MySQL SELECT所有列，但将空列或空列替换为某些默认值

Question

Currently I have PHP code like this (CodeIgniter):

$detail = $this->db->query("SELECT * FROM tm_survei WHERE ID_SURVEI=5")->row_array();
foreach($detail as &$val){
    if (!!!$val) $val = '-'; //replace all the empty or null values with "-"
}

It solved the problem, but I wonder is it possible to do that in MySQL query itself without that PHP foreach eg SELECT IFNULL(*,'-') <original-column-name> FROM tm_survei ?

Answer 1

IFNULL is really good enough like you suggested, just use SELECT with list of fields to show, not *. Usually, it's ok.

$detail = $this->db->query("SELECT id, title, IFNULL(column_name1, '-'), IFNULL(column_name2, '-') as aliasname FROM tm_survei WHERE ID_SURVEI=5")->row_array();
foreach($detail as &$val){
    $val; 
}