Multiple Queries only the last one executing - php

Question

I have this code below;
$sql = "SELECT * FROM tbl1 where id_no = '$id_no'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$new = $row['full_name'];
header("location:new.php?msg=ID Number $id is already
Registered");
}
} else {
$created = date('jS \ F Y h:i:s A');
$tr_no = 'TR_'.rand(10000,99999).'/'.date(Y).'';
include '../db_config/connection.php';
//update tables
$sql = "INSERT INTO tbl2 (id,vehicle_id,policy_id,insured_by,insurance_co,value_insured,start_date,end_date,created)VALUES ('$tr_no','$reg_no','$p_id','$user_index','$co_id','$value_insured','$start_date','$end_date','$created')" ;
$sql = "UPDATE tbl1 SET updated='1' WHERE item_id = '$reg_no'";
$sql = "INSERT INTO tbl3 (doc_number,value,date,reg_no) VALUES('$tr_no','-$value_insured','$created','$reg_no'";
if ($conn->query($sql) === TRUE) {
header("location:new_insurance.php?message=ENTRIES SUCCESSFULLY POSTED");
} else {
$error = $conn->error;
header("location:new_client.php?err=$error");
}
$conn->close();
}
$conn->close();
?>
The last bit that contains the insert and update queries is where am having the problem. Rather than executing all the three queries, only the last one is executed. What modifications should i include?

Answer 1

First Change these statements (concatenates the $sql variable and add semicolon ';' at end of each statements.)
$sql = "INSERT INTO tbl2 (id,vehicle_id,policy_id,insured_by,insurance_co,value_insured,start_date,end_date,created) VALUES ('$tr_no','$reg_no','$p_id','$user_index','$co_id','$value_insured','$start_date','$end_date','$created');" ;
$sql .= "UPDATE tbl1 SET updated='1' WHERE item_id = '$reg_no';";
$sql .= "INSERT INTO tbl3 (doc_number,value,date,reg_no) VALUES('$tr_no','-$value_insured','$created','$reg_no');";
Now finally execute multiple queries by mysqli_multi_query()
if (mysqli_multi_query($con,$sql)) { //con is your connection
header("location:new_insurance.......