select insert into not working - php

Question

I am trying to insert a number of ids into a new table. The list of ids is taken from another table.
My Code:
$stmt = $con->prepare('DROP TABLE tblname;
CREATE TABLE tblname (
id BIGINT
);
INSERT INTO tblname (id)
SELECT tablename2.colname
FROM tablename2
WHERE (col1 = "value" AND col2 = "value")');
$stmt->execute();
I create and dump the table because its part of an update script.
(Is there a better way to do that than dump/create?)
The script needs the current list of ids and I am trying to get create a table with those ids. What happens is, whenever I run the code (using putty) it returns "0" and the table remains empty.
What did I do wrong?
Any general help/advice concerning php/mysql welcome too!

Answer 1

First, make sure PDO is set to throw exceptions if a query fails:
$con->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
Then, perhaps catch the exception (or let the exception halt the application) and see what is wrong.
I do believe your insert query is, erm, off:
INSERT INTO tblname (id)
SELECT tblname2.colname
FROM tablename2
WHERE col1 = "val"
Just seems ambiguous, and messy, even more: it seems unsafe. However, try this -equally messy- query:
INSERT INTO tblname (id) VALUES (
SELECT colname
FROM tblname2
WHERE col1 = "val"
);
Last but not least, make sure you're running PHP version 5.3+, because prior to that version, PDO did not support multiple queries.
My suggestion, though, is not to use multiple queries for the INSERT query. Instead, I'd use a transaction and separate the select and insert query. I'd also add a safety-net to the DROP TABLE and CREATE TABLE queries, too:
try
{
$con->beginTransaction();//DROP & CREATE:
if ($con->exec('DROP TABLE IF EXISTS tblname') === false)
{//query wasn't executed
$con->rollback();
exit($con->errInfo());//error
}
if ($con->exec('CREATE TABLE IF NOT EXISTS tblname(...);') === false)
{
$con->rollback();
exit($con->errInfo());
}
$con->commit();//alter tables.
$con->beginTransaction();//INSERT TRANSACTION
$stmt = $con->prepare('INSERT INTO tblname (id) VALUES (:id)');
$bind = array(
':id' => null
);
$select = $con->prepare(
'SELECT colname FROM tblname2 WHERE col1 = :val1 AND col2 = :val2'
);
$select->execute(
array(
':val1' => 'value1',
':val2' => 'value2'
)
);
while ($row = $select->fetch(PDO::FETCH_ASSOC))
{
$bind[':id'] = $row['colname'];
$stmt->execute($bind);//inserts row
$stmt->closeCursor();//optional
}
$con->commit();//save changes to db
}
catch (PDOException $e)
{
//rollback transaction
$con->rollback();
exit($e->getMessage());//show what went wrong, and exit.
}

Answer 2

You are missing a keyword here to INSERT the value into the table, which is VALUES.
The correct syntax will be
INSERT INTO tblname (id) VALUES
SELECT tablename2.colname
FROM tablename2
WHERE (col1 = 'value' AND col2 = 'value')
The values should be into SINGLE QUOTES, tried and test myself and these 2 work for me every time.!