无法查询 Android 中的数据库
Unable to query database in Android
我试图制作一个购物应用程序的购物车，我首先查询一个购物车元素，然后从购物车的 ID 中，列表元素通过查询另一个元素找到与产品相关的相应元数据 table 包含产品信息。我能够在显示 "menu" 的同时 成功查询产品列表 并尝试将相同的代码应用于购物车。然而它告诉我列“_id”不存在。我坚持了一段时间。
You can find the entire project on GitHub
这里是相关文件的重要部分
YourCart.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_your_cart);
ContentValues values = new ContentValues();
values.put(CartContract.CartEntry._ID, 2);
values.put(CartContract.CartEntry.COLUMN_NAME_ORDERED_QUANTITY, 37);
getContentResolver().insert(CartContract.CartEntry.CONTENT_URI, values);
String[] projection = {
CartContract.CartEntry._ID,
CartContract.CartEntry.COLUMN_NAME_ORDERED_QUANTITY
};
//gets the entire cart
cart = getContentResolver().query(CartContract.CartEntry.CONTENT_URI, projection, null, null, null);
ListView cartList = findViewById(R.id.CartListView);
cartList.setAdapter(new cartAdapter(YourCart.this, cart));
}
// Following is part of cartAdapter
@Override
public void bindView(View view, Context context, Cursor cart) {
prodName = view.findViewById(R.id.cartListElementProductNameTextView);
prodPrice = view.findViewById(R.id.cartListElementProductPriceTextView);
//Projection is just the name of the columns we would like to receive
String[] projection = {
ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_THUMBNAIL,
ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_NAME,
ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_PRICE
};
Integer ui = cart.getInt(cart.getColumnIndexOrThrow(CartContract.CartEntry._ID));
String[] hoho = {ui.toString()};
Cursor productCursor = getContentResolver().query(ProductListContract.ProductEntry.CONTENT_URI, projection, ProductListContract.ProductEntry._ID, hoho, null);
prodName.setText(productCursor.getInt(productCursor.getColumnIndexOrThrow(ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_NAME)));
ui = productCursor.getInt(productCursor.getColumnIndexOrThrow(ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_PRICE));
prodPrice.setText(ui.toString());
productCursor.close();
}
我很确定在创建 table 时也会创建该列，从数据库助手
的摘录中可以看出
public static final String SQL_CREATE_ENTRIES =
"CREATE TABLE " + TABLE_NAME + " ( " +
_ID + " INTEGER NON NULL, " +
COLUMN_NAME_ORDERED_QUANTITY + " INTEGER)";
最后是崩溃日志。一旦启动 YourCart activity，应用程序就会崩溃
03-16 09:50:30.987 11672-11672/com.example.tanmay.shoppingapp E/SQLiteLog: (1) table cart has no column named _id
03-16 09:50:30.991 11672-11672/com.example.tanmay.shoppingapp E/SQLiteDatabase: Error inserting quantity=37 _id=2
android.database.sqlite.SQLiteException: table cart has no column named _id (code 1): , while compiling: INSERT INTO cart(quantity,_id) VALUES (?,?)
