我正在尝试在我的应用中创建一个数据库。不幸的是，我在运行我的应用程序时遇到了一些麻烦。
DbHandler类：
package com.example.jarno.a49_savingdata;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
/**
* Created by jarno on 24-1-17.
*/
public class MyDbHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "products.db";
public static final String TABLE_PRODUCTS = "products";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_PRODUCTNAME = "productname";
public MyDbHandler(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String query = "CREATE TABLE " + TABLE_PRODUCTS + "(" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT " +
COLUMN_PRODUCTNAME + " TEXT " +
");";
db.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP_TABLE_IF_EXISTS" + TABLE_PRODUCTS);
onCreate(db);
}
public void addProduct(Products product) {
ContentValues values = new ContentValues();
values.put(COLUMN_PRODUCTNAME, product.get_productname());
SQLiteDatabase db = getWritableDatabase();
db.insert(TABLE_PRODUCTS, null, values);
db.close();
}
public void delProduct(String productName) {
SQLiteDatabase db = getWritableDatabase();
db.execSQL("DELETE FROM " + TABLE_PRODUCTS + " WHERE " + COLUMN_PRODUCTNAME + "=\"" + productName + "\";" );
}
public String databaseToString() {
String dbString = "";
SQLiteDatabase db = getWritableDatabase();
String query = "SELECT * FROM " + TABLE_PRODUCTS + " WHERE 1";
// Cursor point to a location in the results
Cursor c = db.rawQuery(query, null);
// Move to the first row in the results
c.moveToFirst();
while(!c.isAfterLast()) {
if(c.getString(c.getColumnIndex("productname")) != null) {
dbString += c.getString(c.getColumnIndex("productname"));
dbString += "\n";
}
}
db.close();
return dbString;
}
}
错误：
FATAL EXCEPTION: main
Process: com.example.jarno.a49_savingdata, PID: 4115
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.jarno.a49_savingdata/com.example.jarno.a49_savingdata.MainActivity}: android.database.sqlite.SQLiteException: near "productname": syntax error (code 1): , while compiling: CREATE TABLE products(_id INTEGER PRIMARY KEY AUTOINCREMENT productname TEXT ):
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: android.database.sqlite.SQLiteException: near "productname": syntax error (code 1): , while compiling: CREATE TABLE products(_id INTEGER PRIMARY KEY AUTOINCREMENT productname TEXT ):
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.executeSql(SQLiteDatabase.java:1677)
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1608)
at com.example.jarno.a49_savingdata.MyDbHandler.onCreate(MyDbHandler.java:31)
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:251)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
at com.example.jarno.a49_savingdata.MyDbHandler.databaseToString(MyDbHandler.java:55)
at com.example.jarno.a49_savingdata.MainActivity.printDatabase(MainActivity.java:40)
at com.example.jarno.a49_savingdata.MainActivity.onCreate(MainActivity.java:23)
at android.app.Activity.performCreate(Activity.java:6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
我认为此代码一定有问题，但我无法找到答案：
"CREATE TABLE " + TABLE_PRODUCTS + "(" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT " +
COLUMN_PRODUCTNAME + " TEXT " +
");";
答案 0 :(得分：4)
在宣布新列
时，在AUTOINCREMENT之后加上逗号
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +