diff --git a/convert/interface.go b/convert/interface.go
new file mode 100644
index 00000000..2b055253
--- /dev/null
+++ b/convert/interface.go
@@ -0,0 +1,48 @@
+// Copyright 2021 The Xorm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package convert
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+func Interface2Interface(userLocation *time.Location, v interface{}) (interface{}, error) {
+	if v == nil {
+		return nil, nil
+	}
+	switch vv := v.(type) {
+	case *int64:
+		return *vv, nil
+	case *int8:
+		return *vv, nil
+	case *sql.NullString:
+		return vv.String, nil
+	case *sql.RawBytes:
+		if len([]byte(*vv)) > 0 {
+			return []byte(*vv), nil
+		}
+		return nil, nil
+	case *sql.NullInt32:
+		return vv.Int32, nil
+	case *sql.NullInt64:
+		return vv.Int64, nil
+	case *sql.NullFloat64:
+		return vv.Float64, nil
+	case *sql.NullBool:
+		if vv.Valid {
+			return vv.Bool, nil
+		}
+		return nil, nil
+	case *sql.NullTime:
+		if vv.Valid {
+			return vv.Time.In(userLocation).Format("2006-01-02 15:04:05"), nil
+		}
+		return "", nil
+	default:
+		return "", fmt.Errorf("convert assign string unsupported type: %#v", vv)
+	}
+}
diff --git a/dialects/postgres.go b/dialects/postgres.go
index 9a5beddb..e4641509 100644
--- a/dialects/postgres.go
+++ b/dialects/postgres.go
@@ -1384,18 +1384,21 @@ func (p *pqDriver) GenScanResult(colType string) (interface{}, error) {
 	case "BIGINT":
 		var s sql.NullInt64
 		return &s, nil
-	case "TINYINT", "INT":
+	case "TINYINT", "INT", "INT8", "INT4":
 		var s sql.NullInt32
 		return &s, nil
-	case "FLOAT":
+	case "FLOAT", "FLOAT4":
 		var s sql.NullFloat64
 		return &s, nil
-	case "DATETIME":
+	case "DATETIME", "TIMESTAMP":
 		var s sql.NullTime
 		return &s, nil
 	case "BIT":
 		var s sql.RawBytes
 		return &s, nil
+	case "BOOL":
+		var s sql.NullBool
+		return &s, nil
 	default:
 		fmt.Printf("unknow postgres database type: %v\n", colType)
 		var r sql.RawBytes
diff --git a/scan.go b/scan.go
index d5b5698d..7104a2f1 100644
--- a/scan.go
+++ b/scan.go
@@ -6,8 +6,8 @@ package xorm
 
 import (
 	"database/sql"
-	"fmt"
 
+	"xorm.io/xorm/convert"
 	"xorm.io/xorm/core"
 	"xorm.io/xorm/dialects"
 )
@@ -86,30 +86,11 @@ func (engine *Engine) row2mapInterface(rows *core.Rows, types []*sql.ColumnType,
 	}
 
 	for ii, key := range fields {
-		switch t := scanResultContainers[ii].(type) {
-		case *sql.NullInt32:
-			resultsMap[key] = t.Int32
-		case *sql.NullInt64:
-			resultsMap[key] = t.Int64
-		case *sql.NullFloat64:
-			resultsMap[key] = t.Float64
-		case *sql.NullString:
-			resultsMap[key] = t.String
-		case *sql.NullTime:
-			if t.Valid {
-				resultsMap[key] = t.Time.In(engine.TZLocation).Format("2006-01-02 15:04:05")
-			} else {
-				resultsMap[key] = nil
-			}
-		case *sql.RawBytes:
-			if t == nil {
-				resultsMap[key] = nil
-			} else {
-				resultsMap[key] = []byte(*t)
-			}
-		default:
-			return nil, fmt.Errorf("unknow type: %v", t)
+		res, err := convert.Interface2Interface(engine.TZLocation, scanResultContainers[ii])
+		if err != nil {
+			return nil, err
 		}
+		resultsMap[key] = res
 	}
 	return resultsMap, nil
 }