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.insertWithOnConflict(SQLiteDatabase.java:1472)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1343)
at com.example.tanmay.shoppingapp.DataSet.DataProvider.insertCart(DataProvider.java:169)
at com.example.tanmay.shoppingapp.DataSet.DataProvider.insert(DataProvider.java:155)
at android.content.ContentProvider$Transport.insert(ContentProvider.java:264)
at android.content.ContentResolver.insert(ContentResolver.java:1279)
at com.example.tanmay.shoppingapp.YourCart.onCreate(YourCart.java:34)
at android.app.Activity.performCreate(Activity.java:6684)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2652)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2766)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1507)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6236)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
03-16 09:50:30.991 11672-11672/com.example.tanmay.shoppingapp E/com.whatever.tag: Failed to insert row for content://com.example.tanmay.shoppingapp/cart
03-16 09:50:30.992 11672-11672/com.example.tanmay.shoppingapp E/SQLiteLog: (1) no such column: _id
03-16 09:50:30.994 11672-11672/com.example.tanmay.shoppingapp D/AndroidRuntime: Shutting down VM
03-16 09:50:30.996 11672-11672/com.example.tanmay.shoppingapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tanmay.shoppingapp, PID: 11672
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tanmay.shoppingapp/com.example.tanmay.shoppingapp.YourCart}: android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, quantity FROM cart
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2699)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2766)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1507)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6236)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
Caused by: android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, quantity FROM cart
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1318)
at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1165)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1036)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1204)
at com.example.tanmay.shoppingapp.DataSet.DataProvider.query(DataProvider.java:92)
at android.content.ContentProvider.query(ContentProvider.java:1020)
at android.content.ContentProvider$Transport.query(ContentProvider.java:239)
at android.content.ContentResolver.query(ContentResolver.java:534)
at android.content.ContentResolver.query(ContentResolver.java:475)
at com.example.tanmay.shoppingapp.YourCart.onCreate(YourCart.java:44)
at android.app.Activity.performCreate(Activity.java:6684)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2652)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2766)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1507)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6236)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
尝试用这个替换您的创建 SQL_CREATE_ENTRIES 语句，
public static final String SQL_CREATE_ENTRIES =
"CREATE TABLE " + TABLE_NAME + " ( " +
_ID + " INTEGER NOT NULL, " +
COLUMN_NAME_ORDERED_QUANTITY + " INTEGER)";
您的查询在 _ID 列中包含无效关键字，即 "NON"。
出于某种原因，table 不包含名为 _id 的列。但是，这不是因为 SQL，即使 SQL 可能不会按照您的意愿进行。
更具体地说，使用 INTEGER NON（而不是 NOT）NULL 将不会添加 NOT NULL 约束，它会给列一个 column_type of INTEGER NON，因为它包含 INT，所以等同于 INTEGER.
的 column-type（亲和力）
作为一个例子（这利用了 logDatabaseInfo ）其中 SQL 作为 :-
CREATE TABLE cart (_ID INTEGER NON NULL, quantity INTEGER)
显示：-
D/SQLITE_CSU: DatabaseList Row 1 Name=main File=/data/data/soupd.so49313202updatefailed/databases/mydb
D/SQLITE_CSU: Database Version = 1
D/SQLITE_CSU: Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT)
D/SQLITE_CSU: Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
D/SQLITE_CSU: Table Name = cart Created Using = CREATE TABLE cart (_ID INTEGER NON NULL, quantity INTEGER)
D/SQLITE_CSU: Table = cart ColumnName = _ID ColumnType = INTEGER NON Default Value = null PRIMARY KEY SEQUENCE = 0
D/SQLITE_CSU: Table = cart ColumnName = quantity ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
Table = cart ColumnName = _ID ColumnType = INTEGER NON 默认值 = null 是相关信息。
SQL 应该是：-
CREATE TABLE cart (_ID INTEGER NOT NULL, quantity INTEGER)
- Note normally _id/_ID is used for a column that holds a unique identifier that is automatically generated by SQLite, and thus
typically you would have
_ID INTEGER PRIMARY KEY for the column
definition. Coding this and not providing a value for the _id will
result in the unique identifier being generated by SQLite (typically
1,2,3,4.....).
- Note I haven't shown this in the SQL below because you would need to look at inserting without the id.
可能真正的问题
真正的问题在别处，但很可能是由于没有调用 DatabaseHelper 的 onCreate 方法。由于数据库存在，它可能被调用过一次。所以最有可能的问题是 table 结构已更改但数据库尚未删除。
更具体地说，onCreate 方法仅在创建数据库时（自动）调用一次。
可能的修复
可能的解决方法是删除数据库，然后重新运行应用程序。
- 您可以通过删除应用程序的数据来删除数据库
- 或通过卸载应用程序。
- 我建议如上所示更改 SQL。
我试图制作一个购物应用程序的购物车，我首先查询一个购物车元素，然后从购物车的 ID 中，列表元素通过查询另一个元素找到与产品相关的相应元数据 table 包含产品信息。我能够在显示 "menu" 的同时 成功查询产品列表 并尝试将相同的代码应用于购物车。然而它告诉我列“_id”不存在。我坚持了一段时间。
You can find the entire project on GitHub
这里是相关文件的重要部分
YourCart.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_your_cart);
ContentValues values = new ContentValues();
values.put(CartContract.CartEntry._ID, 2);
values.put(CartContract.CartEntry.COLUMN_NAME_ORDERED_QUANTITY, 37);
getContentResolver().insert(CartContract.CartEntry.CONTENT_URI, values);
String[] projection = {
CartContract.CartEntry._ID,
CartContract.CartEntry.COLUMN_NAME_ORDERED_QUANTITY
};
//gets the entire cart
cart = getContentResolver().query(CartContract.CartEntry.CONTENT_URI, projection, null, null, null);
ListView cartList = findViewById(R.id.CartListView);
cartList.setAdapter(new cartAdapter(YourCart.this, cart));
}
// Following is part of cartAdapter
@Override
public void bindView(View view, Context context, Cursor cart) {
prodName = view.findViewById(R.id.cartListElementProductNameTextView);
prodPrice = view.findViewById(R.id.cartListElementProductPriceTextView);
//Projection is just the name of the columns we would like to receive
String[] projection = {
ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_THUMBNAIL,
ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_NAME,
ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_PRICE
};
Integer ui = cart.getInt(cart.getColumnIndexOrThrow(CartContract.CartEntry._ID));
String[] hoho = {ui.toString()};
Cursor productCursor = getContentResolver().query(ProductListContract.ProductEntry.CONTENT_URI, projection, ProductListContract.ProductEntry._ID, hoho, null);
prodName.setText(productCursor.getInt(productCursor.getColumnIndexOrThrow(ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_NAME)));
ui = productCursor.getInt(productCursor.getColumnIndexOrThrow(ProductListContract.ProductEntry.COLUMN_NAME_PRODUCT_PRICE));
prodPrice.setText(ui.toString());
productCursor.close();
}
我很确定在创建 table 时也会创建该列，从数据库助手
的摘录中可以看出 public static final String SQL_CREATE_ENTRIES =
"CREATE TABLE " + TABLE_NAME + " ( " +
_ID + " INTEGER NON NULL, " +
COLUMN_NAME_ORDERED_QUANTITY + " INTEGER)";
最后是崩溃日志。一旦启动 YourCart activity，应用程序就会崩溃
03-16 09:50:30.987 11672-11672/com.example.tanmay.shoppingapp E/SQLiteLog: (1) table cart has no column named _id
03-16 09:50:30.991 11672-11672/com.example.tanmay.shoppingapp E/SQLiteDatabase: Error inserting quantity=37 _id=2
android.database.sqlite.SQLiteException: table cart has no column named _id (code 1): , while compiling: INSERT INTO cart(quantity,_id) VALUES (?,?)
