oci_fetch与oci_fetch_array

Question

When would it be advantageous to use oci_fetch over oci_fetch_array? oci_fetch_array returns the actual array, but oci_fetch just stores the fetched memory somewhere in its internal buffers.

Are there any performance differences between the two I should know about?

Answer 1

With oci_fetch(), the next result row is read into internal buffers that can be read by oci_result(). So you would do the call like this:

$st_handle = oci_parse($oci_conn, 'SELECT some_field, another_field FROM some_table');
oci_execute($st_handle);
while(oci_fetch($st_handle)) {
   $some_field = oci_result($st_handle, 'some_field');
   var_dump($some_field);
   $another_field = oci_result($st_handle, 'another_field');
   var_dump($another_field);
}

Alternately, instead of using oci_result() you can pre-define the variables you will load into the internal buffer using oci_define_by_name() like this:

$st_handle = oci_parse($oci_conn, 'SELECT some_field, another_field FROM some_table');
oci_define_by_name($st_handle, 'some_field', $some_field);
oci_define_by_name($st_handle, 'another_field', $another_field);
oci_execute($st_handle);
while(oci_fetch($st_handle)) {
   var_dump($some_field);
   var_dump($another_field);
}

Obviously, this is more verbose than using something like oci_fetch_array() or oci_fetch_object() where you don't need to explicitly define variables to read the results into.

$st_handle = oci_parse($oci_conn, 'SELECT some_field, another_field FROM some_table');
oci_execute($st_handle);
while($row = oci_fetch_array($st_handle, OCI_ASSOC)) {
   var_dump($row['some_field']);
   var_dump($row['another_field']);
}

There shouldn't be any significant performance difference. Either way, you are eventually going to need to assign the result set into the memory of a variable or variables that you can use.