New to BI. Writing SQL queries to parse data. I am obviously missing something.

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sdjensen wrote:

When I select from a SQL source in PBI Desktop I always make my queries in the Query Editor like this. I prefer using the advanced editor to write the M# code myself, and use parameters to have my values for Server and Database. I do this for 2 reasons - I can easily create a new query by dublicating one of my other queries and then just replace the T-SQL code and I just have to change 2 values if my data source changes since I just change the parameters and then don't have to change all my queries.

 

let
    Source = Sql.Database(Server, Database, [Query="
--SQL Query Start
SELECT
	a.DWID_Customer AS 'CustomerKey'
	, a.CustomerNo AS 'Customer No'
	, a.Name AS 'Customer Name'
	, a.CustomerLabel AS 'Customer'
	, a.CustomerPostingGroup AS 'Customer Posting Group'
	, a.Country AS 'Customer Country'
	, a.City + ', ' + a.Country AS 'Customer City'
	, a.SalespersonCode AS 'Salesperson Code'
	, a.SalespersonName AS 'Salesperson Name'
	, a.SalespersonName + ' - ' + a.SalespersonCode AS 'Salesperson'
FROM D_Customer a
--SQL Query End
    "])
in
    Source

 

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Could someone please spell this out easier for me? I am not a SQL guy but really need to go this route with my complex BI model. I have many tables loading (some with millions of rows that I would like to try and filter before they load into query editor first) and many editor steps that I feel could be reduced by SQL coding doing a lot of the joins and filters I need done.

My model times out and fails scheduled refresh during business hours a lot due to everything taxing on the SQL server.

Is there a good beginniners book to SQL I could pick up to maybe learn enough to join and filter as I need too?