自动增量列必须是主键。

有不可能有一个自增塔和多列主键

Could anyone tell me what's wrong. Previously it worked perfectly for one table "books" but now I'm creating a new database with 3 tables and it's not executing. Here's the helper class.

public class DatabaseHelper extends SQLiteOpenHelper{

    private static final String DATABASE_NAME="MyDatabse1.db";
    public DatabaseHelper(Context context)
    {
        super(context,DATABASE_NAME,null,1);
    }
    public void onCreate(SQLiteDatabase db)
    {
        db.execSQL("CREATE TABLE userdetails (_id INTEGER AUTOINCREMENT, username TEXT UNIQUE, password TEXT, name TEXT, phonenumber TEXT, address TEXT, fine INTEGER, bookid INTEGER, PRIMARY KEY (_id, username, password));");
        db.execSQL("CREATE TABLE issue (_id INTEGER AUTOINCREMENT, book_id INTEGER UNIQUE, username TEXT, issue_date DATE, return_date DATE, PRIMARY KEY (_id, username, book_id));");
        db.execSQL("CREATE TABLE bookstable (_id INTEGER PRIMARY KEY AUTOINCREMENT, title TEXT, author TEXT, category TEXT, availability TEXT);");
}
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)     {

        db.execSQL("DROP TABLE IF EXISTS userdetails");
        db.execSQL("DROP TABLE IF EXISTS issue");
        db.execSQL("DROP TABLE IF EXISTS bookstable");

        onCreate(db);

        }

And here's the stack trace

07-18 12:47:22.686: E/SQLiteLog(3423): (1) near "AUTOINCREMENT": syntax error
07-18 12:47:22.916: E/AndroidRuntime(3423): FATAL EXCEPTION: main
07-18 12:47:22.916: E/AndroidRuntime(3423): java.lang.IllegalStateException:     Could not execute method of the activity

07-18 12:47:22.916: E/AndroidRuntime(3423): Caused by: android.database.sqlite.SQLiteException: near "AUTOINCREMENT": syntax error  (code 1): , while compiling: CREATE TABLE userdetails (_id INTEGER AUTOINCREMENT, username TEXT UNIQUE, password TEXT, name TEXT, phonenumber TEXT, address TEXT, fine INTEGER, bookid INTEGER, PRIMARY KEY (_id, username, password));
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1672)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at com.example.libraryplus.DatabaseHelper.onCreate(DatabaseHelper.java:26)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at com.example.libraryplus.DatabaseHelper.add_books(DatabaseHelper.java:53)
07-18 12:47:22.916: E/AndroidRuntime(3423):     at com.example.libraryplus.AddBooksActivity.addNewBooks(AddBooksActivity.java:42)

An AUTOINCREMENT column must be the PRIMARY KEY.

It is not possible to have an autoincrementing column and a multi-column primary key.