Android：使用字符串更新数据库时出错答案

【问题标题】：Android: Error when updating database using a stringAndroid：使用字符串更新数据库时出错
【发布时间】：2014-11-17 13:21:06
【问题描述】：

我的数据库包含音乐会列表，我正在根据名称列更新它们。单击更新按钮时，将传入给定 Concert 的列值。但是，仅当名称列是单个数字时，更新才有效。如果名称列是一个字符串或 2+ 位数字，它会立即崩溃并给我以下错误。

11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ Update artist method: Value of name = test
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ Update artist method: Value of venue = test venue
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ Update artist method: Value of date = dd
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ Update artist method: Value of comments = d
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ DB Manager method: Value of name = test
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ DB Manager method: Value of venue = test venue
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ DB Manager method: Value of date = dd
11-17 13:14:51.325  12131-12131/com.example.msdproject I/test﹕ DB Manager method: Value of comments = d
11-17 13:14:51.325  12131-12131/com.example.msdproject E/SQLiteLog﹕ (1) no such column: test
11-17 13:14:51.335  12131-12131/com.example.msdproject D/AndroidRuntime﹕ Shutting down VM
11-17 13:14:51.335  12131-12131/com.example.msdproject W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41614ba8)
11-17 13:14:51.355  12131-12131/com.example.msdproject E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.msdproject, PID: 12131
    android.database.sqlite.SQLiteException: no such column: test (code 1): , while compiling: UPDATE Concert_Info SET date=?,venue=?,comments=?,name=? WHERE name=test
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
        at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
        at android.database.sqlite.SQLiteDatabase.updateWithOnConflict(SQLiteDatabase.java:1572)
        at android.database.sqlite.SQLiteDatabase.update(SQLiteDatabase.java:1520)
        at com.example.msdproject.DBManager.updateConcert(DBManager.java:150)
        at com.example.msdproject.UpdateArtist.UpdateArtistButton(UpdateArtist.java:103)
        at com.example.msdproject.UpdateArtist$1.onClick(UpdateArtist.java:79)
        at android.view.View.performClick(View.java:4438)
        at android.view.View$PerformClick.run(View.java:18422)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5001)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
        at dalvik.system.NativeStart.main(Native Method)
11-17 13:14:51.365  12131-12131/com.example.msdproject D/dalvikvm﹕ GC_FOR_ALLOC freed 591K, 4% free 17167K/17788K, paused 9ms, total 9ms
11-17 13:14:53.245  12903-12903/com.example.msdproject I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:320>: EGL 1.4 QUALCOMM Build: I0404c4692afb8623f95c43aeb6d5e13ed4b30ddbDate: 11/06/13
11-17 13:14:53.275  12903-12903/com.example.msdproject D/OpenGLRenderer﹕ Enabling debug mode 0

它的基本意思是该列不存在，但我不明白为什么它给我这个错误，因为当我使用单个数字时它识别出该列存在。我尝试按 _id 删除，但这给了我相同的结果，所以我恢复为按名称列删除。关于可以传递给数据库更新函数的内容是否有例外？

这里是 updateArtist 类：

package com.example.msdproject;

import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.sql.SQLException;

public class UpdateArtist extends Activity {

    DBManager db = new DBManager(this);

    public EditText nameTxt;
    public EditText venueTxt;
    public EditText dateTxt;
    public EditText commentsTxt;

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

        Intent intent = getIntent();
        final long num = intent.getLongExtra("id", 1);

        try {
            db.open();
            Cursor c = db.getConcert(num);
            if (c.moveToFirst())
            {
                do
                {
                    String name = (c.getString(1));
                    String venue = (c.getString(2));
                    String date = (c.getString(3));
                    String comments = (c.getString(4));

                    TextView titleTxt = (TextView)findViewById(R.id.updateTitle);
                    nameTxt = (EditText)findViewById(R.id.updateName);
                    venueTxt = (EditText)findViewById(R.id.updateVenue);
                    dateTxt = (EditText)findViewById(R.id.updateDate);
                    commentsTxt = (EditText)findViewById(R.id.updateComments);


                    titleTxt.setText(name);
                    nameTxt.setText(name);
                    venueTxt.setText(venue);
                    dateTxt.setText(date);
                    commentsTxt.setText(comments);

                    Button update = (Button)findViewById(R.id.updateConcertButton);
                    update.setOnClickListener(new View.OnClickListener()
                    {
                        @Override
                        public void onClick(View v)
                        {
                            if (nameTxt.getText().toString().isEmpty()  || venueTxt.getText().toString().isEmpty() ||
                                    dateTxt.getText().toString().isEmpty() || commentsTxt.getText().toString().isEmpty() )
                            {
                                Toast.makeText(UpdateArtist.this, "Error! Please fill in all fields", Toast.LENGTH_LONG).show();
                            }
                            else
                            {

                                String updatedName = nameTxt.getText().toString();
                                String updatedVenue = venueTxt.getText().toString();
                                String updatedDate = dateTxt.getText().toString();
                                String updatedComments = commentsTxt.getText().toString();

                                UpdateArtistButton(updatedName,updatedVenue,updatedDate,updatedComments);
                            }
                        }
                    });

