Power Query - M (Table. Select)

Power Query
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In your video on Creating Records For Daily Values With Power Query [Creating Records For Daily Values With Power Query | Enterprise DNA]

Creating Records For Daily Values With Power Query | Enterprise DNA

Require clarification in the following M Code

Table.SelectRows(BufferedTable, (BT)=> BT[ID]= _[ID]and BT[Date]>= _[Date] ))

Table.SelectRows requires only two parameters table and condition as function. The above code compares the current record with the Buffered table .

My question is how does the buffered table gets **automatically assigned to the variable BT in the function (BT) =>, before comparing with current record held by _(underscore)

The function starts comparing the selected columns of the buffered with the current record

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@Sairam

Table.SelectRows(BufferedTable, (BT)=> BT[ID]= _[ID]and BT[Date]>= _[Date] ))

()=> is a custom function that doesn’t accept a parameter
(BT)=> is a custom function that accepts a parameter of any type, since BufferedTable is on left it is automatically passed as an argument to this function

more explicitly it passes a record, row by row.
(BT as record ) => is a custom function that accepts a value of type record.

()=> equals each

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Thanks @AntrikshSharma
(_)=> invokes Current record ; variable name can also be used in lieu of _underscore .

Hence I was amazed as to how automatic assignment of BufferedTable to the left,is passed as an argument to the function (BT)=>

M is the new paradigm of using codes to extinguish codes. @Melissa is the God of M code.

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Bumping this post for more visibility.

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