Had a few minutes to kill... Here's a solution using what is commonly referred to as the "Quirky Update". I included the code to make sample data...

USE tempdb

GO

IF OBJECT_ID('tempdb.dbo.dimdate') IS NOT NULL DROP TABLE dbo.DimDate;

IF OBJECT_ID('tempdb.dbo.totalsdata') IS NOT NULL DROP TABLE dbo.totalsdata;

create table dimdate (datevalue date);

create table totalsdata (datevalue date, totalvalue int);

GO

DECLARE @startdate date=getdate();

-- populate dimDate

WITH iTally(n) AS

(SELECT TOP(13) ROW_NUMBER() OVER (ORDER BY (SELECT NULL))-1

FROM sys.all_columns)

INSERT dbo.DimDate

SELECT dateadd(day,n,@startdate) AS datevalue

FROM iTally;

-- populate dimDate

WITH TotalsData_prep AS

(SELECT datevalue, totalvalue

FROM (VALUES (3,55),(7,66),(9,77),(11,88)) t(datevalue,totalvalue))

INSERT dbo.TotalsData

SELECTdateadd(day,datevalue,@startdate) AS datevalue,

totalvalue

FROM TotalsData_prep;

GO

-- using the "Quirky Update"

DECLARE @x TABLE(datevalue date, tv int);

DECLARE @TV int=0;

INSERT @x

SELECT d.datevalue, coalesce(t.totalvalue,0)

FROM dimdate d

LEFT JOIN dbo.TotalsData t

ON d.datevalue=t.datevalue;

UPDATE @x

SET @TV=tv= CASE WHEN tv<>0 THEN tv ELSE @TV END

FROM dbo.TotalsData

SELECT *

FROM @x;