diff --git a/server/src/main/kotlin/ir/armor/tachidesk/database/DBMangaer.kt b/server/src/main/kotlin/ir/armor/tachidesk/database/DBMangaer.kt
index a379647f..d12efb22 100644
--- a/server/src/main/kotlin/ir/armor/tachidesk/database/DBMangaer.kt
+++ b/server/src/main/kotlin/ir/armor/tachidesk/database/DBMangaer.kt
@@ -23,10 +23,9 @@ object DBMangaer {
 }
 
 fun makeDataBaseTables() {
-    // mention db object to connect
-    DBMangaer.db
-//    val db = DBMangaer.db
-//    db.useNestedTransactions = true
+    // must mention db object so the lazy block executes
+    val db = DBMangaer.db
+    db.useNestedTransactions = true
 
     transaction {
         SchemaUtils.createMissingTablesAndColumns(
diff --git a/server/src/main/kotlin/ir/armor/tachidesk/util/Category.kt b/server/src/main/kotlin/ir/armor/tachidesk/util/Category.kt
index 37da061e..ae851b52 100644
--- a/server/src/main/kotlin/ir/armor/tachidesk/util/Category.kt
+++ b/server/src/main/kotlin/ir/armor/tachidesk/util/Category.kt
@@ -1,6 +1,7 @@
 package ir.armor.tachidesk.util
 
 import ir.armor.tachidesk.database.dataclass.CategoryDataClass
+import ir.armor.tachidesk.database.table.CategoryMangaTable
 import ir.armor.tachidesk.database.table.CategoryTable
 import ir.armor.tachidesk.database.table.toDataClass
 import org.jetbrains.exposed.sql.SortOrder
@@ -49,6 +50,9 @@ fun reorderCategory(categoryId: Int, from: Int, to: Int) {
 
 fun removeCategory(categoryId: Int) {
     transaction {
+        CategoryMangaTable.select { CategoryMangaTable.category eq categoryId }.forEach {
+            removeMangaFromCategory(it[CategoryMangaTable.manga].value, categoryId)
+        }
         CategoryTable.deleteWhere { CategoryTable.id eq categoryId }
     }
 }