code: func ConvertCharsetCollateToLowerCaseIfNeed(tbInfo *model.TableInfo) {
  	if tbInfo.Version >= model.TableInfoVersion3 {
  		return
  	}
  	tbInfo.Charset = strings.ToLower(tbInfo.Charset)
  	tbInfo.Collate = strings.ToLower(tbInfo.Collate)
  	for _, col := range tbInfo.Columns {
  		col.Charset = strings.ToLower(col.Charset)
  		col.Collate = strings.ToLower(col.Collate)
  	}
  }
docs: // ConvertCharsetCollateToLowerCaseIfNeed convert the charset / collation of table and its columns to lower case,
  // if the table's version is prior to TableInfoVersion3.