diff --git a/database/gdb/gdb_core_utility.go b/database/gdb/gdb_core_utility.go
index 87add6748..5b0f1973a 100644
--- a/database/gdb/gdb_core_utility.go
+++ b/database/gdb/gdb_core_utility.go
@@ -31,6 +31,7 @@ func (c *Core) SlaveLink(schema ...string) (Link, error) {
 
 // QuoteWord checks given string `s` a word, if true quotes it with security chars of the database
 // and returns the quoted string; or else return `s` without any change.
+// The meaning of a `word` can be considered as a column name.
 func (c *Core) QuoteWord(s string) string {
 	charLeft, charRight := c.db.GetChars()
 	return doQuoteWord(s, charLeft, charRight)
@@ -38,6 +39,7 @@ func (c *Core) QuoteWord(s string) string {
 
 // QuoteString quotes string with quote chars. Strings like:
 // "user", "user u", "user,user_detail", "user u, user_detail ut", "u.id asc".
+// The meaning of a `string` can be considered as part of a statement string including columns.
 func (c *Core) QuoteString(s string) string {
 	charLeft, charRight := c.db.GetChars()
 	return doQuoteString(s, charLeft, charRight)
diff --git a/database/gdb/gdb_model.go b/database/gdb/gdb_model.go
index a9d1fe2dd..fe761dca1 100644
--- a/database/gdb/gdb_model.go
+++ b/database/gdb/gdb_model.go
@@ -73,6 +73,7 @@ const (
 	whereHolderOperatorWhere = 1
 	whereHolderOperatorAnd   = 2
 	whereHolderOperatorOr    = 3
+	defaultFields            = "*"
 )
 
 // Table is alias of Core.Model.
@@ -130,7 +131,7 @@ func (c *Core) Model(tableNameQueryOrStruct ...interface{}) *Model {
 		db:         c.db,
 		tablesInit: tableStr,
 		tables:     tableStr,
-		fields:     "*",
+		fields:     defaultFields,
 		start:      -1,
 		offset:     -1,
 		filter:     true,
diff --git a/database/gdb/gdb_model_condition.go b/database/gdb/gdb_model_condition.go
index 933c3ede9..5853fe7df 100644
--- a/database/gdb/gdb_model_condition.go
+++ b/database/gdb/gdb_model_condition.go
@@ -237,10 +237,13 @@ func (m *Model) WhereOrNotNull(columns ...string) *Model {
 }
 
 // Group sets the "GROUP BY" statement for the model.
-func (m *Model) Group(groupBy string) *Model {
-	model := m.getModel()
-	model.groupBy = m.db.GetCore().QuoteString(groupBy)
-	return model
+func (m *Model) Group(groupBy ...string) *Model {
+	if len(groupBy) > 0 {
+		model := m.getModel()
+		model.groupBy = m.db.GetCore().QuoteString(gstr.Join(groupBy, ","))
+		return model
+	}
+	return m
 }
 
 // And adds "AND" condition to the where statement.
diff --git a/database/gdb/gdb_model_fields.go b/database/gdb/gdb_model_fields.go
index 1d3b8a626..a4115039e 100644
--- a/database/gdb/gdb_model_fields.go
+++ b/database/gdb/gdb_model_fields.go
@@ -14,7 +14,7 @@ import (
 	"github.com/gogf/gf/util/gutil"
 )
 
-// Fields sets the operation fields of the model, multiple fields joined using char ','.
+// Fields appends `fieldNamesOrMapStruct` to the operation fields of the model, multiple fields joined using char ','.
 // The parameter `fieldNamesOrMapStruct` can be type of string/map/*map/struct/*struct.
 func (m *Model) Fields(fieldNamesOrMapStruct ...interface{}) *Model {
 	length := len(fieldNamesOrMapStruct)
@@ -24,26 +24,32 @@ func (m *Model) Fields(fieldNamesOrMapStruct ...interface{}) *Model {
 	switch {
 	// String slice.
 	case length >= 2:
-		model := m.getModel()
-		model.fields = gstr.Join(m.mappingAndFilterToTableFields(gconv.Strings(fieldNamesOrMapStruct), true), ",")
-		return model
-	// It need type asserting.
+		return m.appendFieldsByStr(gstr.Join(
+			m.mappingAndFilterToTableFields(gconv.Strings(fieldNamesOrMapStruct), true),
+			",",
+		))
+	// It needs type asserting.
 	case length == 1:
-		model := m.getModel()
 		switch r := fieldNamesOrMapStruct[0].(type) {
 		case string:
-			model.fields = gstr.Join(m.mappingAndFilterToTableFields([]string{r}, false), ",")
+			return m.appendFieldsByStr(gstr.Join(
+				m.mappingAndFilterToTableFields([]string{r}, false), ",",
+			))
 		case []string:
-			model.fields = gstr.Join(m.mappingAndFilterToTableFields(r, true), ",")
+			return m.appendFieldsByStr(gstr.Join(
+				m.mappingAndFilterToTableFields(r, true), ",",
+			))
 		default:
-			model.fields = gstr.Join(m.mappingAndFilterToTableFields(gutil.Keys(r), true), ",")
+			return m.appendFieldsByStr(gstr.Join(
+				m.mappingAndFilterToTableFields(gutil.Keys(r), true), ",",
+			))
 		}
-		return model
 	}
 	return m
 }
 
