Example calls to D7 database API

sample_db_calls.php

<?php

// Query and loop over results
$result = db_select('node', 'n')
  ->fields('n', array('nid'))
  ->condition('type', 'article')
  ->condition('uid', array(0,1), 'IN')
  ->execute();
 
foreach($result as $row) {
  // process row
  print $row->nid;
}

// Another way to query and loop over results. The first
// one is the recommended for new code.
$result = db_query("SHOW TABLES");
  
if ($result) {
  while ($row = $result->fetch(PDO::FETCH_NUM)) {
    // process each row
    // ..
  }
}

// Execute a query that counts
$number_of_rows = db_select('node')
  ->countQuery()
  ->execute()
  ->fetchField();

// Execute a query that retrieves a single column
// from a single row:
$number_of_rows = db_select('users', 'u')
  ->fields('u' ,array('name'))
  ->condition('uid', 1)
  ->execute()
  ->fetchField();

// Execute a single query disregarding results
db_query("RENAME TABLE {$table_old} TO {$table_new}");

// More examples here: https://www.drupal.org/developing/api/database

?>