diff --git a/dialects/oracle/oracle.go b/dialects/oracle/oracle.go
index 9483ebc4..6bbef519 100644
--- a/dialects/oracle/oracle.go
+++ b/dialects/oracle/oracle.go
@@ -10,19 +10,33 @@ import (
 
 	_ "github.com/godror/godror"
 	"github.com/jinzhu/gorm"
+	_ "github.com/mattn/go-oci8"
+	_ "gopkg.in/rana/ora.v4"
 )
 
+//const dialectName = "godror"
+// const dialectName = "ora"
+const dialectName = "oci8"
+
 type oracle struct {
 	db gorm.SQLCommon
 	gorm.DefaultForeignKeyNamer
 }
 
 func init() {
-	gorm.RegisterDialect("godror", &oracle{})
+	gorm.RegisterDialect(dialectName, &oracle{})
+
+}
+
+func (s *oracle) fieldCanAutoIncrement(field *gorm.StructField) bool {
+	if value, ok := field.TagSettingsGet("AUTO_INCREMENT"); ok {
+		return strings.ToLower(value) != "false"
+	}
+	return field.IsPrimaryKey
 }
 
 func (oracle) GetName() string {
-	return "goracle"
+	return dialectName
 }
 
 func (oracle) BindVar(i int) string {
@@ -30,12 +44,13 @@ func (oracle) BindVar(i int) string {
 }
 
 func (oracle) Quote(key string) string {
-	return fmt.Sprintf("%s", key)
+	return key
 }
 
-func (s oracle) CurrentDatabase() (name string) {
+func (s oracle) CurrentDatabase() string {
+	var name string
 	s.db.QueryRow("SELECT ORA_DATABASE_NAME as \"Current Database\" FROM DUAL").Scan(&name)
-	return
+	return name
 }
 
 func (oracle) DefaultValueStr() string {
@@ -44,40 +59,53 @@ func (oracle) DefaultValueStr() string {
 
 func (s oracle) HasColumn(tableName string, columnName string) bool {
 	var count int
-	currentDatabase, tableName := currentDatabaseAndTable(&s, tableName)
-	fmt.Printf(currentDatabase)
-	s.db.QueryRow("SELECT count(*) FROM ALL_TAB_COLUMNS WHERE TABLE_NAME = ? AND COLUMN_NAME = ?", tableName, columnName).Scan(&count)
-	return count > 0
+	_, tableName = currentDatabaseAndTable(&s, tableName)
+	tableName = strings.ToUpper(tableName)
+	columnName = strings.ToUpper(columnName)
+	if err := s.db.QueryRow("SELECT count(*) FROM ALL_TAB_COLUMNS WHERE TABLE_NAME = :1 AND COLUMN_NAME = :2", tableName, columnName).Scan(&count); err == nil {
+		return count > 0
+	} else {
+		fmt.Println(err)
+	}
+	return false
 }
 
 func (s oracle) HasForeignKey(tableName string, foreignKeyName string) bool {
 	var count int
-	currentDatabase, tableName := currentDatabaseAndTable(&s, tableName)
-	fmt.Printf(currentDatabase)
-	s.db.QueryRow(`SELECT count(*)
+	_, tableName = currentDatabaseAndTable(&s, tableName)
+	tableName = strings.ToUpper(tableName)
+	if err := s.db.QueryRow(`SELECT count(*)
   FROM all_cons_columns a
   JOIN all_constraints c ON a.owner = c.owner
                         AND a.constraint_name = c.constraint_name
-                        AND a.constraint_name = ?
+                        AND a.constraint_name = :1
   JOIN all_constraints c_pk ON c.r_owner = c_pk.owner
                            AND c.r_constraint_name = c_pk.constraint_name
  WHERE c.constraint_type = 'R'
-   AND a.table_name = ?;`, foreignKeyName, tableName).Scan(&count)
-	return count > 0
+   AND a.table_name = :2 ;`, foreignKeyName, tableName).Scan(&count); err == nil {
+	   return count > 0
+   }
+	return false
 }
 
 func (s oracle) HasIndex(tableName string, indexName string) bool {
 	var count int
-	s.db.QueryRow("SELECT count(*) FROM ALL_INDEXES WHERE INDEX_NAME = ? AND TABLE_NAME = ?", indexName, tableName).Scan(&count)
-	return count > 0
+	tableName = strings.ToUpper(tableName)
+	indexName = strings.ToUpper(indexName)
+	if err := s.db.QueryRow("SELECT count(*) FROM ALL_INDEXES WHERE INDEX_NAME = :1 AND TABLE_NAME = :2", indexName, tableName).Scan(&count); err == nil {
+		return count > 0
+	}
+	return false
 }
 
 func (s oracle) HasTable(tableName string) bool {
 	var count int
-	currentDatabase, tableName := currentDatabaseAndTable(&s, tableName)
-	fmt.Printf(currentDatabase)
-	s.db.QueryRow("SELECT DISTINCT OBJECT_NAME FROM USER_OBJECTS WHERE OBJECT_TYPE = 'TABLE' AND OBJECT_NAME = ?", tableName).Scan(&count)
-	return count > 0
+	_, tableName = currentDatabaseAndTable(&s, tableName)
+	tableName = strings.ToUpper(tableName)
+	if err := s.db.QueryRow("select count(*) from user_tables where table_name = :1", tableName).Scan(&count); err == nil {
+		return count > 0
+	} 
+	return false
 }
 
 func (oracle) LastInsertIDReturningSuffix(tableName, columnName string) string {
@@ -99,7 +127,7 @@ func (s oracle) RemoveIndex(tableName string, indexName string) error {
 }
 
 func (oracle) SelectFromDummyTable() string {
-	return "SELECT * FROM DUAL"
+	return "FROM DUAL"
 }
 
 func (s *oracle) SetDB(db gorm.SQLCommon) {
@@ -122,17 +150,24 @@ func (s *oracle) DataTypeOf(field *gorm.StructField) string {
 		case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint, reflect.Uint8,
 			reflect.Uint16, reflect.Uintptr, reflect.Int64, reflect.Uint32, reflect.Uint64,
 			reflect.Float32, reflect.Float64:
-			sqlType = "NUMBER"
+			if s.fieldCanAutoIncrement(field) {
+				sqlType = "NUMBER GENERATED BY DEFAULT AS IDENTITY"
+			} else {
+				sqlType = "NUMBER"
+			}
 		case reflect.String:
 			if _, ok := field.TagSettingsGet("SIZE"); !ok {
 				size = 0 // if SIZE haven't been set, use `text` as the default type, as there are no performance different
 			}
-
-			if size > 0 && size < 4000 {
+			switch {
+			case size > 0 && size < 4000:
 				sqlType = fmt.Sprintf("VARCHAR2(%d)", size)
-			} else {
+			case size == 0:
+				sqlType = "VARCHAR2 (4000)"
+			default:
 				sqlType = "CLOB"
 			}
+
 		case reflect.Struct:
 			if _, ok := dataValue.Interface().(time.Time); ok {
 				sqlType = "TIMESTAMP WITH TIME ZONE"
@@ -143,15 +178,7 @@ func (s *oracle) DataTypeOf(field *gorm.StructField) string {
 			}
 		default:
 			if gorm.IsByteArrayOrSlice(dataValue) {
-				sqlType = "VARCHAR2"
-
-				/*if isUUID(dataValue) {
-					sqlType = "VARCHAR2"
-				}
-
-				if isJSON(dataValue) {
-					sqlType = "CLOB"
-				}*/
+				sqlType = "VARCHAR2 (4000)"
 			}
 		}
 	}
@@ -163,6 +190,22 @@ func (s *oracle) DataTypeOf(field *gorm.StructField) string {
 	if strings.TrimSpace(additionalType) == "" {
 		return sqlType
 	}
+	if strings.EqualFold(sqlType, "json") {
+		sqlType = "VARCHAR2 (4000)"
+	}
+
+	// For oracle, we have to redo the order of the Default type from tag setting
+	notNull, _ := field.TagSettingsGet("NOT NULL")
+	unique, _ := field.TagSettingsGet("UNIQUE")
+	additionalType = notNull + " " + unique
+	if value, ok := field.TagSettingsGet("DEFAULT"); ok {
+		additionalType = fmt.Sprintf("%s %s %s", "DEFAULT", value, additionalType)
+		// additionalType = additionalType + " DEFAULT " + value
+	}
+
+	if value, ok := field.TagSettingsGet("COMMENT"); ok {
+		additionalType = additionalType + " COMMENT " + value
+	}
 	return fmt.Sprintf("%v %v", sqlType, additionalType)
 }
 func (s oracle) LimitAndOffsetSQL(limit, offset interface{}) (sql string, err error) {