-// FieldsEx sets the excluded operation fields of the model, multiple fields joined using char ','.
+// FieldsEx appends `fieldNamesOrMapStruct` to the excluded operation fields of the model,
+// multiple fields joined using char ','.
 // Note that this function supports only single table operations.
 // The parameter `fieldNamesOrMapStruct` can be type of string/map/*map/struct/*struct.
 func (m *Model) FieldsEx(fieldNamesOrMapStruct ...interface{}) *Model {
@@ -70,6 +76,78 @@ func (m *Model) FieldsEx(fieldNamesOrMapStruct ...interface{}) *Model {
 	return m
 }
 
+// FieldCount formats and appends commonly used field `COUNT(column)` to the select fields of model.
+func (m *Model) FieldCount(column string, as ...string) *Model {
+	asStr := ""
+	if len(as) > 0 && as[0] != "" {
+		asStr = fmt.Sprintf(` AS %s`, m.db.GetCore().QuoteWord(as[0]))
+	}
+	return m.appendFieldsByStr(fmt.Sprintf(`COUNT(%s)%s`, m.db.GetCore().QuoteWord(column), asStr))
+}
+
+// FieldSum formats and appends commonly used field `SUM(column)` to the select fields of model.
+func (m *Model) FieldSum(column string, as ...string) *Model {
+	asStr := ""
+	if len(as) > 0 && as[0] != "" {
+		asStr = fmt.Sprintf(` AS %s`, m.db.GetCore().QuoteWord(as[0]))
+	}
+	return m.appendFieldsByStr(fmt.Sprintf(`SUM(%s)%s`, m.db.GetCore().QuoteWord(column), asStr))
+}
+
+// FieldMin formats and appends commonly used field `MIN(column)` to the select fields of model.
+func (m *Model) FieldMin(column string, as ...string) *Model {
+	asStr := ""
+	if len(as) > 0 && as[0] != "" {
+		asStr = fmt.Sprintf(` AS %s`, m.db.GetCore().QuoteWord(as[0]))
+	}
+	return m.appendFieldsByStr(fmt.Sprintf(`MIN(%s)%s`, m.db.GetCore().QuoteWord(column), asStr))
+}
+
+// FieldMax formats and appends commonly used field `MAX(column)` to the select fields of model.
+func (m *Model) FieldMax(column string, as ...string) *Model {
+	asStr := ""
+	if len(as) > 0 && as[0] != "" {
+		asStr = fmt.Sprintf(` AS %s`, m.db.GetCore().QuoteWord(as[0]))
+	}
+	return m.appendFieldsByStr(fmt.Sprintf(`MAX(%s)%s`, m.db.GetCore().QuoteWord(column), asStr))
+}
+
+// FieldAvg formats and appends commonly used field `AVG(column)` to the select fields of model.
+func (m *Model) FieldAvg(column string, as ...string) *Model {
+	asStr := ""
+	if len(as) > 0 && as[0] != "" {
+		asStr = fmt.Sprintf(` AS %s`, m.db.GetCore().QuoteWord(as[0]))
+	}
+	return m.appendFieldsByStr(fmt.Sprintf(`AVG(%s)%s`, m.db.GetCore().QuoteWord(column), asStr))
+}
+
+func (m *Model) appendFieldsByStr(fields string) *Model {
+	if fields != "" {
+		model := m.getModel()
+		if model.fields == defaultFields {
+			model.fields = ""
+		}
+		if model.fields != "" {
+			model.fields += ","
+		}
+		model.fields += fields
+		return model
+	}
+	return m
+}
+
+func (m *Model) appendFieldsExByStr(fieldsEx string) *Model {
+	if fieldsEx != "" {
+		model := m.getModel()
+		if model.fieldsEx != "" {
+			model.fieldsEx += ","
+		}
+		model.fieldsEx += fieldsEx
+		return model
+	}
+	return m
+}
+
 // Filter marks filtering the fields which does not exist in the fields of the operated table.
 // Note that this function supports only single table operations.
 // Deprecated, filter feature is automatically enabled from GoFrame v1.16.0, it is so no longer used.
diff --git a/database/gdb/gdb_z_mysql_model_test.go b/database/gdb/gdb_z_mysql_model_test.go
index ea4e32049..806cc80bc 100644
--- a/database/gdb/gdb_z_mysql_model_test.go
+++ b/database/gdb/gdb_z_mysql_model_test.go
@@ -3768,3 +3768,55 @@ func Test_Model_Handler(t *testing.T) {
 		t.Assert(all[2]["id"], 4)
 	})
 }
+
+func Test_Model_FieldCount(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		all, err := db.Model(table).Fields("id").FieldCount("id", "total").Group("id").OrderAsc("id").All()
+		t.AssertNil(err)
+		t.Assert(len(all), TableSize)
+		t.Assert(all[0]["id"], 1)
+		t.Assert(all[0]["total"], 1)
+	})
+}
+
+func Test_Model_FieldMax(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		all, err := db.Model(table).Fields("id").FieldMax("id", "total").Group("id").OrderAsc("id").All()
+		t.AssertNil(err)
+		t.Assert(len(all), TableSize)
+		t.Assert(all[0]["id"], 1)
+		t.Assert(all[0]["total"], 1)
+	})
+}
+
+func Test_Model_FieldMin(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		all, err := db.Model(table).Fields("id").FieldMin("id", "total").Group("id").OrderAsc("id").All()
+		t.AssertNil(err)
+		t.Assert(len(all), TableSize)
+		t.Assert(all[0]["id"], 1)
+		t.Assert(all[0]["total"], 1)
+	})
+}
+
+func Test_Model_FieldAvg(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		all, err := db.Model(table).Fields("id").FieldAvg("id", "total").Group("id").OrderAsc("id").All()
+		t.AssertNil(err)
+		t.Assert(len(all), TableSize)
+		t.Assert(all[0]["id"], 1)
+		t.Assert(all[0]["total"], 1)
+	})
+}
diff --git a/net/ghttp/ghttp_request_middleware.go b/net/ghttp/ghttp_request_middleware.go
index 8554b4f3f..66dc66275 100644
--- a/net/ghttp/ghttp_request_middleware.go
+++ b/net/ghttp/ghttp_request_middleware.go
@@ -153,13 +153,17 @@ func (m *middleware) callHandlerFunc(funcInfo handlerFuncInfo) {
 			switch len(results) {
 			case 1:
 				if !results[0].IsNil() {
-					m.request.handlerResponse.Error = results[0].Interface().(error)
+					if err, ok := results[0].Interface().(error); ok {
+						m.request.handlerResponse.Error = err
+					}
 				}
 
