语法错误或访问冲突：1064您在alter table中的SQL语法中有错误

Question

I am trying to alter the auto_increment by laravel stament function and it is giving the error.

The complete error message displaying is SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '?' at line 1 (SQL: alter table bills AUTO_INCREMENT=9)

if($quantity[$i]>$qtny)
{
    Bills::where('id','=',$invoice_no)->delete();
    DB::enableQueryLog();
        DB::statement('alter table `bills` AUTO_INCREMENT=?',array('invoice_no'=>$invoice_no));
    dd(DB::getQueryLog());
    //return "<script>alert('Quantity is not available for product ".$item_name[$i]."');location.href='/create';</script>";
}

Answer 1

Variable placeholders are not allowed everywhere:

Within the statement, ? characters can be used as parameter markers to indicate where data values are to be bound to the query later when you execute it.

alter table requires a constant here, eg you could not use something like alter table bills AUTO_INCREMENT = (select max(id) from bills) . Generally, everywhere you could do this, you are allowed to use placeholders (with some exceptions like limit , but those are then mentioned in the documentation ).

So in this case you have to use the value directly:

DB::statement('alter table `bills` AUTO_INCREMENT = '.$invoice_no)

Answer 2

Variable Placeholder is not allowed here. So. I have done by this way,

DB::statement('alter table `bills` AUTO_INCREMENT = '.$invoice_no);

Answer 3

You can write the laravel query in two diffrent way you can tokenize variable

1) First method

if($quantity[$i]>$qtny)
{
    Bills::where('id','=',$invoice_no)->delete();
    DB::enableQueryLog();
        DB::statement('alter table `bills` AUTO_INCREMENT=:invoice_no',array('invoice_no'=>$invoice_no));
    dd(DB::getQueryLog());
    //return "<script>alert('Quantity is not available for product ".$item_name[$i]."');location.href='/create';</script>";
}

2) Second method

if($quantity[$i]>$qtny)
{
    Bills::where('id','=',$invoice_no)->delete();
    DB::enableQueryLog();
        DB::statement('alter table `bills` AUTO_INCREMENT=?',[$invoice_no]);
    dd(DB::getQueryLog());
    //return "<script>alert('Quantity is not available for product ".$item_name[$i]."');location.href='/create';</script>";
}

You can also write query below but your query will be wide open for sql injection.

DB::statement('alter table bills AUTO_INCREMENT = '.$invoice_no);