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60 | ||
61 | ||
62 | <h1>Queries</h1> | |
63 | ||
64 | <h2>$this->db->query();</h2> | |
65 | ||
66 | <p>To submit a query, use the following function:</p> | |
67 | ||
68 | <code>$this->db->query('YOUR QUERY HERE');</code> | |
69 | ||
70 | <p>The <dfn>query()</dfn> function returns a database result <strong>object</strong> when "read" type queries are run, | |
71 | which you can use to <a href="results.html">show your results</a>. When "write" type queries are run it simply returns TRUE or FALSE | |
72 | depending on success or failure. When retrieving data you will typically assign the query to your own variable, like this:</p> | |
73 | ||
74 | <code><var>$query</var> = $this->db->query('YOUR QUERY HERE');</code> | |
75 | ||
76 | <h2>$this->db->simple_query();</h2> | |
77 | ||
78 | <p>This is a simplified version of the <dfn>$this->db->query()</dfn> function. It ONLY returns TRUE/FALSE on success or failure. | |
79 | It DOES NOT return a database result set, nor does it set the query timer, or compile bind data, or store your query for debugging. | |
80 | It simply lets you submit a query. Most users will rarely use this function.</p> | |
81 | ||
82 | ||
83 | <h1>Working with Database prefixes manually</h1> | |
84 | <p>If you have configured a database prefix and would like to prepend it to a table name for use in a native SQL query for example, then you can use the following:</p> | |
85 | <p><code>$this->db->dbprefix('tablename');<br /> | |
86 | // outputs prefix_tablename</code></p> | |
87 | ||
88 | <p>If for any reason you would like to change the prefix programatically without needing to create a new connection, you can use this method:</p> | |
89 | <p><code>$this->db->set_dbprefix('newprefix');<br /><br /> | |
90 | $this->db->dbprefix('tablename');<br /> | |
91 | // outputs newprefix_tablename</code></p> | |
92 | ||
93 | ||
94 | <h1>Protecting identifiers</h1> | |
95 | <p>In many databases it is advisable to protect table and field names - for example with backticks in MySQL. <strong>Active Record queries are automatically protected</strong>, however if you need to manually protect an identifier you can use:</p> | |
96 | <p><code>$this->db->protect_identifiers('table_name');</code></p> | |
97 | ||
98 | <p>This function will also add a table prefix to your table, assuming you have a prefix specified in your database config file. To enable the prefixing set <kbd>TRUE</kbd> (boolen) via the second parameter:</p> | |
99 | <p><code>$this->db->protect_identifiers('table_name', <kbd>TRUE</kbd>);</code></p> | |
100 | ||
101 | ||
102 | <h1>Escaping Queries</h1> | |
103 | <p>It's a very good security practice to escape your data before submitting it into your database. | |
104 | CodeIgniter has three methods that help you do this:</p> | |
105 | ||
106 | <ol> | |
107 | <li><strong>$this->db->escape()</strong> This function determines the data type so that it | |
108 | can escape only string data. It also automatically adds single quotes around the data so you don't have to: | |
109 | ||
110 | <code>$sql = "INSERT INTO table (title) VALUES(".$this->db->escape($title).")";</code></li> | |
111 | ||
112 | <li><strong>$this->db->escape_str()</strong> This function escapes the data passed to it, regardless of type. | |
113 | Most of the time you'll use the above function rather than this one. Use the function like this: | |
114 | ||
115 | <code>$sql = "INSERT INTO table (title) VALUES('".$this->db->escape_str($title)."')";</code></li> | |
116 | ||
117 | <li><strong>$this->db->escape_like_str()</strong> This method should be used when strings are to be used in LIKE | |
118 | conditions so that LIKE wildcards ('%', '_') in the string are also properly escaped. | |
119 | ||
120 | <code>$search = '20% raise';<br /> | |
121 | $sql = "SELECT id FROM table WHERE column LIKE '%".$this->db->escape_like_str($search)."%'";</code></li> | |
122 | ||
123 | </ol> | |
124 | ||
125 | ||
126 | <h1>Query Bindings</h1> | |
127 | ||
128 | ||
129 | <p>Bindings enable you to simplify your query syntax by letting the system put the queries together for you. Consider the following example:</p> | |
130 | ||
131 | <code> | |
132 | $sql = "SELECT * FROM some_table WHERE id = <var>?</var> AND status = <var>?</var> AND author = <var>?</var>"; | |
133 | <br /><br /> | |
134 | $this->db->query($sql, array(3, 'live', 'Rick')); | |
135 | </code> | |
136 | ||
137 | <p>The question marks in the query are automatically replaced with the values in the array in the second parameter of the query function.</p> | |
138 | <p class="important">The secondary benefit of using binds is that the values are automatically escaped, producing safer queries. You don't have to remember to manually escape data; the engine does it automatically for you.</p> | |
139 | ||
140 | ||
141 | ||
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