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.insertWithOnConflict(SQLiteDatabase.java:1472)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1343)
at com.example.tanmay.shoppingapp.DataSet.DataProvider.insertCart(DataProvider.java:169)
at com.example.tanmay.shoppingapp.DataSet.DataProvider.insert(DataProvider.java:155)
at android.content.ContentProvider$Transport.insert(ContentProvider.java:264)
at android.content.ContentResolver.insert(ContentResolver.java:1279)
at com.example.tanmay.shoppingapp.YourCart.onCreate(YourCart.java:34)
at android.app.Activity.performCreate(Activity.java:6684)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2652)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2766)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1507)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6236)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
03-16 09:50:30.991 11672-11672/com.example.tanmay.shoppingapp E/com.whatever.tag: Failed to insert row for content://com.example.tanmay.shoppingapp/cart
03-16 09:50:30.992 11672-11672/com.example.tanmay.shoppingapp E/SQLiteLog: (1) no such column: _id
03-16 09:50:30.994 11672-11672/com.example.tanmay.shoppingapp D/AndroidRuntime: Shutting down VM
03-16 09:50:30.996 11672-11672/com.example.tanmay.shoppingapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tanmay.shoppingapp, PID: 11672
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tanmay.shoppingapp/com.example.tanmay.shoppingapp.YourCart}: android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, quantity FROM cart
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2699)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2766)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1507)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6236)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
Caused by: android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, quantity FROM cart
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1318)
at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1165)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1036)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1204)
at com.example.tanmay.shoppingapp.DataSet.DataProvider.query(DataProvider.java:92)
at android.content.ContentProvider.query(ContentProvider.java:1020)
at android.content.ContentProvider$Transport.query(ContentProvider.java:239)
at android.content.ContentResolver.query(ContentResolver.java:534)
at android.content.ContentResolver.query(ContentResolver.java:475)
at com.example.tanmay.shoppingapp.YourCart.onCreate(YourCart.java:44)
at android.app.Activity.performCreate(Activity.java:6684)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2652)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2766)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1507)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6236)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
尝试用这个替换您的创建 SQL_CREATE_ENTRIES 语句，
public static final String SQL_CREATE_ENTRIES =
"CREATE TABLE " + TABLE_NAME + " ( " +
_ID + " INTEGER NOT NULL, " +
COLUMN_NAME_ORDERED_QUANTITY + " INTEGER)";
您的查询在 _ID 列中包含无效关键字，即 "NON"。
出于某种原因，table 不包含名为 _id 的列。但是，这不是因为 SQL，即使 SQL 可能不会按照您的意愿进行。
更具体地说，使用 INTEGER NON（而不是 NOT）NULL 将不会添加 NOT NULL 约束，它会给列一个 column_type of INTEGER NON，因为它包含 INT，所以等同于 INTEGER.
作为一个例子（这利用了 logDatabaseInfo
CREATE TABLE cart (_ID INTEGER NON NULL, quantity INTEGER)
显示：-
D/SQLITE_CSU: DatabaseList Row 1 Name=main File=/data/data/soupd.so49313202updatefailed/databases/mydb
D/SQLITE_CSU: Database Version = 1
D/SQLITE_CSU: Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT)
D/SQLITE_CSU: Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
D/SQLITE_CSU: Table Name = cart Created Using = CREATE TABLE cart (_ID INTEGER NON NULL, quantity INTEGER)
D/SQLITE_CSU: Table = cart ColumnName = _ID ColumnType = INTEGER NON Default Value = null PRIMARY KEY SEQUENCE = 0
D/SQLITE_CSU: Table = cart ColumnName = quantity ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
Table = cart ColumnName = _ID ColumnType = INTEGER NON 默认值 = null 是相关信息。
SQL 应该是：-
CREATE TABLE cart (_ID INTEGER NOT NULL, quantity INTEGER)
- Note normally _id/_ID is used for a column that holds a unique identifier that is automatically generated by SQLite, and thus typically you would have
_ID INTEGER PRIMARY KEYfor the column definition. Coding this and not providing a value for the _id will result in the unique identifier being generated by SQLite (typically 1,2,3,4.....).- Note I haven't shown this in the SQL below because you would need to look at inserting without the id.
可能真正的问题
真正的问题在别处，但很可能是由于没有调用 DatabaseHelper 的 onCreate 方法。由于数据库存在，它可能被调用过一次。所以最有可能的问题是 table 结构已更改但数据库尚未删除。
更具体地说，onCreate 方法仅在创建数据库时（自动）调用一次。
可能的修复
可能的解决方法是删除数据库，然后重新运行应用程序。 - 您可以通过删除应用程序的数据来删除数据库 - 或通过卸载应用程序。 - 我建议如上所示更改 SQL。