update policy and fix other issues

app/Models/StudentClassModel.php

@@ -55,7 +55,12 @@ class StudentClassModel extends Model
         return $this->db->table($this->table);
     }
 
-    private function includeActiveOrTerminalEnrollment(BaseBuilder $builder, string $schoolYear): BaseBuilder
+    private function includeActiveOrTerminalEnrollment(
+        BaseBuilder $builder,
+        string $schoolYear,
+        bool $hasEnrollmentStatus = false,
+        bool $hasEnrollmentWithdrawn = false
+    ): BaseBuilder
     {
         $terminalStatuses = array_map([$this->db, 'escape'], [
             'denied',
@@ -66,13 +71,16 @@ class StudentClassModel extends Model
         $builder->groupStart()
             ->where('students.is_active', 1);
 
-        if ($schoolYear !== '') {
+        if ($schoolYear !== '' && $hasEnrollmentStatus) {
             $builder->orWhere(
                 'LOWER(TRIM(enrollments.enrollment_status)) IN (' . implode(',', $terminalStatuses) . ')',
                 null,
                 false
-            )
-                ->orWhere('enrollments.is_withdrawn', 1);
+            );
+        }
+
+        if ($schoolYear !== '' && $hasEnrollmentWithdrawn) {
+            $builder->orWhere('enrollments.is_withdrawn', 1);
         }
 
         return $builder->groupEnd();
@@ -446,44 +454,61 @@ class StudentClassModel extends Model
 
         $schoolYear = $schoolYear !== null ? trim($schoolYear) : '';
 
+        $hasStudentYearStatus = $this->db->tableExists('student_year_status')
+            && $this->db->fieldExists('is_new', 'student_year_status');
+        $hasEventOnly = $this->db->fieldExists('is_event_only', 'student_class');
+        $hasEnrollments = $this->db->tableExists('enrollments');
+        $hasEnrollmentStatus = $hasEnrollments && $this->db->fieldExists('enrollment_status', 'enrollments');
+        $hasEnrollmentWithdrawn = $hasEnrollments && $this->db->fieldExists('is_withdrawn', 'enrollments');
+
+        $select = [
+            'students.id AS student_id',
+            'students.firstname',
+            'students.lastname',
+            'students.school_id',
+            'students.is_active',
+            $hasStudentYearStatus ? 'COALESCE(sys.is_new, 1) AS is_new' : '1 AS is_new',
+            'students.photo_consent',
+            'students.age',
+            'student_class.school_year',
+            'student_class.class_section_id',
+            $hasEventOnly ? 'student_class.is_event_only' : '0 AS is_event_only',
+            $hasEnrollmentStatus ? 'enrollments.enrollment_status' : 'NULL AS enrollment_status',
+            $hasEnrollmentWithdrawn ? 'enrollments.is_withdrawn' : '0 AS is_withdrawn',
+        ];
+
         $builder = $this->freshBuilder()
-            ->select([
-                'students.id AS student_id',
-                'students.firstname',
-                'students.lastname',
-                'students.school_id',
-                'students.is_active',
-                'COALESCE(sys.is_new, 1) AS is_new',
-                'students.photo_consent',
-                'students.age',
-                'student_class.school_year',
-                'student_class.class_section_id',
-                'student_class.is_event_only',
-                'enrollments.enrollment_status',
-                'enrollments.is_withdrawn',
-            ])
+            ->select($select)
             ->join(
                 'students',
                 'students.id = student_class.student_id',
                 'inner'
-            )
-            ->join(
+            );
+
+        if ($hasStudentYearStatus) {
+            $builder->join(
                 'student_year_status sys',
                 $schoolYear !== ''
                     ? 'sys.student_id = students.id AND sys.school_year = ' . $this->db->escape($schoolYear)
                     : 'sys.student_id = students.id AND sys.school_year = student_class.school_year',
-                'left'
-            )
-            ->join(
+                'left',
+                false
+            );
+        }
+
+        if ($hasEnrollments) {
+            $builder->join(
                 'enrollments',
                 $this->latestEnrollmentJoinCondition($schoolYear),
                 'left',
                 false
-            )
-            ->whereIn(
-                'student_class.class_section_id',
-                $classSectionIds
             );
+        }
+
+        $builder->whereIn(
+            'student_class.class_section_id',
+            $classSectionIds
+        );
 
         if ($schoolYear !== '') {
             $builder->where(
@@ -492,7 +517,12 @@ class StudentClassModel extends Model
             );
         }
 
-        $this->includeActiveOrTerminalEnrollment($builder, $schoolYear);
+        $this->includeActiveOrTerminalEnrollment(
+            $builder,
+            $schoolYear,
+            $hasEnrollmentStatus,
+            $hasEnrollmentWithdrawn
+        );
 
         return $builder
             ->orderBy('students.lastname', 'ASC')