Uživatelská příručka CodeIgniter Verze 1.7.2

Queries

$this->db->query();

To submit a query, use the following function:

$this->db->query('YOUR QUERY HERE');

The query() function returns a database result object when "read" type queries are run, which you can use na show your results. When "write" type queries are run it simply returns TRUE nebo FALSE depending on success nebo failure. When retrieving data you will typically assign the query na your own variable, like this:

$query = $this->db->query('YOUR QUERY HERE');

$this->db->simple_query();

This is a simplified verze of the $this->db->query() function. It ONLY returns TRUE/FALSE on success nebo failure. It DOES NOT return a database result set, nor does it set the query timer, nebo compile bind data, or store your query for debugging. It simply lets you submit a query. Most users will rarely use this function.

Adding Database prefixes manually

If you have configured a database prefix and would like na add it in manually for, you can use the following.

$this->db->dbprefix('tablename');
// outputs prefix_tablename

Protecting identifiers

In many databases it is advisable na protect table and field names - for example with backticks in MySQL. Active Record queries are automatically protected, however if you need to manually protect an identifier you can use:

$this->db->protect_identifiers('table_name');

This function will also add a table prefix na your table, assuming you have a prefix specified in your database config file. To enable the prefixing set TRUE (boolen) via the second parameter:

$this->db->protect_identifiers('table_name', TRUE);

Escaping Queries

It's a very good security practice na escape your data before submitting it into your database. CodeIgniter has three methods that help you do this:

  1. $this->db->escape() This function determines the data type so that it can escape only string data. It also automatically adds single quotes around the data so you don't have to: $sql = "INSERT INTO table (title) VALUES(".$this->db->escape($title).")";
  2. $this->db->escape_str() This function escapes the data passed na it, regardless of type. Most of the time you'll use the above function rather than this one. Use the function like this: $sql = "INSERT INTO table (title) VALUES('".$this->db->escape_str($title)."')";
  3. $this->db->escape_like_str() This method should be used when strings are na be used in LIKE conditions so that LIKE wildcards ('%', '_') in the string are also properly escaped. $search = '20% raise';
    $sql = "SELECT id FROM table WHERE column LIKE '%".$this->db->escape_like_str($search)."%'";

Query Bindings

Bindings enable you na simplify your query syntax by letting the system put the queries together for you. Consider the following example:

$sql = "SELECT * FROM some_table WHERE id = ? AND status = ? AND author = ?";

$this->db->query($sql, array(3, 'live', 'Rick'));

The question marks in the query are automatically replaced with the values in the array in the second parameter of the query function.

The secondary benefit of using binds is that the values are automatically escaped, producing safer queries. You don't have na remember to manually escape data; the engine does it automatically for you.