从另一个表插入一个表并在一个 SQL 代码中从变量添加值

Question

i am using INSERT INTO SELECT Statement Syntax to insert values from another table into my main table in my php project

$student_id=1; // dummy id set in a variable
include 'conndb.php';
$sql = "INSERT INTO `student_resulttbl` ( subject_name,)\n"

        . "SELECT subject,\n"

        . "FROM `subjecttbl`\n"

        . "WHERE  subject_class ='$class' AND subject_session = '2020/2021'";

It worked well but my issue is how to insert variable $student_id along with this on student_resulttbl. pls note $student_id is not coming from subjecttbl. Its set already. Thank you

Answer 1

do you mean something like this?

$student_id=1; // dummy id set in a variable
include 'conndb.php';
$sql = "INSERT INTO `student_resulttbl` ( student_id, subject_name,)\n"

        . "SELECT " . mysqli_real_escape_string($connection, $Student_id) . ", subject\n"

        . "FROM `subjecttbl`\n"

        . "WHERE  subject_class ='$class' AND subject_session = '2020/2021'";

but have a look at prepared statements.

Is there a reason why you use newlines in SQL-Statements?

Answer 2

If you want to INSERT $student_id to student_resulttbl table you should do query like this:

INSERT INTO `student_resulttbl` ( subject_name, student_id ) VALUES ( 
(    SELECT subject FROM `subjecttbl` 
     WHERE  subject_class ='$class' 
     AND subject_session = '2020/2021'
),
$student_id);

The summary code:

$student_id=1; // dummy id set in a variable
include 'conndb.php';
$sql = "INSERT INTO `student_resulttbl` ( subject_name, student_id ) VALUES (" 
. "(SELECT subject FROM `subjecttbl` "
. "WHERE  subject_class ='$class' "
. "AND subject_session = '2020/2021'"
. "), $student_id)";

You can INSERT multiple columns with INSERT INTO command. More information there: w3schools.com/sql/sql_insert_into_select.asp or https://www.w3schools.com/sql/sql_insert.asp or https://www.dofactory.com/sql/insert