How to select values from two tables in mysql prepared statements

Question

For adding database I am using PhpMyAdmin in Xampp server. I have created two tables and each table contains different rows. I am trying to select values from two tables at the same time in php. The following code works fine

    $gi1=2;

    $stmt2=$this->con->prepare(" SELECT qwer  FROM table1  WHERE nmnm=?;");
    $stmt2->bind_param("i",$gi1);
    $stmt2->execute();
    $stmt2->bind_result($var1);
    $stmt2->fetch();

    $gi2=23;

    $stmt2=$this->con->prepare(" SELECT qwer2  FROM table2  WHERE nmnm2=?;");
    $stmt2->bind_param("i",$gi2);
    $stmt2->execute();
    $stmt2->bind_result($var2);
    $stmt2->fetch();

But it takes too much time so I decided it to select in one statement.

$gi2=23;$gi1=2;

    $stmt2=$this->con->prepare(" SELECT qwer2,qwer1  FROM table2,table1  WHERE nmnm2=? or nmnm=?;");
    $stmt2->bind_param("ii",$gi2,$gi1);
    $stmt2->execute();
    $stmt2->bind_result($var2,$var1);
    $stmt2->fetch();

And it shows a fatal error.So how can I select values from two tables in one statement?

Answer 1

if the tables do not have any link columns you can try with UNION

SELECT qwer  FROM table1  WHERE nmnm=?
union
(SELECT qwer2 as qwer  FROM table2  WHERE nmnm2=?)