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);