diff --git a/src/core/qgssqliteexpressioncompiler.cpp b/src/core/qgssqliteexpressioncompiler.cpp
index ee801c27537..803532385cd 100644
--- a/src/core/qgssqliteexpressioncompiler.cpp
+++ b/src/core/qgssqliteexpressioncompiler.cpp
@@ -92,7 +92,12 @@ static const QMap<QString, QString>& functionNamesSqlFunctionsMap()
     fnNames =
     {
       { "abs", "abs" },
-      { "round", "round" }
+      { "char", "char" },
+      { "coalesce", "coalesce" },
+      { "lower", "lower" },
+      { "round", "round" },
+      { "trim", "trim" },
+      { "upper", "upper" },
     };
   }
   return fnNames;
diff --git a/src/providers/postgres/qgspostgresexpressioncompiler.cpp b/src/providers/postgres/qgspostgresexpressioncompiler.cpp
index 3fabf4aab65..d4ffa4a27d1 100644
--- a/src/providers/postgres/qgspostgresexpressioncompiler.cpp
+++ b/src/providers/postgres/qgspostgresexpressioncompiler.cpp
@@ -102,7 +102,12 @@ static const QMap<QString, QString>& functionNamesSqlFunctionsMap()
       { "union", "ST_Union" },
 #endif
       { "geom_from_wkt", "ST_GeomFromText" },
-      { "geom_from_gml", "ST_GeomFromGML" }
+      { "geom_from_gml", "ST_GeomFromGML" },
+      { "char", "chr" },
+      { "coalesce", "coalesce" },
+      { "lower", "lower" },
+      { "trim", "trim" },
+      { "upper", "upper" },
     };
   }
   return fnNames;
diff --git a/tests/src/python/providertestbase.py b/tests/src/python/providertestbase.py
index 9490feef470..8309ccd968e 100644
--- a/tests/src/python/providertestbase.py
+++ b/tests/src/python/providertestbase.py
@@ -252,6 +252,11 @@ class ProviderTestCase(object):
         self.assert_query(provider, 'floor(cnt / 66.67) <= 2', [1, 2, 5])
         self.assert_query(provider, 'ceil(cnt / 66.67) <= 2', [1, 5])
         self.assert_query(provider, 'pk < pi() / 2', [1])
+        self.assert_query(provider, 'pk = char(51)', [3])
+        self.assert_query(provider, 'pk = coalesce(NULL,3,4)', [3])
+        self.assert_query(provider, 'lower(name) = \'apple\'', [2])
+        self.assert_query(provider, 'upper(name) = \'APPLE\'', [2])
+        self.assert_query(provider, 'name = trim(\'   Apple   \')', [2])
 
         # geometry
         # azimuth and touches tests are deactivated because they do not pass for WFS provider
diff --git a/tests/src/python/test_provider_shapefile.py b/tests/src/python/test_provider_shapefile.py
index 7b11b42a68a..c6f876562d7 100644
--- a/tests/src/python/test_provider_shapefile.py
+++ b/tests/src/python/test_provider_shapefile.py
@@ -155,6 +155,11 @@ class TestPyQgsShapefileProvider(unittest.TestCase, ProviderTestCase):
                        'floor(cnt / 66.67) <= 2',
                        'ceil(cnt / 66.67) <= 2',
                        'pk < pi() / 2',
+                       'pk = char(51)',
+                       'pk = coalesce(NULL,3,4)',
+                       'lower(name) = \'apple\'',
+                       'upper(name) = \'APPLE\'',
+                       'name = trim(\'   Apple   \')',
                        'x($geometry) < -70',
                        'y($geometry) > 70',
                        'xmin($geometry) < -70',