使用PHP将LONGBLOB文件从一个表复制到另一个表

//SELECT DB
$con = mysqli_connect("localhost","root","","database");

//FETCH DATA FROM TABLE1
$check= mysqli_query($con, "select * from user_info_tbl where username = '$user_check' ") or die(mysqli_error($con));

$row = mysqli_fetch_array($check); 
$username = $row["username"];
$picture = $row["picture"]; //my way of getting the blob file to table1

$content = addslashes($_POST["content"]); //this is from an input tag

//INSERTING DATA TO TABLE2 INCLUDING THE BLOB FILE
$query1="INSERT INTO postings (prof_pic,user_name, content)
        VALUES ('$picture','$username','$content')";

This is my table1

|ID    |username     |    picture
+------+-------------+-----------------+
|1     |user1        | [BLOB -7.3 KiB] |
|2     |user2        | [BLOB -2.4 KiB] |
|3     |user3        | [BLOB -6.0 KiB] |

This is my table2

|ID    |prof_pic     | username  |  content
+------+-------------+-----------+-----------+
|1     |             | user1     |this is my post
|2     |             | user2     |hello world
|3     |             | user2     |lets go

But only the username and content are being inserted into the table2. I want to get the 'picture' on table1 to copy on 'prof_pic' on table2, where table1.username = table2.username

Can someone help me, getting the blob file to insert it to another table. Thanks in advance.

PS. Im just a beginner. Sorry for messy codes.