Question

  private static final String MINDMAPS_TABLE_CREATE =
        "create table mindmaps (_id integer primary key autoincrement, "
                + "title text not null);";

  private static final String BUBBLES_TABLE_CREATE =
    "create table bubbles (_id integer primary key autoincrement, "
    + "title text not null), " +
            "_bmid integer, " +
            " FOREIGN KEY (_bmid) REFERENCES mindmaps (_id))";


private static class DatabaseHelper extends SQLiteOpenHelper {

    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL(MINDMAPS_TABLE_CREATE);
        db.execSQL(BUBBLES_TABLE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS bubbles");
        db.execSQL("DROP TABLE IF EXISTS mindmaps");
        onCreate(db);
    }
}

我得到如下例外：

 Caused by: android.database.sqlite.SQLiteException: near ",": syntax error (code 1): , while compiling: create table bubbles (_id integer primary key autoincrement, title text not null), _bmid integer,  FOREIGN KEY (_bmid) REFERENCES mindmaps (_id))
            at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)

声明有什么问题？

Answer 1

您在create table语句中有一个多余的结束语：

create table bubbles (_id integer primary key autoincrement,
    title text not null), 
-----------------------^
    bmid integer, 
    FOREIGN KEY (_bmid) REFERENCES mindmaps (_id))

如果删除它，代码应该有效。

此外，auto_increment有一个下划线。

Here是一个带有工作代码的SQL小提琴。

create table mindmaps (
    _id integer primary key auto_increment, 
    title text not null
);

create table bubbles (_id integer primary key auto_increment,
    title text not null,
    _bmid integer,
    FOREIGN KEY (_bmid) REFERENCES mindmaps (_id)
);

无法使用外键创建表

1 个答案: