android - Sqlite, join table: ambiguous column error -

i have database , executing query:

select *         exams left outer join test on test.texamid = exams.eid               left outer join test on users.userid = test.tuserid 

but got error ambiguous column name main.test.tid. have ever seen before? please me figure out happen.

my database below:

    create table [exams] (       [eid] integer not null primary key,        [etype] integer not null,        [elevel] integer not null,        [etime] integer,        [enote] char);       create table [users] (       [userid] text not null,        [userpassword] text not null);      create unique index [userid] on [users] ([userid]);       create table [test] (       [tid] integer not null primary key autoincrement,        [tuserid] text not null references [users]([userid]),        [texamid] integer not null references [exams]([eid]),        [tdate] date not null,        [tscore] integer not null,        [tnote] char not null); 

you introduced typo ... wanted have:

select *  exams left outer join test on test.texamid = exams.eid        left outer join users on users.userid = test.tuserid