Can you filter SQL data before importing to Excel?

fredtrev 

In general query folding shall work for such transformation as well. In Power Query steps are

- filter column A

- filter column B

- add custom column with =[A] = "a" and [B] = 1

- filter custom column keeping FALSE

- remove custom column

Generated script will be like

let
    Source = database,
    getData = Source{[Schema="dbo",Item="Table"]}[Data],

    #"Filtered Rows" = Table.SelectRows(
        getData,
        each
            ([A] = "a" or [A] = "b" or [A] = "c") and
            ([B] = 1 or [B] = 2 or [B] = 3 )),
    #"Added Custom" = Table.AddColumn(
        #"Filtered Rows",
        "Custom",
        each [A] = "a" and [B] = 1),
    #"Filtered Rows1" = Table.SelectRows(
        #"Added Custom",
        each ([Custom] = false)),
    #"Removed Columns" = Table.RemoveColumns(
        #"Filtered Rows1",
        {"Custom"})
in
    #"Removed Columns"

Assuming you didn't break query folding on previous steps, If right click on last step in above and View Native Query, generated SQL script will be like

select [_].[someField],
    [_].[A],
    [_].[B],
    [_].[anotherField]
from 
(
    select [_].someField] as [someField],
        [_].[A] as [A],
        [_].[B] as [B],
        [_].[anotherField] as [anotherField],
        case
            when [_].[A] = 'a' and [_].[B] = 1
            then 1
            when not ([_].[A] = 'a' and [_].[B] = 1)
            then 0
            else null
        end as [Custom]
    from 
    (
        select [_].[someField],
            [_].[A],
            [_].[B],
            [_].[anotherField]
        from [dbo].[Table] as [_]
        where (([_].[A] = 'a' or [_].[A] = 'b') or [_].[A] = 'c') and (([_].[B] = 1 or [_].[B] = 2) or [_].[B] = 3)
    ) as [_]
) as [_]
where [_].[Custom] = 0