How do I query multiple choices against one db table-field?

[wscreate]

I have data in comma-separated format such as this.

$theAttachID = "[e-mail],[e-mail],[e-mail]";

I have a mysql database that contains a users data. There is a field name called "Email" that contains one email address for the user. I want to check the value of "Email" with an sql query to check against the data contained in the variable "$theAttachID". Someone suggested to me to use IN() with my sql query such as this.

Ex.
$sqlquery = "SELECT * FROM Customers WHERE Email IN ($theAttachID)";

But this doesn't work. I suspect that in() only works with numeric values as it will work with numbers but not with email addresses.

Anyway, my question to the community is, how can I efficiently code an sql query that will check the information in variable "$data" against the "Email" field in my database table? Note, the "$data" variable may hold up to several dozen email addresses in it, so finding a way to do this efficiently at query time is important.

Thanks for any suggestions.

[NogDog]

You need to end up quoting each string literal separately within the IN() clause, separated by commas.

$inString = "'" . str_replace(',', "', '", $theAttachID) . "'";
$sqlquery = "SELECT * FROM Customers WHERE Email IN ($inString)";

[wscreate]

NogDog wrote:

You need to end up quoting each string literal separately within the IN() clause, separated by commas.

$inString = "'" . str_replace(',', "', '", $theAttachID) . "'";
$sqlquery = "SELECT * FROM Customers WHERE Email IN ($inString)";

Thanks nogdog. Why is it that it is not necessary to quote the string literals separately when the data is numeric...

Example:
$theAttachID = "33345, 233332, 111209, 999883";

Plugging that data into this sql query works fine....

$sqlquery = "SELECT * FROM Customers WHERE Email IN ($theAttachID)";

??

[NogDog]

Because SQL knows that a number is a number, but a non-numeric value which is not quoted will be treated as either a database column name or table name, or possibly a SQL reserved word, if it is not quoted.

[bradgrafelman]

In other words, it's the same as PHP. Would you expect the following to work in PHP?

$var = Some text here. Oh, in fact, let's add some more text on...
... the next line!;

Of course not. PHP doesn't understand that you're giving it a string - just like SQL.