如何将 WHERE 子句添加到 android 上的查询
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how to add WHERE clause to Query on android
提问by Brian
I would like to limit the results to those whose KEY_HOMEID is equal to journalId. I've been on this for a couple days any help would be appreciated.
我想将结果限制为那些 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);
}
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);
}
回答by m6tt
Have a look at http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#query
看看http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#query
Your query should look a little like this:
您的查询应如下所示：
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
);
If you feel more comfortable writing sql queries you can also use:
如果您觉得编写 sql 查询更舒服，您还可以使用：
mDb.rawQuery("SQL STATEMENT", null);
回答by Krystian
It makes your code more clear if you'll use it where arguments (in query parameters) Example:
如果您将在 where 参数（在查询参数中）使用它，它会使您的代码更加清晰 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
);
回答by Robi Wan Kenobi
I was looking for an answer to my problem here as well.
我也在这里寻找我的问题的答案。
It turned out that I tried to have a String instead of an Integer. My solution was to do it like that: 'String' instead of Integer.
原来我试图用一个字符串而不是一个整数。我的解决方案是这样做：'String' 而不是 Integer。
Here is the code that worked for me in the end:
这是最终对我有用的代码：
return db.query(TABLE_NAME_REMINDER, PROJECTION, REMINDER_REMINDER_TYPE+" = '"+rem_type+"'", null, null, null, null);
