如何检查记录是否存在于数据库中

Question

I'm thinking how can I check if I my record exists running raw SQL queries. I tried to use is_null function but it doesn't work for me. So when I try to select wrong values and hitting the submit button it return me the 'Success' plain text in the browser.

public function readEmployeeRecords()
{
    $users = DB::select('select * from users where username = ?', [1]);

    if(is_null($users))
    {
        return ('Failed');  
    }
    else
    {
        return('Success');
    }
}

Form

<form class = "form-inline" role = "form" method = "post" action = "{{ route ('account.accountSearch') }}">

<div class = "form-group">

    <input type = "text" name = "search" class = "form-control" placeholder = "Employee username">

</div>

<button type = "submit" class = "btn btn-default">Search</button>
<input type = "hidden" name = "_token" value = "{{ Session::token() }}">

</form>

Answer 1

Use SELECT EXISTS( your subquery ) :

public function readEmployeeRecords()
{
    $users = DB::select('SELECT EXISTS(SELECT * FROM users WHERE username = ?)', [1]);

    if (!$users[0]) {
        return ('Failed');  
    }
    else {
        return('Success');
    }
}

My original answer was using COUNT(*) , which logically should have worked. However, I suspect th0at one "record" was always being returned, regardless of the actual count.

Answer 2

The Laravel 5.2 documentation says "The select method will always return an array of results." So you could use count() to see if there are any results in the array:

public function readEmployeeRecords()
{
    $users = DB::select('select * from users where username = ?', [1]);

    if ( ! count($users)) {
        return ('Failed');
    }

    return ('Success');
}

is_null() checks if a variable is NULL . An empty array is not equal to NULL

Answer 3

Try using

if(is_null($users) || $users = "") {