Question

我正在尝试研究并创建一个简单的数据库，创建一个只有一行的表。我首先看到它在我使用SQLiteHelper的'update（）'方法时有效。但是，当我使用SQL命令'UPDATE ... SET'尝试它时，它会抛出一个'没有这样的列'的错误

我不知道为什么我不能使用'UPDATE ... SET'命令，因为'update'方法没有问题。如果有人知道android SQL，你能帮帮我吗？以下是我的代码和错误消息。

CODE：

public class TestDBMain extends Activity {
private final String SETTINGS_TABLE_NAME = "settings";

// Columns
private final String DEV_ID = "dev_id";
private final String SERVER_NAME = "server_name";
private final String SERVER_PORT = "server_port";
private final String SERVER_SUBFOLDER = "server_subfolder";
private final String USERNAME = "username";
private final String PASSWORD = "password";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    DB_Settings db_s = new DB_Settings(this);
    db_s.deleteDBSettings();
    db_s.addDBSettings(SERVER_NAME, "test_server_01");
    // ERROR occurs here
    db_s.addDBSettingsWithSQLCommand(SERVER_NAME, "test_server_22");
}

public class DB_Settings extends SQLiteOpenHelper {
    private static final String DB_NAME = "settings.db";
    private static final int DATABASE_VERSION = 1;
    private String[] Settings_FROM = { _ID, DEV_ID, SERVER_NAME, SERVER_PORT, SERVER_SUBFOLDER, 
            USERNAME, PASSWORD};

    private Context mContext;

    public DB_Settings(Context context) {
        super(context, DB_NAME, null, DATABASE_VERSION);
        mContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE IF NOT EXISTS "+SETTINGS_TABLE_NAME+"("+_ID+" INTEGER PRIMARY KEY AUTOINCREMENT, "
                +DEV_ID+" VARCHAR,"
                +SERVER_NAME+" VARCHAR,"
                +SERVER_PORT+" INTEGER,"
                +SERVER_SUBFOLDER+" VARCHAR,"
                +USERNAME+" VARCHAR,"
                +PASSWORD+" VARCHAR);");        

        initialize(db);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    public void deleteDBSettings(){
        mContext.deleteDatabase(DB_NAME);
    }

    private void initialize(SQLiteDatabase db){
        ContentValues values = new ContentValues();

        values.put(DEV_ID, "1");
        values.put(SERVER_NAME, "1");
        values.put(SERVER_PORT, 443);
        values.put(SERVER_SUBFOLDER, "1");
        values.put(USERNAME, "1");
        values.put(PASSWORD, "1");

        db.insertOrThrow(SETTINGS_TABLE_NAME, null, values);
    }

    public void addDBSettings(String key, Object value){
        // Insert a new record
        SQLiteDatabase db = getWritableDatabase();
        ContentValues table_value = new ContentValues();

        if(value.getClass().equals(String.class)){
            table_value.put(key, value.toString());
        }
        else if (value.getClass().equals(Integer.class)){
            table_value.put(key, (Integer)value);
        }

        // add to database
        db.update(SETTINGS_TABLE_NAME, table_value, "_id=1", null);
    }

    public void addDBSettingsWithSQLCommand(String key, Object value){
        SQLiteDatabase db = getWritableDatabase();
        db.execSQL("UPDATE "+SETTINGS_TABLE_NAME
                +" set "+key+" = "+value.toString()
                +" where _id = 1;");
    }
 }

错误日志：

07-20 01:00:53.516: ERROR/AndroidRuntime(6066): Caused by: android.database.sqlite.SQLiteException: no such column: test_server_22: UPDATE settings set server_name = test_server_22 where _id = 1;
07-20 01:00:53.516: ERROR/AndroidRuntime(6066):     at android.database.sqlite.SQLiteDatabase.native_execSQL(Native Method)
07-20 01:00:53.516: ERROR/AndroidRuntime(6066):     at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1727)
07-20 01:00:53.516: ERROR/AndroidRuntime(6066):     at android.test.db.TestDBMain$DB_Settings.addDBSettingsWithSQLCommand(TestDBMain.java:109)
07-20 01:00:53.516: ERROR/AndroidRuntime(6066):     at android.test.db.TestDBMain.onCreate(TestDBMain.java:35)
07-20 01:00:53.516: ERROR/AndroidRuntime(6066):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-20 01:00:53.516: ERROR/AndroidRuntime(6066):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

Answer 1

对于查询字符串，你必须输入'和'。试试这个

db.execSQL("UPDATE "+SETTINGS_TABLE_NAME
                +" set "+key+" = '"+value.toString()
                +"' where _id = 1;");

Answer 2

尝试此查询以进行更新..

 db.execSQL("UPDATE "+SETTINGS_TABLE_NAME
                +" set "+key+" = \""+value.toString()
                +"\" where _id = 1;");

Android：SQLiteDatabase - 没有这样的列

2 个答案: