単純なwhere
$query->where('col1', $val1)
$query->where('col1', '<>', $val1)
where でAND
$query->where('col1', $val1)->where('col2', $val2)
where でOR
$query->where('col1', $val1)->orWhere('col2', $val2)
where で複数値
$query->whereIn('col1', array($val1,$val2))
$query->whereNotIn('col1', array($val1,$val2))
where でNull
$query->whereNull('col1')
$query->whereNotNull('col1')
where で(A AND B) Or (C or D)など
$query->where(function($query) use($val1,$val2){
$query->where('col1',$val1)
->where('col2',$val2)
})
->orWhere(function($query) use($val3,$val4){
$query->where('col3',$val3)
->where('col4',$val4)
})