Question

我正在尝试将SELECT查询保留在Android的光标中
我使用此查询：

Cursor cursor = myDb.rawQuery("SELECT * FROM tbl_main_words WHERE word_id BETWEEN 1 AND 500 ORDER BY word_eng",null)

和cursor.getCount（）返回0！
与（<）查询相同！
而不应该是:(
因为我的myDb表中有15000行，word_id从1到15000

注意：问题不是来自数据库，因为我可以从某些查询中返回真实值，例如：

SELECT * FROM tbl_main_words WHERE word_id > 0 ORDER BY word_eng

重要提示：在某些SQLite软件（例如SQLite Expert）中，这些查询的执行没有问题！

Answer 1

我不认为您的问题与查询有关，使用：-

可以正常工作

public class SO51108624DBHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "worddb";
    public static final int DBVERSION = 1;

    public static final String TB_MAIN_WORDS = "tbl_main_words";
    public static final String COL_WORDID = "word_id";
    public static final String COL_WORDENG = "word_eng";

    SQLiteDatabase mDB;

    public SO51108624DBHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
        mDB = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String crtsql = "CREATE TABLE IF NOT EXISTS " + TB_MAIN_WORDS + "(" +
                COL_WORDID + " INTEGER PRIMARY KEY," +
                COL_WORDENG + " TEXT" +
                ")";
        db.execSQL(crtsql);

    }


    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }

    public long addRow(String word) {
        ContentValues cv = new ContentValues();
        cv.put(COL_WORDENG,word);
        return mDB.insert(TB_MAIN_WORDS,null,cv);
    }

    public void populateMainWordsTable() {
        mDB.delete(TB_MAIN_WORDS,null,null);
        for (int i=0; i < 1000; i++) {
            addRow("test");
        }
    }

    public int getWordCountBetweenIDs() {
        String sql = "SELECT * FROM tbl_main_words WHERE word_id BETWEEN 1 AND 500 ORDER BY word_eng";
        Cursor csr = mDB.rawQuery(sql,null);
        int rv = csr.getCount();
        csr.close();
        return rv;
    }
}

以及：-

    SO51108624DBHelper mDBHlpr = new SO51108624DBHelper(this);
    mDBHlpr.populateMainWordsTable();
    int rowcount = mDBHlpr.getWordCountBetweenIDs();
    Log.d("ROWCOUNT", "Number of rows returned was " + String.valueOf(rowcount));

产生：-

06-29 22:29:39.193 1452-1452/soanswers.soanswers D/ROWCOUNT: Number of rows returned was 500

因此，当您运行此表时，表本身很可能为空。假设您没有遗漏任何错误，例如找不到列/表。

您可以尝试使用：-

Log.d ("ROWCOUNT","Number of rows in tbl_main_words is " + String.valueOf(DatabaseUtils.queryNumEntries(myDb,"tbl_main_words")));
Cursor cursor = myDb.rawQuery("SELECT * FROM tbl_main_words WHERE word_id BETWEEN 1 AND 500 ORDER BY word_eng",null)

，然后检查日志，其内容应类似于：-

06-29 22：36：54.232 1529-1529 / soanswers.soanswers D / ROWCOUNT： tbl_main_words中的行是1000

SQLite-BETWEEN和GREATER THAN（<）在游标中始终返回0

1 个答案: