code: func (e *UpdateExec) setMessage() {
  	stmtCtx := e.ctx.GetSessionVars().StmtCtx
  	numMatched := e.matched
  	numChanged := stmtCtx.UpdatedRows()
  	numWarnings := stmtCtx.WarningCount()
  	msg := fmt.Sprintf(mysql.MySQLErrName[mysql.ErrUpdateInfo], numMatched, numChanged, numWarnings)
  	stmtCtx.SetMessage(msg)
  }
docs: // setMessage sets info message(ERR_UPDATE_INFO) generated by UPDATE statement