一个PHP函数来处理不同的MySQLi select语句

Question

I have two MySQL tables with number of columns. The table structure is given below,

1.pictures
postedON
caption
imageName
thumbName
imageLocation
thumbLocation

2.Videos
postedOn
category
Link

I am using the folowing PHP function to fetch data from DB using a select command.

    function select($table){
    if($this->db_connection){
        $query = 'SELECT * FROM '. $table;

        $result = mysqli_query($this->db_connection,$query) or die($this->db_connection->error);
        //print_r($result);
        //echo "Affected rows: " . mysqli_affected_rows($this->db_connection);
        //var_dump($result);
        echo "<table>";
        echo "<tr>";
        echo "<th>Date Posted</th>";
        echo "<th>Category</th>";
        echo "<th>Link</th>";
        echo "</tr>";
        while($row = $result->fetch_assoc()){
            echo "<tr>";
            echo "<td>" . $row['postedOn'] . "</td>";
            echo "<td>".$row['category']. "</td>";
            echo "<td><a href=".$row['link'] .">" . $row['link'] . "</a></td>";
            echo "</tr>";
        }

            echo "</table>";
    }else{
        echo "db_connection is = " . $this->db_connection;
    }
}

}

The problem with this function as you can see, it can only serve only one table and not dynamic. Can someone please explain the way to dynamically fetch data from different table with different number of columns using only one PHP function? Thanks

Answer 1

Try using mysqli_fetch_fields()

<?php
function select($table){
  if($this->db_connection){
    $query = 'SELECT * FROM '. $table;

    $result = mysqli_query($this->db_connection,$query) or die($this->db_connection->error);
    $fieldinfo = mysqli_fetch_fields($result);
    echo "<table>";
    echo "<tr>";
    foreach ($fieldinfo as $val)
    {
        echo "<th>".$val->name."</th>";
    }
    echo "</tr>";
    while($row = $result->fetch_assoc()){
        echo "<tr>";
        foreach ($fieldinfo as $val)
        {
           echo "<td>" . $row[$val->orgname] . "</td>";
        }            
        echo "</tr>";
    }

    echo "</table>";
  }else{
     echo "db_connection is = " . $this->db_connection;
  }
}

Answer 2

It could be hard to explain given all the wrong premises you approach is based on, but I'll try.

First of all, you have to understand that a query like SELECT * FROM table has a very little use, next to none. Most of time you are always have some WHERE or at least LIMIT clause. So, such a function will have no use at all.

Next, you have to learn by heart that database interaction should never be intermixed with any output stuff like HTML.

Given these two premises above, your function should accept a fill qualified query as a parameter and return an array with data as a result.

For which array, in turn you can write a helper function to display its contents in the form of HTML table.

But again, such a generalized output function will be of little use as well, because, as you can see from your own example, different fields will need different formatting. So it's better to write output each time by hand.