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)
}

			}
		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 {

				if !field.PrimaryKey &&
					(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
			}
		}
	}

// by the driver ok is false.
func (ci *ColumnType) Length() (length int64, ok bool) {
	return ci.length, ci.hasLength
}

// DecimalSize returns the scale and precision of a decimal type.
// If not applicable or if not supported ok is false.
func (ci *ColumnType) DecimalSize() (precision, scale int64, ok bool) {
	return ci.precision, ci.scale, ci.hasPrecisionScale
}

		{"TBSCertificateList.ThisUpdate", Field, 0},
		{"TBSCertificateList.Version", Field, 0},
	},
	"database/sql": {
		{"(*ColumnType).DatabaseTypeName", Method, 8},
		{"(*ColumnType).DecimalSize", Method, 8},
		{"(*ColumnType).Length", Method, 8},
		{"(*ColumnType).Name", Method, 8},
		{"(*ColumnType).Nullable", Method, 8},
		{"(*ColumnType).ScanType", Method, 8},
		{"(*Conn).BeginTx", Method, 9},