 			case 2:
 				m.request.handlerResponse.Object = results[0].Interface()
 				if !results[1].IsNil() {
-					m.request.handlerResponse.Error = results[1].Interface().(error)
+					if err, ok := results[1].Interface().(error); ok {
+						m.request.handlerResponse.Error = err
+					}
 				}
 			}
 		}
diff --git a/util/gvalid/gvalid.go b/util/gvalid/gvalid.go
index 24160e741..a035b9337 100644
--- a/util/gvalid/gvalid.go
+++ b/util/gvalid/gvalid.go
@@ -24,9 +24,9 @@ import (
 // required-if          format: required-if:field,value,...           brief: Required unless all given field and its value are equal.
 // required-unless      format: required-unless:field,value,...       brief: Required unless all given field and its value are not equal.
 // required-with        format: required-with:field1,field2,...       brief: Required if any of given fields are not empty.
-// required-with-all    format: required-with-all:field1,field2,...   brief: Required if all of given fields are not empty.
+// required-with-all    format: required-with-all:field1,field2,...   brief: Required if all given fields are not empty.
 // required-without     format: required-without:field1,field2,...    brief: Required if any of given fields are empty.
-// required-without-all format: required-without-all:field1,field2,...brief: Required if all of given fields are empty.
+// required-without-all format: required-without-all:field1,field2,...brief: Required if all given fields are empty.
 // bail                 format: bail                                  brief: Stop validating when this field's validation failed.
 // date                 format: date                                  brief: Standard date, like: 2006-01-02, 20060102, 2006.01.02
 // date-format          format: date-format:format                    brief: Custom date format.