Fix Flyway migration

backend/src/main/java/com/petshop/backend/config/FlywayContextInitializer.java

@@ -35,13 +35,14 @@ public class FlywayContextInitializer implements ApplicationContextInitializer<C
         RuntimeException lastFailure = null;
         for (int attempt = 1; attempt <= MAX_RETRIES; attempt++) {
             try {
-                Flyway.configure()
+                Flyway flyway = Flyway.configure()
                         .dataSource(url, username, password)
                         .locations(locations)
                         .baselineOnMigrate(environment.getProperty("spring.flyway.baseline-on-migrate", Boolean.class, false))
                         .baselineVersion(MigrationVersion.fromVersion(environment.getProperty("spring.flyway.baseline-version", "1")))
-                        .load()
-                        .migrate();
+                        .load();
+                flyway.repair();
+                flyway.migrate();
                 return;
             } catch (RuntimeException ex) {
                 lastFailure = ex;

backend/src/main/resources/db/migration/V18__past_appointments_missed.sql

@@ -11,12 +11,18 @@ WHERE LOWER(appointmentStatus) = 'booked'
   );
 
 -- Part 2: Resolve potential double-bookings caused by V15's simple backfill.
--- We try to spread overlapping appointments among other active staff in the same store.
--- This is a one-time cleanup for demo data integrity.
-
--- Temporary table to find conflicts (same employee, same date, overlapping time)
--- For simplicity in SQL, we just check exact same time for the demo data cleanup.
+-- MySQL Error 1093 workaround: wrap same-table subqueries in derived tables.
 UPDATE appointment a1
+JOIN (
+    SELECT a3.appointmentId
+    FROM appointment a3
+    INNER JOIN appointment a4
+        ON  a4.employeeId      = a3.employeeId
+        AND a4.appointmentDate = a3.appointmentDate
+        AND a4.appointmentTime = a3.appointmentTime
+        AND a4.appointmentId   < a3.appointmentId
+    WHERE LOWER(a3.appointmentStatus) NOT IN ('cancelled', 'missed')
+) conflicting ON conflicting.appointmentId = a1.appointmentId
 SET a1.employeeId = (
     SELECT es.employeeId
     FROM employeeStore es
@@ -25,21 +31,16 @@ SET a1.employeeId = (
     WHERE es.storeId = a1.storeId
       AND e.isActive = TRUE
       AND u.role = 'STAFF'
-      -- Find an employee who DOES NOT have an appointment at this exact time
       AND NOT EXISTS (
-          SELECT 1 FROM appointment a2 
-          WHERE a2.employeeId = es.employeeId 
-            AND a2.appointmentDate = a1.appointmentDate 
-            AND a2.appointmentTime = a1.appointmentTime
-            AND a2.appointmentId <> a1.appointmentId
+          SELECT 1 FROM (
+              SELECT employeeId, appointmentDate, appointmentTime, appointmentId
+              FROM appointment
+          ) snap
+          WHERE snap.employeeId      = es.employeeId
+            AND snap.appointmentDate = a1.appointmentDate
+            AND snap.appointmentTime = a1.appointmentTime
+            AND snap.appointmentId  <> a1.appointmentId
       )
     ORDER BY es.employeeId ASC
     LIMIT 1
-)
-WHERE EXISTS (
-    SELECT 1 FROM appointment a3
-    WHERE a3.employeeId = a1.employeeId
-      AND a3.appointmentDate = a1.appointmentDate
-      AND a3.appointmentTime = a1.appointmentTime
-      AND a3.appointmentId < a1.appointmentId
-) AND LOWER(a1.appointmentStatus) NOT IN ('cancelled', 'missed');
+);