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author | Joël Cox <joel@joelcox.nl> | 2011-10-09 18:45:09 +0200 |
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committer | Joël Cox <joel@joelcox.nl> | 2011-10-09 18:45:09 +0200 |
commit | 8ffcb2c8c7ef3da54d7e46c29d502533e413c820 (patch) | |
tree | 1f94e2e81b4d20f2df827b8a84eeda27032161a1 /user_guide_src/source/database/results.rst | |
parent | f4fb1db458fab52d0493ead52c9ea7e01206eaa7 (diff) | |
parent | 6858c0753a7221796d6a5a1d7fea93cc2f9feb2e (diff) |
Merged develop branch in tutorial.
Diffstat (limited to 'user_guide_src/source/database/results.rst')
-rw-r--r-- | user_guide_src/source/database/results.rst | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/user_guide_src/source/database/results.rst b/user_guide_src/source/database/results.rst new file mode 100644 index 000000000..4f93c794d --- /dev/null +++ b/user_guide_src/source/database/results.rst @@ -0,0 +1,186 @@ +######################## +Generating Query Results +######################## + +There are several ways to generate query results: + +result() +======== + +This function returns the query result as an array of **objects**, or +**an empty array** on failure. Typically you'll use this in a foreach +loop, like this:: + + $query = $this->db->query("YOUR QUERY"); + + foreach ($query->result() as $row) + { + echo $row->title; + echo $row->name; + echo $row->body; + } + +The above function is an alias of result_object(). + +If you run queries that might **not** produce a result, you are +encouraged to test the result first:: + + $query = $this->db->query("YOUR QUERY"); + + if ($query->num_rows() > 0) + { + foreach ($query->result() as $row) + { + echo $row->title; + echo $row->name; + echo $row->body; + } + } + +You can also pass a string to result() which represents a class to +instantiate for each result object (note: this class must be loaded) + +:: + + $query = $this->db->query("SELECT * FROM users;"); + + foreach ($query->result('User') as $user) + { + echo $user->name; // call attributes + echo $user->reverse_name(); // or methods defined on the 'User' class + } + +result_array() +=============== + +This function returns the query result as a pure array, or an empty +array when no result is produced. Typically you'll use this in a foreach +loop, like this:: + + $query = $this->db->query("YOUR QUERY"); + + foreach ($query->result_array() as $row) + { + echo $row['title']; + echo $row['name']; + echo $row['body']; + } + +row() +===== + +This function returns a single result row. If your query has more than +one row, it returns only the first row. The result is returned as an +**object**. Here's a usage example:: + + $query = $this->db->query("YOUR QUERY"); + + if ($query->num_rows() > 0) + { + $row = $query->row(); + + echo $row->title; + echo $row->name; + echo $row->body; + } + +If you want a specific row returned you can submit the row number as a +digit in the first parameter:: + + $row = $query->row(5); + +You can also add a second String parameter, which is the name of a class +to instantiate the row with:: + + $query = $this->db->query("SELECT * FROM users LIMIT 1;"); + $query->row(0, 'User'); + + echo $row->name; // call attributes + echo $row->reverse_name(); // or methods defined on the 'User' class + +row_array() +============ + +Identical to the above row() function, except it returns an array. +Example:: + + $query = $this->db->query("YOUR QUERY"); + + if ($query->num_rows() > 0) + { + $row = $query->row_array(); + + echo $row['title']; + echo $row['name']; + echo $row['body']; + } + +If you want a specific row returned you can submit the row number as a +digit in the first parameter:: + + $row = $query->row_array(5); + +In addition, you can walk forward/backwards/first/last through your +results using these variations: + + | **$row = $query->first_row()** + | **$row = $query->last_row()** + | **$row = $query->next_row()** + | **$row = $query->previous_row()** + +By default they return an object unless you put the word "array" in the +parameter: + + | **$row = $query->first_row('array')** + | **$row = $query->last_row('array')** + | **$row = $query->next_row('array')** + | **$row = $query->previous_row('array')** + +*********************** +Result Helper Functions +*********************** + +$query->num_rows() +=================== + +The number of rows returned by the query. Note: In this example, $query +is the variable that the query result object is assigned to:: + + $query = $this->db->query('SELECT * FROM my_table'); + + echo $query->num_rows(); + +$query->num_fields() +===================== + +The number of FIELDS (columns) returned by the query. Make sure to call +the function using your query result object:: + + $query = $this->db->query('SELECT * FROM my_table'); + + echo $query->num_fields(); + +$query->free_result() +====================== + +It frees the memory associated with the result and deletes the result +resource ID. Normally PHP frees its memory automatically at the end of +script execution. However, if you are running a lot of queries in a +particular script you might want to free the result after each query +result has been generated in order to cut down on memory consumptions. +Example:: + + $query = $this->db->query('SELECT title FROM my_table'); + + foreach ($query->result() as $row) + { + echo $row->title; + } + $query->free_result(); // The $query result object will no longer be available + + $query2 = $this->db->query('SELECT name FROM some_table'); + + $row = $query2->row(); + echo $row->name; + $query2->free_result();// The $query2 result object will no longer be available + |