安卓sqlite建表后只有三个字段

我在之后使用数据库时，发现只有前三个字段，INTRODUCT及以后的都没有，请问这是为什么
private static final String DATABASE_CREATE =

        "create table classname (_id integer primary key autoincrement,"
                + VIDEONAME +"varchar(20),"
                 +VIDEOADD +"varchar(20), "
                + INTRODUCT +"varchar(20), "
                + EXETIME +"varchar(20), "
                + IMGNAME +"vachar(20), "
                + TEACHERID +"varchar(20)"
                +")";
                                     db.execSQL(DATABASE_CREATE);