Pass parameter from Excel to SQL in PowerQuery - sql-server

Question

I want to set local variables or pass parameters from Excel to SQL. I've found similar questions, but all referred to old versions of Excel and/or the answers showed how to filter or manipulate output from a generic SQL query in the Power Query Editor, rather than pass a parameter or modify the SQL, so that the SQL Server supplies data in the needed form.
I'm building a large Microsoft Excel spreadsheet that depends on ten different SQL queries, all against a common SQL Server database. Excel and SQL Server are installed on my laptop and are current versions (as of 16 Mar 2022). All ten queries share a common date restriction, imposed in the WHERE clauses of the queries. The tables accessed and the form of output are very different, so there is no easy way to combine the ten queries into a single query. The queries contain multiple levels of aggregation (e.g. SUM(...)) so I need to restrict the records accessed prior to aggregation and passing results from the query back to Excel.
As currently written, each query begins by setting two date values in local variables. For example,
DECLARE #BEGIN_DATE AS smalldatetime;
DECLARE #END_DATE AS smalldatetime;
#BEGIN_DATE = CAST('2021-03-01 00:00' AS smalldatetime);
#END_DATE = CAST('2021-03-02 23:59' AS smalldatetime);
Every one of the ten queries includes a line in the WHERE clause similar to
WHERE
PickUpDate BETWEEN #BEGIN_DATE AND #END_DATE
Every query will use the same pair of dates. However, the column filtered (PickUpDate above) changes from one query to the next.
As it is, I have to manually edit each of the ten queries to change the two dates--twenty edits in all. This is time-consuming and error-prone. Ideally, I'd like to set the date range in the spreadsheet, in a pop-up dialog box, or any other convenient way and pass the dates to the SQL queries. Then by selecting Data > Refresh All in Excel, update all my tables at once.
Is this possible, and if so, how does one do it?

Answer 1

The answer from David Browne is generally on-target. But I found some difficulties reading data from an Excel table directly into the SQL, given security restrictions in the latest version of Excel/Power Query. Also, since this was the first time I worked directly in M-code and the advanced editor, it was challenging to fill-in the gaps.
I finally got a nice solution running; here is what worked for me.
First, I stored the parameter values in a two-column table. My table is named "ParameterTable" with column headers named "Parameter_Name" and "Value". The value(s) to pass to SQL Server are stored in the Value column. My table has two rows with row entries labeled "Begin_DateTime" and "End_DateTime".
Secondly I created a callable function named “ftnGetParameter.” Select Data > Get Data > From Other Sources > Blank Query. Then select “Advanced Editor.” Delete any boilerplate added by Excel, and enter and save this function
let theParameter=(TableName,ParameterLabel) =>
let
Source=Excel.CurrentWorkbook(){[Name=TableName]}[Content],
value = Source{[Parameter_Name=ParameterLabel]}[Value]
in
value
in
theParameter
Thirdly, code-up your SQL statement as usual. I was trying to pass dates to SQL, so I initially coded with string literals. Enter the query in the usual way. I used Data > Get Data > From Database > From SQL Server Database. Then pasted in the SQL. The two relevant lines in my query looked like this:
DECLARE #BEGIN_DATE AS SMALLDATETIME='2021-01-01 00:00';
DECLARE #END_DATE AS SMALLDATETIME='2021-12-31 23:59';
You could skip this step, but it allowed me to get complex SQL code entered, formatted, and running before I invoked the function to pass the parameters.
Finally, simply replace the string literals in the SQL with code to call the function. My first few lines of M-code looks like this:
let
Source = Sql.Database("DESKTOP-04P8E8C", "nfbdata",
[Query=
"
DECLARE #BEGIN_DATE AS SMALLDATETIME= '" & ftnGetParameter("ParameterTable","Begin_DateTime") & "';
DECLARE #END_DATE AS SMALLDATETIME='" & ftnGetParameter("ParameterTable","End_DateTime") & "' (… the query continues )
Excel will issue some warnings about running the query and prompt you to edit permissions. Once permission has been granted, the function reads the text from the parameter table and passes it into the SQL.
I found that the function call was not optional. Apparently, importing the code directly into a native call to SQL Server is considered an unacceptable security risk.
Many thanks to Mr. David Browne. His post definitely points in the right direction.

Answer 2

You can reference a table on a sheet from Power Query and integrate values from that table into your other queries. Eg if ParameterTable is a single-row table on some worksheet with a column called "StartDate", something like
let
theDate = Date.From( Record.Field(Table.First(ParameterTable),"StartDate") ),
Source = Sql.Databases("localhost"),
AdventureWorksDW2017 = Source{[Name="AdventureWorksDW2017"]}[Data],
dbo_DimDate = AdventureWorksDW2017{[Schema="dbo",Item="DimDate"]}[Data],
#"Filtered Rows" = Table.SelectRows(dbo_DimDate, each [FullDateAlternateKey] = theDate )
in
#"Filtered Rows"
for M query folding, or
let
theDate = Date.From( Record.Field(Table.First(ParameterTable),"StartDate") ),
sql = "
select *
from dimDate
where FullDateAlternateKey = '" & Text.From(theDate) & "'
",
Source = Sql.Database("localhost", "adventureworksdw2017", [Query=sql])
in
Source
for dynamic SQL.