diff --git a/association.go b/association.go
index 14fd1c35..c36a31b7 100644
--- a/association.go
+++ b/association.go
@@ -86,7 +86,7 @@ func (association *Association) Replace(values ...interface{}) *Association {
 				}
 			}
 
-			newPrimaryKeys := scope.getColumnAsArray(associationForeignFieldNames, field.Interface())
+			newPrimaryKeys := scope.getColumnAsArrayUnique(associationForeignFieldNames, field.Interface())
 
 			if len(newPrimaryKeys) > 0 {
 				sql := fmt.Sprintf("%v NOT IN (%v)", toQueryCondition(scope, associationForeignDBNames), toQueryMarks(newPrimaryKeys))
@@ -104,7 +104,7 @@ func (association *Association) Replace(values ...interface{}) *Association {
 				}
 			}
 
-			if sourcePrimaryKeys := scope.getColumnAsArray(sourceForeignFieldNames, scope.Value); len(sourcePrimaryKeys) > 0 {
+			if sourcePrimaryKeys := scope.getColumnAsArrayUnique(sourceForeignFieldNames, scope.Value); len(sourcePrimaryKeys) > 0 {
 				newDB = newDB.Where(fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, relationship.ForeignDBNames), toQueryMarks(sourcePrimaryKeys)), toQueryValues(sourcePrimaryKeys)...)
 
 				association.setErr(relationship.JoinTableHandler.Delete(relationship.JoinTableHandler, newDB, relationship))
@@ -149,7 +149,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 		deletingResourcePrimaryDBNames = append(deletingResourcePrimaryDBNames, field.DBName)
 	}
 
-	deletingPrimaryKeys := scope.getColumnAsArray(deletingResourcePrimaryFieldNames, values...)
+	deletingPrimaryKeys := scope.getColumnAsArrayUnique(deletingResourcePrimaryFieldNames, values...)
 
 	if relationship.Kind == "many_to_many" {
 		// source value's foreign keys
@@ -169,7 +169,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 		}
 
 		// association value's foreign keys
-		deletingPrimaryKeys := scope.getColumnAsArray(associationForeignFieldNames, values...)
+		deletingPrimaryKeys := scope.getColumnAsArrayUnique(associationForeignFieldNames, values...)
 		sql := fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, relationship.AssociationForeignDBNames), toQueryMarks(deletingPrimaryKeys))
 		newDB = newDB.Where(sql, toQueryValues(deletingPrimaryKeys)...)
 
@@ -182,7 +182,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 
 		if relationship.Kind == "belongs_to" {
 			// find with deleting relation's foreign keys
-			primaryKeys := scope.getColumnAsArray(relationship.AssociationForeignFieldNames, values...)
+			primaryKeys := scope.getColumnAsArrayUnique(relationship.AssociationForeignFieldNames, values...)
 			newDB = newDB.Where(
 				fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, relationship.ForeignDBNames), toQueryMarks(primaryKeys)),
 				toQueryValues(primaryKeys)...,
@@ -199,7 +199,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 			}
 		} else if relationship.Kind == "has_one" || relationship.Kind == "has_many" {
 			// find all relations
-			primaryKeys := scope.getColumnAsArray(relationship.AssociationForeignFieldNames, scope.Value)
+			primaryKeys := scope.getColumnAsArrayUnique(relationship.AssociationForeignFieldNames, scope.Value)
 			newDB = newDB.Where(
 				fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, relationship.ForeignDBNames), toQueryMarks(primaryKeys)),
 				toQueryValues(primaryKeys)...,
@@ -224,7 +224,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 
 			for i := 0; i < field.Len(); i++ {
 				reflectValue := field.Index(i)
-				primaryKey := scope.getColumnAsArray(deletingResourcePrimaryFieldNames, reflectValue.Interface())[0]
+				primaryKey := scope.getColumnAsArrayUnique(deletingResourcePrimaryFieldNames, reflectValue.Interface())[0]
 				var isDeleted = false
 				for _, pk := range deletingPrimaryKeys {
 					if equalAsString(primaryKey, pk) {
@@ -239,7 +239,7 @@ func (association *Association) Delete(values ...interface{}) *Association {
 
