Php 在laravel上使用带条件的insert

我想在“ta”和“tb”int列中插入值，并附带一些条件。我有这个控制器

public function save()
{
$book = new Book;

$ta = DB::select('SELECT MAX(ta) from book');
if ($ta == 0) { 
        DB :: insert('insert into book (ta, tb) values (?, ?)', array(1, 1));
    }else{
        $tb = DB :: select('select max(tb) from book where ta = ?', array('$ta'));
        if ($tb <= 20) {
            DB :: insert('insert into book (ta, tb) values (ta=?, tb=?)', array('$ta', '$tb' + 1));
        }else{
            DB :: insert('insert into book (ta, tb) values (ta=?, tb=?)', array('$ta' + 1, 1));
        }
    }
$book->ta = $ta;
$book->tb = $tb;
$book->save();
}

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我如何解决这个问题？

它插入两次的原因是您创建了一个DB:：insert，并使用$book->save创建了一本新书

这应该更好地发挥作用：

$book = new Book;
$ta = DB::table('book')->selectRaw('MAX(ta) AS ta')->first()->ta;
if($ta == 0){
    $book->ta = 1;
    $book->tb = 1;
}
else {
    $tb = DB::table('book')->selectRaw('MAX(tb) AS tb')
            ->where('ta', $ta)->first()->tb;
    if($tb <= 20){
        $book->ta = $ta;
        $book->tb = $tb + 1;
    }
    else {
        $book->ta = $ta + 1;
        $book->tb = 1;
    }
}
$book->save();

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@lukasgeiter我在该控制器中编写了条件，结果是插入两次，列为0，然后请显示您拥有的确切代码。谢谢