检查是否存在关于其值的特定行

Question

I want to check if a string exists in a row in a specific table, i have had no luck in doing this but i was able to gain an understanding on how $query->num_rows(); works and i thought i would have to do something like.

The code i tried below i thought will check if the d009 value exists in the dept_no row and if their are no rows with the value d009 then it should produce an error message.

When i run the code it does not echo any message

$this->db->where('dept_no', 'd009');

$query = $this->db->get('dept_manager');
if($query->num_rows()==0)
{
    echo "true";            
}
else
{
    echo "false";
}

dept_manager table

d009 a
d008 b
d007 c  

Answer 1

I think if.. else should be opposite of what you have specified

if($query->num_rows()==0)
{
    echo "false";            
}
else
{
    echo "true";
}

I mean if num_rows() returns zero rows means value not present in the row....