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Oracle Tips by Burleson |
Auxiliary OCI8 Functions
When a query is executed, Oracle creates a result
set. This result set has to be transferred to the executing script by
fetching it. This section explains how to retrieve and describe result
sets. In Example 16, the only function called to do a fetch is
oci_fetch($usr); in which $usr is a statement handle. The
oci_fetch() function is used to illustrate a call to
oci_define(). There are several more functions to facilitate
fetching the data from an Oracle database to the program and
oci_fetch_array() is the most frequently used one.
This function is shown in Example 15; the results
of the query are fetched using the oci_fetch_array function.
The statement block in question is this one:
while
($row=oci_fetch_array($sth)) {
echo $row[0],"\t",$row[1],"\t",$row[2],
"\t",$row[3],"\n"; }
No define step has ever been done in Example 15 and the
function used, oci_fetch_array(), returned an array named
$row. The oci_fetch_array() function can return either a
numeric array, an associative array (hash) or both. The default is to
return both. Here is the description of the oci_fetch_aray()
from the manual:
DESCRIPTION
Returns an array, which corresponds to the next
result row or in FALSE case of error or there is no more rows in the
result.
oci_fetch_array()
returns an array with both associative and numeric indices.
Note: This function sets NULLfields to PHP NULL
value.
Optional second parameter can be any combination
of the following constants:
-
oci_both - return an array with both associative
and numeric indices (the same as oci_assoc + oci_num). This is the
default behavior.
-
oci_assoc - return an associative array (as
oci_fetch_assoc() works).
-
oci_num - return a numeric array, (as
oci_fetch_row() works).
-
oci_return_nulls - create empty elements for the
NULL fields.
-
oci_return_lobs - return the value of a LOB of
the descriptor. Default mode is
oci_both.
It should be mentioned here, that
oci_fetch_array() is insignificantly slower than
oci_fetch_row(), but much more handy. It must also be noted that
Oracle returns all field names in uppercase and associative indices in
the result array are uppercased too.
The remark about being slower than
oci_fetch_row() also applies to the bare bones oci_fetch().
There are separate functions to fetch the next row into an associative
array, a numeric array or an object. Not surprisingly, these functions
are called oci_fetch_assoc(), oci_fetch_row() and
oci_fetch_object(). For the query “select * from dept”, the
oci_fetch_object() function returns the next row as an object
belonging to the class defined as follows:
class row {
public $DEPTNO,
public $DNAME,
public $LOC }
In other words, instead of fetching into an array,
the row is packaged into an object and accessed correspondingly by
using the OO syntax, like this: $d->DEPTNO, $d->DNAME and $d->LOC.
Fetching rows into objects is used relatively infrequently in real
world database applications. The call that is most frequently used is
oci_fetch_array() which is completely sufficient for most
applications, including the analyze_schema.php from the example 16.
Despite the numerous attempts of blending databases and object
orientation, these two paradigms are still separated by a wide gap.
Things like object-relational features of Oracle RDBMSand pure object databases have relatively few followers,
compared to the number of users and applications that use databases in
the traditional way.
The oci_fetch_aray() function returns each
row as an array, both the associative array and an array indexed by
number. This means that if the query is asking for N columns, the
oci_fetch_array() will contain 2*N elements. If one or another is
desired, OCI_ASSOC or OCI_NUM flags should be used. The default is
both. This is really important if correct results are wanted when
looping through the fetched row by using the “foreach” statement.
See
code depot for complete scripts
The above book excerpt is from:
Easy Oracle
PHP
Create Dynamic Web Pages with Oracle Data
ISBN
0-9761573-0-6
Mladen Gogala
http://www.rampant-books.com/book_2005_2_php_oracle.htm
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