在table1列中获取值，列名是table2中的值

Question

I have two table, table2 has nameColumn that include name of table1 column like

table 1

id|check|status|...|
1 |abc  |1     |...|

table2

|nameColumn|...|
|check     |...|
|status    |...|

I want get value in table1 with column name is value in table2 like

    $sql="SELECT * FROM `table1` WHERE `id` = 1 ";
$result = mysqli_query($conn,$sql) or die (mysql_error ());
$rowTable = mysqli_fetch_array($result);

    $s = "SELECT * FROM table2";
$r = mysqli_query($conn,$s);
    while($row1 = mysqli_fetch_array($r)){
           $columnName = $row1['nameColumn'];
           $value = $rowTable["'".$columnName."'"]; // fail why?
           //$value = $rowTable['check']; // working? 
    }

I don't know why $value = $rowTable["'".$columnName."'"]; fail the error like

Notice: Undefined index: 'check' ... 

But if i using direct like $value = $rowTable['check']; // working why?

How to fix that thanks

Answer 1

its failing because your adding unnecessary ' char to it. try the code below

 $value = $rowTable[$columnName];