sql - Select data from columns in multiple tables with php and sqlite -

i creating login multiple tables. have checked answers here.

but can't seem understand how works? below php select statement

select export.uname exportname, export.pword exportpword,         import.uname importname, import.pword importpword,         lba.uname lbaname, lba.pword lbapword  exportname = '$username' , exportpword = '$password',        importname = '$username' , importpword = '$password'; 

but error:

warning: sqlite3::query(): unable prepare statement: 17, near ",": syntax error in c:\xampp\htdocs\xport\login.php on line 15

warning: sqlite3::querysingle(): unable prepare statement: 1, ambiguous column name: uname in c:\xampp\htdocs\xport\login.php on line 17 information incorrect

i don't know error coming because don't understand how select multiple tables.

if 1 table type:

select * table uname = '$username' , pword = '$password'; 

all asking how multiple tables. advance.