 			association.field.Set(leftValues)
 		} else if field.Kind() == reflect.Struct {
-			primaryKey := scope.getColumnAsArray(deletingResourcePrimaryFieldNames, field.Interface())[0]
+			primaryKey := scope.getColumnAsArrayUnique(deletingResourcePrimaryFieldNames, field.Interface())[0]
 			for _, pk := range deletingPrimaryKeys {
 				if equalAsString(primaryKey, pk) {
 					association.field.Set(reflect.Zero(field.Type()))
@@ -270,13 +270,13 @@ func (association *Association) Count() int {
 	if relationship.Kind == "many_to_many" {
 		query = relationship.JoinTableHandler.JoinWith(relationship.JoinTableHandler, query, scope.Value)
 	} else if relationship.Kind == "has_many" || relationship.Kind == "has_one" {
-		primaryKeys := scope.getColumnAsArray(relationship.AssociationForeignFieldNames, scope.Value)
+		primaryKeys := scope.getColumnAsArrayUnique(relationship.AssociationForeignFieldNames, scope.Value)
 		query = query.Where(
 			fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, relationship.ForeignDBNames), toQueryMarks(primaryKeys)),
 			toQueryValues(primaryKeys)...,
 		)
 	} else if relationship.Kind == "belongs_to" {
-		primaryKeys := scope.getColumnAsArray(relationship.ForeignFieldNames, scope.Value)
+		primaryKeys := scope.getColumnAsArrayUnique(relationship.ForeignFieldNames, scope.Value)
 		query = query.Where(
 			fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, relationship.AssociationForeignDBNames), toQueryMarks(primaryKeys)),
 			toQueryValues(primaryKeys)...,
diff --git a/callback_query_preload.go b/callback_query_preload.go
index fff252c9..393390a6 100644
--- a/callback_query_preload.go
+++ b/callback_query_preload.go
@@ -126,7 +126,7 @@ func (scope *Scope) handleHasOnePreload(field *Field, conditions []interface{})
 	relation := field.Relationship
 
 	// get relations's primary keys
-	primaryKeys := scope.getColumnAsArray(relation.AssociationForeignFieldNames, scope.Value)
+	primaryKeys := scope.getColumnAsArrayUnique(relation.AssociationForeignFieldNames, scope.Value)
 	if len(primaryKeys) == 0 {
 		return
 	}
@@ -175,7 +175,7 @@ func (scope *Scope) handleHasManyPreload(field *Field, conditions []interface{})
 	relation := field.Relationship
 
 	// get relations's primary keys
-	primaryKeys := scope.getColumnAsArray(relation.AssociationForeignFieldNames, scope.Value)
+	primaryKeys := scope.getColumnAsArrayUnique(relation.AssociationForeignFieldNames, scope.Value)
 	if len(primaryKeys) == 0 {
 		return
 	}
@@ -231,7 +231,7 @@ func (scope *Scope) handleBelongsToPreload(field *Field, conditions []interface{
 	preloadDB, preloadConditions := scope.generatePreloadDBWithConditions(conditions)
 
 	// get relations's primary keys
-	primaryKeys := scope.getColumnAsArray(relation.ForeignFieldNames, scope.Value)
+	primaryKeys := scope.getColumnAsArrayUnique(relation.ForeignFieldNames, scope.Value)
 	if len(primaryKeys) == 0 {
 		return
 	}
diff --git a/join_table_handler.go b/join_table_handler.go
index 18c12a85..a0bef0a3 100644
--- a/join_table_handler.go
+++ b/join_table_handler.go
@@ -178,7 +178,7 @@ func (s JoinTableHandler) JoinWith(handler JoinTableHandlerInterface, db *DB, so
 			}
 		}
 
-		foreignFieldValues := scope.getColumnAsArray(foreignFieldNames, scope.Value)
+		foreignFieldValues := scope.getColumnAsArrayUnique(foreignFieldNames, scope.Value)
 
 		var condString string
 		if len(foreignFieldValues) > 0 {
@@ -189,7 +189,7 @@ func (s JoinTableHandler) JoinWith(handler JoinTableHandlerInterface, db *DB, so
 
 			condString = fmt.Sprintf("%v IN (%v)", toQueryCondition(scope, quotedForeignDBNames), toQueryMarks(foreignFieldValues))
 
-			keys := scope.getColumnAsArray(foreignFieldNames, scope.Value)
+			keys := scope.getColumnAsArrayUnique(foreignFieldNames, scope.Value)
 			values = append(values, toQueryValues(keys))
 		} else {
 			condString = fmt.Sprintf("1 <> 1")
diff --git a/scope.go b/scope.go
index 9a237998..47a768f3 100644
--- a/scope.go
+++ b/scope.go
@@ -1270,6 +1270,40 @@ func (scope *Scope) getColumnAsArray(columns []string, values ...interface{}) (r
 	return
 }
 
+func (scope *Scope) getColumnAsArrayUnique(columns []string, values ...interface{}) (results [][]interface{}) {
+	unfilteredResults := scope.getColumnAsArray(columns, values...)
+
+	rootMap := map[interface{}]interface{}{}
+
+	for _, valueSet := range unfilteredResults {
+		currentMap := rootMap
+		appendResult := false
+
+		for _, value := range valueSet {
+			if isBlank(reflect.ValueOf(value)) {
+				appendResult = false
+				break
+			}
+
+			innerMap, ok := currentMap[value]
+			if !ok {
+				innerMap = map[interface{}]interface{}{}
+				currentMap[value] = innerMap
+
+				appendResult = true
+			}
+
+			currentMap = innerMap.(map[interface{}]interface{})
+		}
+
+		if appendResult {
+			results = append(results, valueSet)
+		}
+	}
+
+	return
+}
+
 func (scope *Scope) getColumnAsScope(column string) *Scope {
 	indirectScopeValue := scope.IndirectValue()