I agree.  Yes, MS might have good reasons for dropping the cache in those cases, but it should document that it will do that.

That seems to be normal SQL Server activity, to clear the plan cache when certain ALTER DATABASE statements are executed.  Ref:

https://www.sqlskills.com/blogs/erin/query-store-and-the-plan-cache-flushing/

Your table looks to be clustered first (probably only) on ID.  Add add_date after ID in the clus index to help that type of query.

Oops, I misread, I thought the 3rd column was just INCLUDEd, and that it had the same key columns as the original index.

The new index should handle any existing fk constraint(s), since both indexes have the same keys.

A unique constraint should be a different structure, i.e., you'd have to use a DROP...

Yes, you can delete idx1.  If you use hints that force use of that specific index (which is very rare (or at least should be!)), then you would have to...

SELECT  T1.UNDERLYING_SYMBOL,        
        T1.QUOTE_DATE,    
    ...

OK.  Let's both write a report with control breaks.  I'll do it in COBOL ... in an hour or so.  (Good COBOL programmers had templates for each major...

Sure COBOL had about a 12 year head start on C (1959ish versus 1972ish) but I would find it hard to be convinced that anything written in the 1973...

For a specific day, then:

Select
Name
,Login_Email_Address
,CAST(Date AS date) AS Date
from User_acticvity
Group By Name, Login_Email_Address, CAST(Date AS date) AS Date
Having Sum(Case When action = 'Login' Then 1 Else 0...

I suggest you consider "ingredients" as an entity rather than separate "items" and "fluids". ingredient would be a super-type, with sub-types of either item or fluid, while allowing for other...

Since you didn't put aliases on the column names, I (we) have NO idea which table each column comes from; therefore, I had to use xx. as a dummy/generic alias.

I...

Cool, I can help more/fully with SQL Server:

SET ANSI_NULLS ON;
SET QUOTED_IDENTIFIER ON;
GO
CREATE TRIGGER dbo.trigger_name
ON dbo.table_name
AFTER INSERT
AS
UPDATE tn
SET col1=GETDATE(), col2=0, col3='' /*, ...*/
FROM dbo.table_name tn
INNER JOIN inserted i...

Which dbms are you using?  SQL Server? Access? Oracle?

This is a SQL Server forum.  Someone here might be able to help you with another dbms, but less so than with...

That's very odd.  Could you provide the CREATE INDEX command you are using (naturally change names as needed to protect your actual object/column names).