                } while (c.moveToNext());
            }
        }

        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public void UpdateArtistButton(String passedName, String passedVenue, String passedDate, String passedComments)
    {
        try
        {
            db.open();
            Log.i("test", "Update artist method: Value of name = " + passedName);
            Log.i("test", "Update artist method: Value of venue = " + passedVenue);
            Log.i("test", "Update artist method: Value of date = " + passedDate);
            Log.i("test", "Update artist method: Value of comments = " + passedComments);
            db.updateConcert(passedName,passedVenue, passedDate, passedComments);
            Toast.makeText(UpdateArtist.this, "Concert Updated!", Toast.LENGTH_LONG).show();
            super.finish();
        }

        catch (SQLException e)
        {
            e.printStackTrace();
        }

        db.close();
    }
}

这是 DBManager 类：

package com.example.msdproject;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.content.Context;
import android.util.Log;

import java.sql.SQLException;


public class DBManager {

    public static final String COL_ROWID = "_id";
    public static final String COL_NAME = "name";
    public static final String COL_VENUE = "venue";
    public static final String COL_DATE = "date";
    public static final String COL_COMMENTS = "comments";

    private static final String DB_NAME = "Concerts";
    private static final String DB_TABLE = "Concert_Info";
    private static final int DB_VERSION = 1;

    private static final String DB_CREATE =
            "create table " + DB_TABLE + 
    " (_id integer primary key autoincrement, " +
            "name text not null, " +
            "venue text not null, " +
            "comments text not null, " +
            "date text not null);";

    private final Context context;

    private DatabaseHelper DBHelper;
    private SQLiteDatabase db;

    public DBManager(Context ctx)
    {
        this.context = ctx;
        DBHelper = new DatabaseHelper(context);
    }

    public static class DatabaseHelper extends SQLiteOpenHelper
    {
        DatabaseHelper(Context context)
        {
            super(context, DB_NAME, null, DB_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db)
        {
            db.execSQL(DB_CREATE);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
        {
            /*
            //taken from YouTube Tutorial video
            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                    + newVersion + ", which will destroy all old data");
            db.execSQL("drop table if exists Concert_Info");
            onCreate(db);*/
        }
    }

    public DBManager open() throws SQLException
    {
        db = DBHelper.getWritableDatabase();
        //db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE + ";");
        return this;
    }

    public void close()
    {
        DBHelper.close();
    }

    public long insertConcert(String name, String venue, String date, String comments)
    {
        ContentValues initialValues = new ContentValues();
        initialValues.put(COL_NAME, name);
        initialValues.put(COL_VENUE, venue);
        initialValues.put(COL_DATE, date);
        initialValues.put(COL_COMMENTS, comments);
        return db.insert(DB_TABLE, null, initialValues);
    }

    public boolean deleteConcert(String name)
    {
        return db.delete(DB_TABLE, COL_NAME + "=" + name, null) > 0;
    }

    public Cursor getAllConcerts() {
        return db.query(DB_TABLE, new String[]
                        {
                                COL_ROWID,
                                COL_NAME,
                                COL_VENUE,
                                COL_DATE,
                                COL_COMMENTS
                        },
                        null,
                        null,
                        null,
                        null,
                        null,
                        null
                );
    }

    public Cursor getConcert(long ROW_ID) throws SQLException
    {
        Cursor mCursor =
                db.query(DB_TABLE, new String[]
                        {
                                COL_ROWID,
                                COL_NAME,
                                COL_VENUE,
                                COL_DATE,
                                COL_COMMENTS
                        },
                        COL_ROWID + "=" + ROW_ID,
                        null,
                        null,
                        null,
                        null
                );
        if (mCursor != null)
        {
            mCursor.moveToFirst();
        }

        return mCursor;
    }

    public boolean updateConcert(String name, String venue, String date, String comments)
    {
        ContentValues updateValues = new ContentValues();
        updateValues.put(COL_NAME, name);
        updateValues.put(COL_VENUE, venue);
        updateValues.put(COL_DATE, date);
        updateValues.put(COL_COMMENTS, comments);
        Log.i("test", "DB Manager method: Value of name = " + name);
        Log.i("test", "DB Manager method: Value of venue = " + venue);
        Log.i("test", "DB Manager method: Value of date = " + date);
        Log.i("test", "DB Manager method: Value of comments = " + comments);
        return db.update(DB_TABLE, updateValues, "name"  + "=" + name, null) > 0;
    }

    public void reset () throws SQLException {
        db.delete(DB_TABLE, null, null);
        db.close();
        this.DBHelper.onCreate(this.db);
    }
}

【问题讨论】：

试试这个return db.update(DB_TABLE, updateValues, "name='"+ name+"'", null) > 0;
@MD 啊谢谢！我认为这可能与分隔符有关，但是当我尝试单引号时，我不断收到字符串文字错误。我从没想过要那样做。再次感谢

标签： android database string

【解决方案1】：

值应该被引用：

return db.update(DB_TABLE, updateValues, "name"  + "='" + name +"'", null) > 0

【讨论】：

【解决方案2】：

您的代码中的问题是： WHERE 名称=测试

您的查询已损坏。

测试是字段的值还是名称？取决于测试的语义，你有 3 种方法来解决这个问题：

如果它是一个 sqlite-field 的名称，那么您的表缺少该字段，您应该将其添加到您的 sqlite-table 中。
应该是测试一个值，然后你必须在这个周围使用'。
如果 test 是您的 java 代码中的一个变量，那么您必须将该变量的值插入到查询中并连接 f.e.

【讨论】：