diff --git a/dialects/mssql.go b/dialects/mssql.go
index 7617c4ad..8e76e538 100644
--- a/dialects/mssql.go
+++ b/dialects/mssql.go
@@ -242,7 +242,7 @@ func (db *mssql) SetParams(params map[string]string) {
 		var t = strings.ToUpper(defaultChar)
 		switch t {
 		case "NCHAR", "CHAR":
-			db.defaultChar = defaultChar
+			db.defaultChar = t
 		default:
 			db.defaultChar = "CHAR"
 		}
@@ -297,10 +297,26 @@ func (db *mssql) SQLType(c *schemas.Column) string {
 	case schemas.BigInt:
 		res = schemas.BigInt
 		c.Length = 0
+	case schemas.NVarchar:
+		res = t
+		if c.Length == -1 {
+			res += "(MAX)"
+		}
 	case schemas.Varchar:
 		res = db.defaultVarchar
+		if c.Length == -1 {
+			res += "(MAX)"
+		}
 	case schemas.Char:
 		res = db.defaultChar
+		if c.Length == -1 {
+			res += "(MAX)"
+		}
+	case schemas.NChar:
+		res = t
+		if c.Length == -1 {
+			res += "(MAX)"
+		}
 	default:
 		res = t
 	}
@@ -424,13 +440,17 @@ func (db *mssql) GetColumns(queryer core.Queryer, ctx context.Context, tableName
 			col.SQLType = schemas.SQLType{Name: schemas.TimeStampz, DefaultLength: 0, DefaultLength2: 0}
 		case "NVARCHAR":
 			col.SQLType = schemas.SQLType{Name: schemas.NVarchar, DefaultLength: 0, DefaultLength2: 0}
-			col.Length /= 2
-			col.Length2 /= 2
+			if col.Length > 0 {
+				col.Length /= 2
+				col.Length2 /= 2
+			}
 		case "IMAGE":
 			col.SQLType = schemas.SQLType{Name: schemas.VarBinary, DefaultLength: 0, DefaultLength2: 0}
 		case "NCHAR":
-			col.Length /= 2
-			col.Length2 /= 2
+			if col.Length > 0 {
+				col.Length /= 2
+				col.Length2 /= 2
+			}
 			fallthrough
 		default:
 			if _, ok := schemas.SqlTypes[ct]; ok {
diff --git a/integrations/session_schema_test.go b/integrations/session_schema_test.go
index 0f839c02..bcaf30aa 100644
--- a/integrations/session_schema_test.go
+++ b/integrations/session_schema_test.go
@@ -157,7 +157,7 @@ func TestSyncTable3(t *testing.T) {
 		Id   int64
 		Name string
 		Text string `xorm:"TEXT"`
-		Char byte   `xorm:"CHAR"`
+		Char byte   `xorm:"CHAR(1)"`
 	}
 
 	assert.NoError(t, PrepareEngine())
@@ -197,9 +197,9 @@ func TestSyncTable3(t *testing.T) {
 		assert.NoError(t, err)
 		tableInfo, err := testEngine.TableInfo(new(SyncTable5))
 		assert.NoError(t, err)
-		assert.EqualValues(t, testEngine.Dialect().SQLType(tables[0].GetColumn("name")), testEngine.Dialect().SQLType(tableInfo.GetColumn("name")))
-		assert.EqualValues(t, testEngine.Dialect().SQLType(tables[0].GetColumn("text")), testEngine.Dialect().SQLType(tableInfo.GetColumn("text")))
-		assert.EqualValues(t, testEngine.Dialect().SQLType(tables[0].GetColumn("char")), testEngine.Dialect().SQLType(tableInfo.GetColumn("char")))
+		assert.EqualValues(t, testEngine.Dialect().SQLType(tableInfo.GetColumn("name")), testEngine.Dialect().SQLType(tables[0].GetColumn("name")))
+		assert.EqualValues(t, testEngine.Dialect().SQLType(tableInfo.GetColumn("text")), testEngine.Dialect().SQLType(tables[0].GetColumn("text")))
+		assert.EqualValues(t, testEngine.Dialect().SQLType(tableInfo.GetColumn("char")), testEngine.Dialect().SQLType(tables[0].GetColumn("char")))
 	}
 }