Android表创建失败(接近"自动增量":语法错误)？

Question

 public static final String MYDATABASE_NAME = "MY_DATABASE";
 public static final String MYDATABASE_TABLE = "MY_TABLE";
 public static final String MYDATABASE_TABLE2 = "MY_TABLE2";
 public static final int MYDATABASE_VERSION = 1;
 public static final String KEY_ID = "_id";
 public static final String KEY_ID2 = "_id2";
 public static final String KEY_CONTENT1 = "Content1";
 public static final String KEY_CONTENT2 = "Content2";
 public static final String KEY_CONTENT3 = "Content3";

 //create table MY_DATABASE (ID integer primary key, Content text not null);
 private static final String SCRIPT_CREATE_DATABASE = "create table " + MYDATABASE_TABLE + " (" 
                                                        +KEY_ID + " integer primary key autoincrement, " 
                                                        + KEY_CONTENT1 + " text not null);";

 private static final String SCRIPT_CREATE_DATABASE2 = "create table " + MYDATABASE_TABLE2 + " (" 
                                                        + KEY_ID2 + " integer autoincrement, " 
                                                        + KEY_CONTENT2 + " text not null, " 
                                                        + KEY_CONTENT3 + " text not null, "
                                                        + " FOREIGN KEY ("+KEY_ID2+") REFERENCES "+MYDATABASE_TABLE+" ("+KEY_ID+"));";

我无法找出出现以下错误,请帮帮我谢谢.

09-29 13:41:19.760:ERROR /数据库(334):在准备'create table MY_TABLE2时,在0x218df0上失败1(接近"自动递增":语法错误)(_id2整数自动递增,Content2文本不为null,Content3文本不为null, FOREIGN KEY(_id2)REFERENCES MY_TABLE(_id));'.

09-29 13:41:19.770:DEBUG/AndroidRuntime(334):关闭VM

09-29 13:41:19.770:WARN/dalvikvm(334):threadid = 1:线程退出未捕获异常(组= 0x4001d800)

09-29 13:41:19.791:ERROR/AndroidRuntime(334):致命异常:主要

09-29 13:41:19.791:ERROR/AndroidRuntime(334):java.lang.RuntimeException:无法启动活动ComponentInfo {sep.com/sep.com.SepActivity}:android.database.sqlite.SQLiteException:near"autoincrement ":语法错误:创建表MY_TABLE2(_id2整数自动增量,Content2文本不为空,Content3文本不为空,FOREIGN KEY(_id2)REFERENCES MY_TABLE(_id));

Answer 1

简而言之:SQLite中In SQLite a column declared INTEGER PRIMARY KEY will autoincrement.没有autoincrement关键字,这就是您收到错误的原因.

您可以在SQLite FAQ上找到更多信息.

编辑:只是写integer primary key它就足够了.SQLite会自动递增你的ids.

编辑2:您的onUpgrade()方法应如下所示:

  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (newVersion > oldVersion) {
            Log.w("MyAppTag","Updating database from version " + oldVersion + " to "
                    + newVersion + " .Existing data will be lost.");
            db.execSQL("DROP TABLE IF EXISTS " + MY_TABLE);
            db.execSQL("DROP TABLE IF EXISTS " + MY_TABLE2);
            onCreate(db);
        }

Answer 2

这个:

+ KEY_ID2 + " integer autoincrement, " 

应该这样:

+ KEY_ID2 + " integer primary key autoincrement, " 

如果您按照语法图表进行操作,CREATE TABLE您将会看到autoincrement只有之后才会出现primary key.

如果你想_id2成为一个外键,那么你根本不希望它是自动增量.