Android Studio SQLite 错误：列不正确（“没有这样的列：_id”）

问题描述 投票：0回答：1

我已经在 Android 应用程序中设置了 SQLite 数据库，但为了关注即时问题，将仅引用 

Users
表。在 
DatabaseContract
中，
Users
表定义为：

public final class DatabaseContract {
    private DatabaseContract() {}

    public static class Users implements BaseColumns {
        public static final String TABLE_NAME = "users";
        public static final String COLUMN_USER_ID = "_id";
        public static final String COLUMN_USER_NAME = "user_name";
        public static final String COLUMN_PASSWORD = "password";
        public static final String COLUMN_EMAIL = "email";
        public static final String COLUMN_DISPLAY_NAME = "display_name";
    }
    ...rest of tables in db
}

在

DatabaseHelper
课程中，这是
Users
表：

    private static final String SQL_CREATE_USERS_TABLE =
            "CREATE TABLE " + DatabaseContract.Users.TABLE_NAME + " (" +
                    DatabaseContract.Users.COLUMN_USER_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    DatabaseContract.Users.COLUMN_USER_NAME + " TEXT NOT NULL, " +
                    DatabaseContract.Users.COLUMN_PASSWORD + " TEXT NOT NULL, " +
                    DatabaseContract.Users.COLUMN_EMAIL + " TEXT, " +
                    DatabaseContract.Users.COLUMN_DISPLAY_NAME + " TEXT)";

在我的

AddUserActivity
类中运行此方法
addUserToDatabase(String name, String email, String password, String displayName)
，这似乎有效，但是我希望从
Users
表中获取自动生成的“id”，然后在此处检索“id”：

        // Check if the insertion was successful
        if (newRowId != -1) {
            // User was added successfully
            Toast.makeText(this, "User added successfully!", Toast.LENGTH_SHORT).show();

            // Get the user_id of the newly added user
            int user_id = getUserId(db, name);
      ...

方法如下

getUserId(db, name)
:

   private int getUserId(SQLiteDatabase db, String name) {
        int user_id = -1; // Default value if no user is found

        // Define the columns you want to retrieve
        String[] projection = {
                DatabaseContract.Users.COLUMN_USER_ID
        };

        // Define the selection based on the user name
        String selection = DatabaseContract.Users.COLUMN_USER_NAME + " = ?";
        String[] selectionArgs = { name };

        // Define the sort order (if needed)
        String sortOrder = null;

        Cursor cursor = db.query(
                DatabaseContract.Users.TABLE_NAME,
                projection,
                selection,
                selectionArgs,
                null,
                null,
                sortOrder
        );

        if (cursor.moveToFirst()) {
            // Get the user_id from the cursor
            int usersIdIndex = cursor.getColumnIndexOrThrow(DatabaseContract.Users.COLUMN_USER_ID);
            user_id = cursor.getInt(usersIdIndex);
        }

        // Close the cursor (don't close the database here)
        cursor.close();

        return user_id;
    }

然后我创建一个意图将此数据传递到 

WelcomeActivity
页面：

      ...
            // Create an Intent to navigate to WelcomeActivity
            Intent intent = new Intent(AddUserActivity.this, WelcomeActivity.class);

            int testNumber = 777;
            // Pass user data and user_id as extras in the Intent
            intent.putExtra("USER_ID", user_id);//testNumber
            intent.putExtra("USER_NAME", name);
            intent.putExtra("USER_EMAIL", email);
            intent.putExtra("USER_DISPLAY_NAME", displayName);

            // Start the WelcomeActivity
            startActivity(intent);

            // Close this activity
            finish();

此时程序崩溃并出现以下错误：

E/SQLiteLog: (1) no such column: _id in "SELECT _id FROM users WHERE user_name = ?"
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.enetapplications.songtracker, PID: 5937
    android.database.sqlite.SQLiteException: no such column: _id (code 1 SQLITE_ERROR[1]): , while compiling: SELECT _id FROM users WHERE user_name = ?
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1478)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:916)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:590)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:63)
        at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
        at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:46)
        at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:2088)
        at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1935)
        at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1806)
        at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1974)
        at com.enetapplications.songtracker.AddUserActivity.getUserId(AddUserActivity.java:124)
        at com.enetapplications.songtracker.AddUserActivity.addUserToDatabase(AddUserActivity.java:84)
        at com.enetapplications.songtracker.AddUserActivity.access$400(AddUserActivity.java:20)
        at com.enetapplications.songtracker.AddUserActivity$1.onClick(AddUserActivity.java:58)
        at android.view.View.performClick(View.java:7792)
        at android.widget.TextView.performClick(TextView.java:16112)
        at android.view.View.performClickInternal(View.java:7769)
        at android.view.View.access$3800(View.java:910)
        at android.view.View$PerformClick.run(View.java:30218)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:226)
        at android.os.Looper.loop(Looper.java:313)
        at android.app.ActivityThread.main(ActivityThread.java:8663)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:567)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)

我是 SQLite 新手，因此适应了 SQLite - 但对标准 SQL/MySQL 非常满意。我的倾向是将 

Users
表的键命名为 
user_id
，但是 SQLite 标准似乎是将表的键保留为 
_id

提前感谢您的审阅和评论！

最好的， 布莱恩

android sqlite android-sqlite
1个回答
0
投票

这是一个非常奇怪的问题 - 在应用程序开发的早期，在我的 

Users
表中，我将密钥设置为 
users_id
但后来更改了它（在 
DatabaseHelper
以及 
DatabaseContract
到 
user_id
。我保留了出现错误并且无法撤消原始数据库配置。最后我能够“看到”数据库元数据，意识到所有这些修改都没有执行任何操作：

   public void getTableMetadata(String tableName) {
        Log.d("SplashActivityZ", "IN: getTableMetadata(String tableName) - in DatabaseHelper.java, tableName=" + tableName + ")");
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery("PRAGMA table_info(" + tableName + ")", null);

        if (cursor != null) {
            try {
                if (cursor.moveToFirst()) {
                    do {
                        String columnName = cursor.getString(cursor.getColumnIndex("name"));
                        String columnType = cursor.getString(cursor.getColumnIndex("type"));

                        // Log the metadata for each column
                        Log.d("SplashActivityZ", "Column Name: " + columnName);
                        Log.d("SplashActivityZ", "Column Type: " + columnType);
                    } while (cursor.moveToNext());
                }
            } finally {
                cursor.close();
            }
        }
    }

输出始终如一：

 D  Column Name: users_id

其他尝试包括更改版本： 

private static final int DATABASE_VERSION = 3;
也没有做任何事情。

解决方案是更改数据库名称 - 只需添加“2”： 

private static final String DATABASE_NAME = "song_tracker2.db";

问题解决了。

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