How to work with database in Drupal 7

// Drupal 6 version
$nodes = db_query("
SELECT nid, title FROM {node}
  WHERE type = '%s' AND uid = %d
", 'page', 1);
 
// Drupal 7, static query
$nodes = db_query("
  SELECT nid, title FROM {node}
  WHERE type = :type AND uid = :uid
", array(':type' => 'page', ':uid' => 1))->fetchAll();
 
// Drupal 7, dynamic query
$nodes = db_select('node', 'n')
  ->fields('n', array('nid', 'title'))
  ->condition('n.type', 'page')
  ->condition('n.uid', 1)
  ->execute()
  ->fetchAll();

// Drupal 6 version
$title = db_result(db_query("SELECT title FROM {node} WHERE nid = %d", 123));
 
// Drupal 7, static query
$title = db_query("SELECT title FROM {node} WHERE nid = :nid", array(':nid' => 123))->fetchField();
 
// Drupal 7, dynamic query
$title = db_select('node', 'n')
  ->fields('n', array('title'))
  ->condition('n.nid', 123)
  ->execute()
  ->fetchField();

// Drupal 6
$count = db_result(db_query("SELECT COUNT(*) FROM {node} n WHERE n.uid = 1"));
 
// Drupal 7, static query
$count = db_query("SELECT COUNT(*) FROM {node} n WHERE n.uid = 1")->fetchField();
 
// Drupal 7, dynamic query, example 1
$count = db_select('node', 'n')
  ->condition('n.uid', 1)
  ->countQuery()
  ->execute()
  ->fetchField();
 
// Drupal 7, dynamic query, example 2
$query = db_select('node');
$query->addExpression('COUNT(*)');
$count = $query->execute()->fetchField();

// Drupal 6 version
$nodes = db_query("SELECT * FROM {node} LIMIT 0, 10");
 
// Drupal 7, static query
$nodes = db_query("SELECT * FROM {node} LIMIT 0, 10")->fetchAll();
 
// Drupal 7, dynamic query
$nodes = db_select('node', 'n')
  ->fields('n')
  ->range(0, 10)
  ->execute()
  ->fetchAll();

// Drupal 6
db_query("UPDATE {node} SET status = %d WHERE nid = %d", 1, 123);
 
// Drupal 7, static query
db_query("UPDATE {node} SET status = :status WHERE nid = :nid", array(':status' => 1, ':nid' => 123));
 
// Drupal 7, dynamic query
db_update('node')
  ->fields(array('status' => 1))
  ->condition('nid', 123)
  ->execute();

// Drupal 6
db_query("DELETE FROM {node} WHERE uid = %d AND created < %d", 1, time() - 3600);
 
// Drupal 7, static query
db_query("DELETE FROM {node} WHERE uid = :uid AND created < :created", array(':uid' => 1, ':created' => time() - 3600));
 
// Drupal 7, dynamic query
db_delete('node')
  ->condition('uid', 1)
  ->condition('created', time() - 3600, '<')
  ->execute();

// Drupal 6
db_query("INSERT INTO {mytable} (intvar, stringvar, floatvar) VALUES (%d, '%s', %f)", 5, 'yum yum', 3.14);
$id = db_last_insert_id();
 
// Drupal 7, dynamic query
$id = db_insert('mytable')
  ->fields(array(
    'intvar' => 5,
    'stringvar' => 'yum yum',
    'floatvar' => 3.14,
  ))
  ->execute();

// Drupal 6
$nodes = db_query("SELECT * FROM {node} WHERE nid BETWEEN %d AND %d", 123, 456);
 
// Drupal 7, static query
$nodes = db_query("SELECT * FROM {node} WHERE nid BETWEEN :nid1 AND :nid2", array(':nid1' => 123, ':nid2' => 456))->fetchAll();
 
// Drupal 7, dynamic query
$nodes = db_select('node', 'n')
  ->fields('n')
  ->condition('n.nid', array(123, 456), 'BETWEEN')
  ->execute()
  ->fetchAll();

// Drupal 6
$nodes = db_query("SELECT * FROM {node} WHERE YEAR(FROM_UNIXTIME(created)) = %d", 2011);
 
// Drupal 7, static query
$nodes = db_query("SELECT * FROM {node} WHERE YEAR(FROM_UNIXTIME(created)) = :created", array(':created' => 2011))->fetchAll();
 
// Drupal 7, dynamic query
$nodes = db_select('node', 'n')
  ->fields('n')
  ->where('YEAR(FROM_UNIXTIME(n.created)) = :created', array(':created' => 2011))
  ->execute()
  ->fetchAll();

// Drupal 6
$result = db_query("SELECT nid, title, created FROM {node}");
$nodes = array();
while ($row = db_fetch_object($result)) {
  $nodes[$row->nid] = $row;
}
 
// Drupal 7, static query
$nids = db_query("SELECT nid, title, created FROM {node}")->fetchAllAssoc('nid');
 
// Drupal 7, dynamic query
$nids = db_select('node', 'n')
  ->fields('n', array('nid', 'title', 'created'))
  ->execute()
  ->fetchAllAssoc('nid');