diff --git a/database/gdb/gdb_model_select.go b/database/gdb/gdb_model_select.go
index 3e8ef3038..c7d98cdbc 100644
--- a/database/gdb/gdb_model_select.go
+++ b/database/gdb/gdb_model_select.go
@@ -42,10 +42,12 @@ func (m *Model) All(where ...interface{}) (Result, error) {
 		}
 		conditionWhere += softDeletingCondition
 	}
+	// DO NOT quote the m.fields where, in case of fields like:
+	// DISTINCT t.user_id uid
 	return m.doGetAll(
 		fmt.Sprintf(
 			"SELECT %s FROM %s%s",
-			m.db.QuoteString(m.fields),
+			m.fields,
 			m.tables,
 			conditionWhere+conditionExtra,
 		),
@@ -249,7 +251,9 @@ func (m *Model) Count(where ...interface{}) (int, error) {
 	}
 	countFields := "COUNT(1)"
 	if m.fields != "" && m.fields != "*" {
-		countFields = fmt.Sprintf(`COUNT(%s)`, m.db.QuoteString(m.fields))
+		// DO NOT quote the m.fields here, in case of fields like:
+		// DISTINCT t.user_id uid
+		countFields = fmt.Sprintf(`COUNT(%s)`, m.fields)
 	}
 	var (
 		softDeletingCondition                         = m.getConditionForSoftDeleting()
diff --git a/database/gdb/gdb_unit_z_mysql_model_test.go b/database/gdb/gdb_unit_z_mysql_model_test.go
index f37a9fd61..e4cf67f2d 100644
--- a/database/gdb/gdb_unit_z_mysql_model_test.go
+++ b/database/gdb/gdb_unit_z_mysql_model_test.go
@@ -2297,3 +2297,30 @@ func Test_Model_Having(t *testing.T) {
 		t.Assert(len(all), 1)
 	})
 }
+
+func Test_Model_Distinct(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		all, err := db.Table(table, "t").Fields("distinct t.id").Where("id > 1").Having("id > 8").All()
+		t.Assert(err, nil)
+		t.Assert(len(all), 2)
+	})
+}
+
+func Test_Model_Min_Max(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		value, err := db.Table(table, "t").Fields("min(t.id)").Where("id > 1").Value()
+		t.Assert(err, nil)
+		t.Assert(value.Int(), 2)
+	})
+	gtest.C(t, func(t *gtest.T) {
+		value, err := db.Table(table, "t").Fields("max(t.id)").Where("id > 1").Value()
+		t.Assert(err, nil)
+		t.Assert(value.Int(), 10)
+	})
+}
diff --git a/errors/gerror/gerror.go b/errors/gerror/gerror.go
index c9df839ec..11c6e55ba 100644
--- a/errors/gerror/gerror.go
+++ b/errors/gerror/gerror.go
@@ -11,15 +11,17 @@ import (
 	"fmt"
 )
 
+// ApiStack is the interface for Stack feature.
 type ApiStack interface {
 	Stack() string
 }
 
+// ApiCause is the interface for Cause feature.
 type ApiCause interface {
 	Cause() error
 }
 
-// New returns an error that formats as the given text.
+// New creates and returns an error which is formatted from given text.
 func New(text string) error {
 	if text == "" {
 		return nil
@@ -30,7 +32,7 @@ func New(text string) error {
 	}
 }
 
-// Newf returns an error that formats as the given text.
+// Newf returns an error that formats as the given format and args.
 func Newf(format string, args ...interface{}) error {
 	if format == "" {
 		return nil
@@ -56,7 +58,7 @@ func Wrap(err error, text string) error {
 
 // Wrapf returns an error annotating err with a stack trace
 // at the point Wrapf is called, and the format specifier.
-// It returns nil if given err is nil.
+// It returns nil if given <err> is nil.
 func Wrapf(err error, format string, args ...interface{}) error {
 	if err == nil {
 		return nil
@@ -68,7 +70,7 @@ func Wrapf(err error, format string, args ...interface{}) error {
 	}
 }
 
-// Cause returns the root cause error.
+// Cause returns the root cause error of <err>.
 func Cause(err error) error {
 	if err != nil {
 		if e, ok := err.(ApiCause); ok {
@@ -79,7 +81,7 @@ func Cause(err error) error {
 }
 
 // Stack returns the stack callers as string.
-// It returns an empty string id the <err> does not support stacks.
+// It returns an empty string if the <err> does not support stacks.
 func Stack(err error) string {
 	if err == nil {
 		return ""
diff --git a/errors/gerror/gerror_error.go b/errors/gerror/gerror_error.go
index 7a743014a..43a99a172 100644
--- a/errors/gerror/gerror_error.go
+++ b/errors/gerror/gerror_error.go
@@ -94,7 +94,7 @@ func (err *Error) Format(s fmt.State, verb rune) {
 }
 
 // Stack returns the stack callers as string.
-// It returns an empty string id the <err> does not support stacks.
+// It returns an empty string if the <err> does not support stacks.
 func (err *Error) Stack() string {
 	if err == nil {
 		return ""
diff --git a/errors/gerror/gerror_test.go b/errors/gerror/gerror_test.go
index e89662638..9b7346ce9 100644
--- a/errors/gerror/gerror_test.go
+++ b/errors/gerror/gerror_test.go
@@ -15,10 +15,6 @@ import (
 	"github.com/gogf/gf/test/gtest"
 )
 
-func interfaceNil() interface{} {
-	return nil
-}
-
 func nilError() error {
 	return nil
 }