diff --git a/frappe/query_builder/utils.py b/frappe/query_builder/utils.py
index d8e5698e66..e2276e15c0 100644
--- a/frappe/query_builder/utils.py
+++ b/frappe/query_builder/utils.py
@@ -11,7 +11,6 @@ class db_type(Enum):
 	MARIADB = "mariadb"
 	POSTGRES = "postgres"
 
-
 class ImportMapper:
 	def __init__(self, func_map: Dict[db_type, Callable]) -> None:
 		self.func_map = func_map
@@ -32,7 +31,7 @@ def get_query_builder(type_of_db: Optional[str]) -> Query:
 	Returns:
 		Query: [Query object]
 	"""
-	db = db_type["MARIADB"]
+	db = db_type.MARIADB
 	if type_of_db:
 		db = db_type(type_of_db)
 	selecter = {db_type.MARIADB: MariaDB, db_type.POSTGRES: Postgres}
diff --git a/frappe/tests/test_query_builder.py b/frappe/tests/test_query_builder.py
new file mode 100644
index 0000000000..6cbd3b2950
--- /dev/null
+++ b/frappe/tests/test_query_builder.py
@@ -0,0 +1,35 @@
+import unittest
+from typing import Callable
+
+import frappe
+from frappe.query_builder.functions import GroupConcat, Match
+from frappe.query_builder.utils import db_type
+
+
+def CheckDB(dbtype: db_type) -> Callable:
+	return unittest.skipIf(
+		db_type(frappe.conf.db_type) != dbtype, f"Only runs for{db_type}"
+	)
+
+@CheckDB(dbtype=db_type.MARIADB)
+class TestCustomFunctionsMariaDB(unittest.TestCase):
+	def test_concat(self):
+		self.assertEqual("GROUP_CONCAT('Notes')", GroupConcat("Notes").get_sql())
+
+	def test_match(self):
+		query = Match("Notes").Against("text")
+		self.assertEqual(
+			" MATCH('Notes') AGAINST ('+text*' IN BOOLEAN MODE)", query.get_sql()
+		)
+
+
+@CheckDB(dbtype=db_type.POSTGRES)
+class TestCustomFunctionsPostgres(unittest.TestCase):
+	def test_concat(self):
+		self.assertEqual("STRING_AGG('Notes',',')", GroupConcat("Notes").get_sql())
+
+	def test_match(self):
+		query = Match("Notes").Against("text")
+		self.assertEqual(
+			"TO_TSVECTOR('Notes') @@ PLAINTO_TSQUERY('text')", query.get_sql()
+		)