code: func (ec ErrClass) String() string {
  	switch ec {
  	case ClassAutoid:
  		return "autoid"
  	case ClassDDL:
  		return "ddl"
  	case ClassDomain:
  		return "domain"
  	case ClassExecutor:
  		return "executor"
  	case ClassExpression:
  		return "expression"
  	case ClassInspectkv:
  		return "inspectkv"
  	case ClassMeta:
  		return "meta"
  	case ClassKV:
  		return "kv"
  	case ClassOptimizer:
  		return "optimizer"
  	case ClassParser:
  		return "parser"
  	case ClassPerfSchema:
  		return "perfschema"
  	case ClassPrivilege:
  		return "privilege"
  	case ClassSchema:
  		return "schema"
  	case ClassServer:
  		return "server"
  	case ClassStructure:
  		return "structure"
  	case ClassVariable:
  		return "variable"
  	case ClassTable:
  		return "table"
  	case ClassTypes:
  		return "types"
  	}
  	return strconv.Itoa(int(ec))
  }
docs: // String implements fmt.Stringer interface.