何在android上的Query中添加WHERE子句

Question

我想将结果限制为KEY_HOMEID等于journalId的结果.我已经在这几天了,任何帮助将不胜感激.

public Cursor fetchAllNotes(String journalId) { return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_HEIGHT, KEY_BODY, KEY_HOMEID},"FROM DATABASE_TABLE WHERE KEY_HOMEID = journalId",null, null, null, null,null); }

Answer 1

看看http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#query

您的查询应该看起来像这样:

mDb.query(DATABASE_TABLE, // Table name
          columnNames, // String[] containing your column names
          KEY_HOMEID+" = "+jounalId, // your where statement, you do not include the WHERE or the FROM DATABASE_TABLE parts of the query,
          null,
          null,
          null,
          null
         );

如果您对编写SQL查询感觉更舒服,您还可以使用:

mDb.rawQuery("SQL STATEMENT", null);

Answer 2

如果你在参数(在查询参数中)使用它,它会使你的代码更清晰示例:

        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
        );