android sqlite数据库query函数问题
0 [待解决问题] package com.example.foolishfan.user_v10;
/** Created by FoolishFan on 2016/7/14.主要是用户信息的管理操作
*/
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class UserDataManager { //用户数据管理类
//一些宏定义和声明
private static final String TAG = "UserDataManager";
private static final String DB_NAME = "user_data";
private static final String TABLE_NAME = "users";
public static final String ID = "_id";
public static final String USER_NAME = "user_name";
public static final String USER_PWD = "user_pwd";
// public static final String SILENT = "silent";
// public static final String VIBRATE = "vibrate";
private static final int DB_VERSION = 2;
private Context mContext = null; //创建用户book表 private static final String DB_CREATE = "CREATE TABLE " + TABLE_NAME + " (" + ID + " integer primary key," + USER_NAME + " varchar," + USER_PWD + " varchar" + ");"; private SQLiteDatabase mSQLiteDatabase = null; private DataBaseManagementHelper mDatabaseHelper = null; //DataBaseManagementHelper继承自SQLiteOpenHelper private static class DataBaseManagementHelper extends SQLiteOpenHelper { DataBaseManagementHelper(Context context) { super(context, DB_NAME, null, DB_VERSION); } @Override public void onCreate(SQLiteDatabase db) { Log.i(TAG,"db.getVersion()="+db.getVersion()); db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME + ";"); db.execSQL(DB_CREATE); Log.i(TAG, "db.execSQL(DB_CREATE)"); Log.e(TAG, DB_CREATE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.i(TAG, "DataBaseManagementHelper onUpgrade"); onCreate(db); } } public UserDataManager(Context context) { mContext = context; Log.i(TAG, "UserDataManager construction!"); } //打开数据库 public void openDataBase() throws SQLException { mDatabaseHelper = new DataBaseManagementHelper(mContext); mSQLiteDatabase = mDatabaseHelper.getWritableDatabase(); } //关闭数据库 public void closeDataBase() throws SQLException { mDatabaseHelper.close(); } //添加新用户，即注册 public long insertUserData(UserData userData) { String userName=userData.getUserName(); String userPwd=userData.getUserPwd(); ContentValues values = new ContentValues(); values.put(USER_NAME, userName); values.put(USER_PWD, userPwd); return mSQLiteDatabase.insert(TABLE_NAME, ID, values); } //更新用户信息，如修改密码 public boolean updateUserData(UserData userData) { //int id = userData.getUserId(); String userName = userData.getUserName(); String userPwd = userData.getUserPwd(); ContentValues values = new ContentValues(); values.put(USER_NAME, userName); values.put(USER_PWD, userPwd); return mSQLiteDatabase.update(TABLE_NAME, values,null, null) > 0; //return mSQLiteDatabase.update(TABLE_NAME, values, ID + "=" + id, null) > 0; } // public Cursor fetchUserData(int id) throws SQLException { Cursor mCursor = mSQLiteDatabase.query(false, TABLE_NAME, null, ID + "=" + id, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } // public Cursor fetchAllUserDatas() { return mSQLiteDatabase.query(TABLE_NAME, null, null, null, null, null, null); } //根据id删除用户 public boolean deleteUserData(int id) { return mSQLiteDatabase.delete(TABLE_NAME, ID + "=" + id, null) > 0; } //根据用户名注销 public boolean deleteUserDatabyname(String name) { return mSQLiteDatabase.delete(TABLE_NAME, USER_NAME + "=" + name, null) > 0; } //删除所有用户 public boolean deleteAllUserDatas() { return mSQLiteDatabase.delete(TABLE_NAME, null, null) > 0; } // public String getStringByColumnName(String columnName, int id) { Cursor mCursor = fetchUserData(id); int columnIndex = mCursor.getColumnIndex(columnName); String columnValue = mCursor.getString(columnIndex); mCursor.close(); return columnValue; } // public boolean updateUserDataById(String columnName, int id, String columnValue) { ContentValues values = new ContentValues(); values.put(columnName, columnValue); return mSQLiteDatabase.update(TABLE_NAME, values, ID + "=" + id, null) > 0; } //根据用户名找用户，可以判断注册时用户名是否已经存在 public int findUserByName(String userName){ Log.i(TAG,"findUserByName , userName="+userName); int result=0; Cursor mCursor=mSQLiteDatabase.query(TABLE_NAME, null, USER_NAME+"="+userName, null, null, null, null); if(mCursor!=null){ result=mCursor.getCount(); mCursor.close(); Log.i(TAG,"findUserByName , result="+result); } return result; } //根据用户名和密码找用户，用于登录 public int findUserByNameAndPwd(String userName,String pwd){ Log.i(TAG,"findUserByNameAndPwd"); int result=0; Cursor mCursor=mSQLiteDatabase.query(TABLE_NAME, null, USER_NAME+"="+userName+" and "+USER_PWD+"="+pwd, null, null, null, null); if(mCursor!=null){ result=mCursor.getCount(); mCursor.close(); Log.i(TAG,"findUserByNameAndPwd , result="+result); } return result; }
}
我觉得是Cursor mCursor=mSQLiteDatabase.query(TABLE_NAME, null, USER_NAME+"="+userName, null, null, null, null); 这里出问题
请问有大佬知道这个语句哪里出错了吗，select where不是这样用吗？
pipi_pig | 菜鸟二级 | 园豆： 202
提问于：2019-05-27 00:34 显示帮助
使用"Ctrl+Enter"可进行快捷提交，评论支持部分 Markdown 语法：[link](http://example.com) _italic_ **bold** `code`。
< > 分享
分享您的问题

清除回答草稿
您需要 登录 以后才能回答，未注册用户请先 注册 。