Question

我正在尝试从空表中获取数据并显示＆＃34;没有这样的表错误＆＃34;。这是我的数据库适配器代码。

DBAdapter.java

package com.prome.testdatabase;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;

/**
 * @author Md. Nabid Imteaj
 * @version 0.1
 * @see Database adapter for creating local databases
 * and also for local queries.
 */
public class DBAdapter {
    // define tag
    public static final String TAG = "DBAdapter";
    // define table fields
    static final String KEY_ID = "_id";
    static final String KEY_NAME = "name";

    // define table names
    static final String TABLE_INFO = "info";
    // define database name
    static final String DATABASE_NAME = "test_db_debug";
    // define database version
    static final int DATABASE_VERSION = 1;
    // define separators
    static final String COMMA_SEP = ", ";
    static final String IPA_SEP = " integer primary autoincrement ";
    static final String INT_SEP = " integer";
    static final String TEXT_SEP = " TEXT";
    // define database creation queries
    static final String CREATE_INFO = "create table " + TABLE_INFO + "( "
                                            + KEY_ID + IPA_SEP + COMMA_SEP
                                            + KEY_NAME + TEXT_SEP +" )";

    final Context context;
    DatabaseHelper DBHelper;
    SQLiteDatabase db;

    // Constructor. Creates database.
    public DBAdapter( Context ctx ) {
        this.context = ctx;
        // create database
        DBHelper = new DatabaseHelper(context);
    }

    // ----- make private class -----
    private class DatabaseHelper extends SQLiteOpenHelper {

        // constructor
        public DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
            //Toast.makeText(context, "DatabaseHelper Constructor", Toast.LENGTH_LONG).show();
            Log.d(TAG, "DatabseHelper Constructor Loaded.");
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            // TODO Auto-generated method stub
            // create databases
            try {
                db.execSQL(CREATE_INFO);
                Log.d(TAG, "All tables has been created.");
            } catch(Exception e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            // TODO Auto-generated method stub
            Log.d( TAG, "Updating database from version " + oldVersion + " to " + newVersion +
                    ", which will destroy all old data.");
            String drp = "DROP TABLE IF EXISTS ";

            db.execSQL( drp + TABLE_INFO );

            onCreate(db);
        }   
    } // ----- ends private class ------

    // --- opens the database ---
    public DBAdapter open() {
        db = DBHelper.getWritableDatabase();
        Log.d(TAG, "Database opened.");
        return this;
    }

    // --- closes the database ---
    public void close() {
        DBHelper.close();
        Log.d(TAG, "Database closed.");
    }

    // get all data of table
    public Cursor getAllData() {
        return db.query(TABLE_INFO, new String[]{ KEY_ID, KEY_NAME }, null, null, null, null, null);
    }
}

在MainActivity.java中＆gt; onCreate（）方法：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    DBAdapter db = new DBAdapter(this);
    db.open();
    Cursor c = db.getAllData();
    while( !c.isAfterLast() ) {
        Log.d("DB", "id: "+c.getString(0)+", name: "+c.getString(1));
        c.moveToNext();
    }
    db.close();
}

请解释缺陷的内容和位置并给出解决方案。提前谢谢。

Answer 1

CREATE TABLE中存在语法错误。 integer primary autoincrement应为integer primary key autoincrement。

修复语法错误后，卸载您的应用，以便重新创建数据库文件。

为什么它之前没有失败是因为你在onCreate()中捕获异常。这是个坏主意。问题需要向上传播，以便SQLiteOpenHelper不会认为数据库设置没有成功。

Android SQLite数据库错误 - 没有这样的表

1 个答案: