(len(matches2) == 1 && matches2[0][1] != fmt.Sprint(length) && ok) {
					alterColumn = true
				}
			}
		}

		// check precision
		if precision, _, ok := columnType.DecimalSize(); ok && int64(field.Precision) != precision {
			if regexp.MustCompile(fmt.Sprintf("[^0-9]%d[^0-9]", field.Precision)).MatchString(m.DataTypeOf(field)) {
				alterColumn = true
			}
		}
	}

	// check nullable

			tests.AssertObjEqual(t, parsedField, f, "Name", "DBName", "BindNames", "DataType", "PrimaryKey", "AutoIncrement", "Creatable", "Updatable", "Readable", "HasDefaultValue", "DefaultValue", "NotNull", "Unique", "Comment", "Size", "Precision", "TagSettings")

			if f.DBName != "" {
				if field, ok := s.FieldsByDBName[f.DBName]; !ok || parsedField != field {
					t.Errorf("schema %v failed to look up field with dbname %v", s, f.DBName)
				}
			}

			}
		case "salary":
			if precision, o, _ := columnType.DecimalSize(); (fullSupported || precision != 0) && precision != 2 {
				t.Fatalf("salary's precision should be 2, but got %v %v", precision, o)
			}
		case "birthday":
			if precision, _, _ := columnType.DecimalSize(); (fullSupported || precision != 0) && precision != 2 {
				t.Fatalf("birthday's precision should be 2, but got %v", precision)
			}
		}
	}

	if ct.LengthValue.Valid {
		return ct.LengthValue.Int64, true
	}
	return ct.SQLColumnType.Length()
}

// DecimalSize returns the scale and precision of a decimal type.
func (ct ColumnType) DecimalSize() (precision int64, scale int64, ok bool) {
	if ct.DecimalSizeValue.Valid {
		return ct.DecimalSizeValue.Int64, ct.ScaleValue.Int64, true
	}
	return ct.SQLColumnType.DecimalSize()
}

	ColumnType() (columnType string, ok bool) // varchar(64)
	PrimaryKey() (isPrimaryKey bool, ok bool)
	AutoIncrement() (isAutoIncrement bool, ok bool)
	Length() (length int64, ok bool)
	DecimalSize() (precision int64, scale int64, ok bool)
	Nullable() (nullable bool, ok bool)
	Unique() (unique bool, ok bool)
	ScanType() reflect.Type
	Comment() (value string, ok bool)
	DefaultValue() (value string, ok bool)
}

	}

	if num, ok := field.TagSettings["SIZE"]; ok {
		if field.Size, err = strconv.Atoi(num); err != nil {
			field.Size = -1
		}
	}

	if p, ok := field.TagSettings["PRECISION"]; ok {
		field.Precision, _ = strconv.Atoi(p)
	}

	if s, ok := field.TagSettings["SCALE"]; ok {
		field.Scale, _ = strconv.Atoi(s)
	}

	// default value is function or null or blank (primary keys)