oci8: fix warning in qStr() with NULL on PHP 8.1

This is a follow-up commit on 1501ccd07868d626a51802d14ed41ed05a3532ad,
as the original fix for #999 (see PR #1005) did not fully address the
problem. Another PHP deprecated warning is thrown:

strlen(): Passing null to parameter 1 ($string) of type string is
deprecated.

Fixes #1012

Backported from commit 8d88183538ae08b86c30af5b0f3280c2accd71c3.

2 files changed, 8 insertions, 7 deletions

diff --git a/adodb-datadict.inc.php b/adodb-datadict.inc.php
index 5156b1f9..b603d8de 100644
--- a/adodb-datadict.inc.php
+++ b/adodb-datadict.inc.php
@@ -1027,7 +1027,6 @@ class ADODB_DataDict {
 	function changeTableSQL($tablename, $flds, $tableoptions = false, $dropOldFlds=false)
 	{
 	global $ADODB_FETCH_MODE;
-
 		$save = $ADODB_FETCH_MODE;
 		$ADODB_FETCH_MODE = ADODB_FETCH_ASSOC;
 		if ($this->connection->fetchMode !== false) $savem = $this->connection->setFetchMode(false);
@@ -1074,15 +1073,20 @@ class ADODB_DataDict {
 					if ($mt == 'X') $ml = $v['SIZE'];
 					if (($mt != $v['TYPE']) || ($ml != $fsize || $sc != $fprec) || (isset($v['AUTOINCREMENT']) && $v['AUTOINCREMENT'] != $obj->auto_increment)) {
 						$holdflds[$k] = $v;
+						$fields_to_alter[$k] = $v;
 					}
 				} else {
+					$fields_to_add[$k] = $v;
 					$holdflds[$k] = $v;
 				}
 			}
 			$flds = $holdflds;
 		}
 
-		$sql = $this->alterColumnSql($tablename, $flds);
+		$sql = array_merge(
+			$this->addColumnSQL($tablename, $fields_to_add),
+			$this->alterColumnSql($tablename, $fields_to_alter)
+		);
 
 		if ($dropOldFlds) {
 			foreach ($cols as $id => $v) {
diff --git a/drivers/adodb-oci8.inc.php b/drivers/adodb-oci8.inc.php
index 965c1621..b92281c7 100644
--- a/drivers/adodb-oci8.inc.php
+++ b/drivers/adodb-oci8.inc.php
@@ -1576,11 +1576,8 @@ SELECT /*+ RULE */ distinct b.column_name
 	 */
 	function qStr($s, $magic_quotes=false)
 	{
-		if ($this->noNullStrings && strlen($s) == 0) {
-			$s = ' ';
-		}
-		else if (strlen($s) == 0) {
-			return "''";
+		if (strlen((string)$s) == 0) {
+			return $this->noNullStrings ? "' '" : "''";
 		}
 		if ($this->replaceQuote[0] == '\\'){
 			$s = str_replace('\\','\\\\',$s);