It's a bit long-winded, but this is what I came up with

DECLARE @TestData table (id int, dateVal varchar(12));

INSERT INTO @TestData ( id, dateVal )
VALUES ( 1, '00:02:03:123'...

You need to first cast the string to a format that is recognisable to SQL

Something like this

DECLARE @SourceTable table (ANNOUNCE_DATETIME varchar(50));

INSERT INTO @SourceTable (ANNOUNCE_DATETIME)
VALUES ( '"20180919T201400+0000"' )
...

Try something along these lines ...

WITH cteDiff (
  SELECT  A, C, D, E
  FROM    [Database].dbo.[Table]
  WHERE   B ...

Try something like this

if object_id('tempdb..#temp') is not null
  drop table #temp;
GO
create table #temp
(
    date datetime,
    category varchar(3),
   ...

Be careful with global temp tables.

Multiple SPIDs could end up tripping over each other, as they can all see the global temp table.

Try something like this ...

DECLARE @RowToDelete int,@Result int;
SET @RowToDelete=1;

DELETE from table where Id=@RowToDelete;

SELECT @Result = @@ROWCOUNT;

IF @Result=1     --- Or whatever rusults is
 ...

Something like this ...

WITH cteWindows AS (
  SELECT c.MonthStart
       , windowStart = DATEADD(mm, -2, c.MonthStart)
     ...

Something like this ...

DECLARE @StartOfCurrentWindow date = '2024-10-01';
DECLARE @StartOfNextWindow    date = DATEADD(MONTH, 3, @StartOfCurrentWindow);

WITH cteBase AS (
  SELECT c.MonthStart
    ...

She did have a shedload of LIKEs.  The "upgrade" on the site years ago hasn't helped much...

Congratulations @jeff-moden

Finally overtook the high priestess on the SSC overall leaderboard.

Come on @Jeff-Moden.  One more post ....

SELECT DISTINCT tp.client_id AS Member_ID
     , tp.PaidDate AS Paid_Date
     , tp.DOS
FROM #ins_temp tp
WHERE (@dateChoice = 'Paid_Date' and tp.PaidDate...

You could use dynamic SQL

DECLARE @SQL nvarchar(MAX);

SELECT @SQL = N'
SELECT  DISTINCT
        Member_ID = tp.client_id
     ...

This is a similar query that might perform differently.  You need to test

SELECT  i.ItemID
      , i.ItemName
     ...

It is difficult to design any queries without knowing anything about your tables and their indexes.

That said, this might help.

SELECT i.ItemID
     , i.ItemName
...