diff --git a/store/db/postgres/memo_organizer.go b/store/db/postgres/memo_organizer.go
index 2a85d5a1..4c9b9188 100644
--- a/store/db/postgres/memo_organizer.go
+++ b/store/db/postgres/memo_organizer.go
@@ -11,24 +11,14 @@ import (
 )
 
 func (d *DB) UpsertMemoOrganizer(ctx context.Context, upsert *store.MemoOrganizer) (*store.MemoOrganizer, error) {
-	pinnedValue := 0
+	pinned := 0
 	if upsert.Pinned {
-		pinnedValue = 1
+		pinned = 1
 	}
-	qb := squirrel.Insert("memo_organizer").
-		Columns("memo_id", "user_id", "pinned").
-		Values(upsert.MemoID, upsert.UserID, pinnedValue).
-		PlaceholderFormat(squirrel.Dollar)
-
-	stmt, args, err := qb.ToSql()
-	if err != nil {
+	stmt := "INSERT INTO memo_organizer (memo_id, user_id, pinned) VALUES ($1, $2, $3) ON CONFLICT (memo_id, user_id) DO UPDATE SET pinned = $4"
+	if _, err := d.db.ExecContext(ctx, stmt, upsert.MemoID, upsert.UserID, pinned, pinned); err != nil {
 		return nil, err
 	}
-
-	if _, err = d.db.ExecContext(ctx, stmt, args...); err != nil {
-		return nil, err
-	}
-
 	return upsert, nil
 }
 
diff --git a/store/db/postgres/memo_relation.go b/store/db/postgres/memo_relation.go
index fd62f483..a5c8b11f 100644
--- a/store/db/postgres/memo_relation.go
+++ b/store/db/postgres/memo_relation.go
@@ -14,6 +14,7 @@ func (d *DB) UpsertMemoRelation(ctx context.Context, create *store.MemoRelation)
 	qb := squirrel.Insert("memo_relation").
 		Columns("memo_id", "related_memo_id", "type").
 		Values(create.MemoID, create.RelatedMemoID, create.Type).
+		Suffix("ON CONFLICT (version) DO NOTHING").
 		PlaceholderFormat(squirrel.Dollar)
 
 	stmt, args, err := qb.ToSql()
diff --git a/store/db/postgres/migration_history.go b/store/db/postgres/migration_history.go
index 83279ec8..d7b8a665 100644
--- a/store/db/postgres/migration_history.go
+++ b/store/db/postgres/migration_history.go
@@ -44,9 +44,10 @@ func (d *DB) UpsertMigrationHistory(ctx context.Context, upsert *store.UpsertMig
 	qb := squirrel.Insert("migration_history").
 		Columns("version").
 		Values(upsert.Version).
-		Suffix("ON CONFLICT (version) DO UPDATE SET version = ?", upsert.Version)
+		Suffix("ON CONFLICT (version) DO NOTHING").
+		PlaceholderFormat(squirrel.Dollar)
 
-	query, args, err := qb.PlaceholderFormat(squirrel.Dollar).ToSql()
+	query, args, err := qb.ToSql()
 	if err != nil {
 		return nil, err
 	}
diff --git a/store/db/postgres/system_setting.go b/store/db/postgres/system_setting.go
index 4c42198d..9ad629bf 100644
--- a/store/db/postgres/system_setting.go
+++ b/store/db/postgres/system_setting.go
@@ -11,9 +11,11 @@ import (
 func (d *DB) UpsertSystemSetting(ctx context.Context, upsert *store.SystemSetting) (*store.SystemSetting, error) {
 	qb := squirrel.Insert("system_setting").
 		Columns("name", "value", "description").
-		Values(upsert.Name, upsert.Value, upsert.Description)
+		Values(upsert.Name, upsert.Value, upsert.Description).
+		Suffix("ON CONFLICT (name) DO UPDATE SET value = EXCLUDED.value, description = EXCLUDED.description").
+		PlaceholderFormat(squirrel.Dollar)
 
-	query, args, err := qb.PlaceholderFormat(squirrel.Dollar).ToSql()
+	query, args, err := qb.ToSql()
 	if err != nil {
 		return nil, err
 	}
diff --git a/store/db/postgres/tag.go b/store/db/postgres/tag.go
index c4218048..9097e8fb 100644
--- a/store/db/postgres/tag.go
+++ b/store/db/postgres/tag.go
@@ -11,20 +11,10 @@ import (
 )
 
 func (d *DB) UpsertTag(ctx context.Context, upsert *store.Tag) (*store.Tag, error) {
-	builder := squirrel.Insert("tag").
-		Columns("name", "creator_id").
-		Values(upsert.Name, upsert.CreatorID). // on conflict is not necessary, as only the pair of name and creator_id is unique
-		PlaceholderFormat(squirrel.Dollar)
-
-	query, args, err := builder.ToSql()
-	if err != nil {
+	stmt := "INSERT INTO tag (name, creator_id) VALUES ($1, $2) ON CONFLICT (name, creator_id) DO UPDATE SET name = $3"
+	if _, err := d.db.ExecContext(ctx, stmt, upsert.Name, upsert.CreatorID, upsert.Name); err != nil {
 		return nil, err
 	}
-
-	if _, err := d.db.ExecContext(ctx, query, args...); err != nil {
-		return nil, err
-	}
-
 	return upsert, nil
 }