我在Android应用中的数据库有问题。这是一些代码：
private static final String QUESTIONS_TABLE = "questions";
/* questions keys */
public static final String KEY_ROWID = "_id";
public static final String KEY_TYPE = "type";
public static final String KEY_CONTENT = "content";
public static final String KEY_A = "answerA";
public static final String KEY_B = "answerB";
public static final String KEY_C = "answerC";
public static final String KEY_D = "answerD";
private static final String QUESTIONS_TABLE_CREATE =
"create table "+ QUESTIONS_TABLE +" (" + KEY_ROWID + " integer primary key …