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diff --git a/user_guide_src/source/database/queries.rst b/user_guide_src/source/database/queries.rst deleted file mode 100644 index f626f1e83..000000000 --- a/user_guide_src/source/database/queries.rst +++ /dev/null @@ -1,176 +0,0 @@ -####### -Queries -####### - -************ -Query Basics -************ - -Regular Queries -=============== - -To submit a query, use the **query** 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 to :doc:`show your -results <results>`. When "write" type queries are run it simply -returns TRUE or FALSE depending on success or failure. When retrieving -data you will typically assign the query to your own variable, like -this:: - - $query = $this->db->query('YOUR QUERY HERE'); - -Simplified Queries -================== - -The **simple_query** method is a simplified version of the -$this->db->query() method. 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. It simply lets you -submit a query. Most users will rarely use this function. - -It returns whatever the database drivers' "execute" function returns. -That typically is TRUE/FALSE on success or failure for write type queries -such as INSERT, DELETE or UPDATE statements (which is what it really -should be used for) and a resource/object on success for queries with -fetchable results. - -:: - - if ($this->db->simple_query('YOUR QUERY')) - { - echo "Success!"; - } - else - { - echo "Query failed!"; - } - -.. note:: PostgreSQL's ``pg_exec()`` function (for example) always - returns a resource on success, even for write type queries. - So take that in mind if you're looking for a boolean value. - -*************************************** -Working with Database prefixes manually -*************************************** - -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:: - - $this->db->dbprefix('tablename'); // outputs prefix_tablename - - -If for any reason you would like to change the prefix programatically -without needing to create a new connection, you can use this method:: - - $this->db->set_dbprefix('newprefix'); - $this->db->dbprefix('tablename'); // outputs newprefix_tablename - - -********************** -Protecting identifiers -********************** - -In many databases it is advisable to protect table and field names - for -example with backticks in MySQL. **Query Builder queries are -automatically protected**, however if you need to manually protect an -identifier you can use:: - - $this->db->protect_identifiers('table_name'); - -.. important:: Although the Query Builder will try its best to properly - quote any field and table names that you feed it, note that it - is NOT designed to work with arbitrary user input. DO NOT feed it - with unsanitized user data. - -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 TRUE (boolean) via the second parameter:: - - $this->db->protect_identifiers('table_name', TRUE); - - -**************** -Escaping Queries -**************** - -It's a very good security practice to escape your data before submitting -it into your database. CodeIgniter has three methods that help you do -this: - -#. **$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($title).")"; - -#. **$this->db->escape_str()** This function escapes the data passed to - 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($title)."')"; - -#. **$this->db->escape_like_str()** This method should be used when - strings are to 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)."%' ESCAPE '!'"; - -.. important:: The ``escape_like_str()`` method uses '!' (exclamation mark) - to escape special characters for *LIKE* conditions. Because this - method escapes partial strings that you would wrap in quotes - yourself, it cannot automatically add the ``ESCAPE '!'`` - condition for you, and so you'll have to manually do that. - - -************** -Query Bindings -************** - -Bindings enable you to 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. - -Binding also work with arrays, which will be transformed to IN sets:: - - $sql = "SELECT * FROM some_table WHERE id IN ? AND status = ? AND author = ?"; - $this->db->query($sql, array(array(3, 6), 'live', 'Rick')); - -The resulting query will be:: - - SELECT * FROM some_table WHERE id IN (3,6) AND status = 'live' AND author = 'Rick' - -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. - -*************** -Handling Errors -*************** - -**$this->db->error();** - -If you need to get the last error that has occurred, the error() method -will return an array containing its code and message. Here's a quick -example:: - - if ( ! $this->db->simple_query('SELECT `example_field` FROM `example_table`')) - { - $error = $this->db->error(); // Has keys 'code' and 'message' - } - |