How do you manage SQL Queries

There are some libraries, such as MDB2 in PEAR that make querying a bit easier and safer.

Unfortunately, they can be a bit wordy to set up, and you sometimes have to pass them the same info twice. I've used MDB2 in a couple of projects, and I tended to write a thin veneer around it, especially for specifying the types of fields. I generally make an object that knows about a particular table and its columns, and then a helper function in that fills in field types for me when I call an MDB2 query function.

For instance:

function MakeTableTypes($TableName, $FieldNames)
{
    $Types = array();

    foreach ($FieldNames as $FieldName => $FieldValue)
    {
        $Types[] = $this->Tables[$TableName]['schema'][$FieldName]['type'];
    }

    return $Types;
}

Obviously this object has a map of table names -> schemas that it knows about, and just extracts the types of the fields you specify, and returns an matching type array suitable for use with an MDB2 query.

MDB2 (and similar libraries) then handle the parameter substitution for you, so for update/insert queries, you just build a hash/map from column name to value, and use the 'autoExecute' functions to build and execute the relevant query.

For example:

function UpdateArticle($Article)
{
    $Types = $this->MakeTableTypes($table_name, $Article);

    $res = $this->MDB2->extended->autoExecute($table_name,
        $Article,
        MDB2_AUTOQUERY_UPDATE,
        'id = '.$this->MDB2->quote($Article['id'], 'integer'),
        $Types);
}

and MDB2 will build the query, escaping everything properly, etc.

I'd recommend measuring performance with MDB2 though, as it pulls in a fair bit of code that might cause you problems if you're not running a PHP accelerator.

As I say, the setup overhead seems daunting at first, but once it's done the queries can be simpler/more symbolic to write and

This other question also has some useful links in it...