Left join returning total records in SQL instead of matching records

Question

I've written a Left join between two tables. My table structure is

SELECT  D.DLNOPK, D.STARTDT

FROM    DEALDETAILS D

LEFT JOIN 

            DEALCUSTOMERDETAILS P

ON      P.DLNO = D.DLNOPK

    WHERE P.CUSTOMERID = 'ABCD';

Actually the total number of rows in Deal details is 100, but even after writing the where clause, it returns 100 rows.

My table structure is

DEALDETAILS

DLNOPK | STARTDT

DEALCUSTOMERDETAILS

DLNO | CUSTOMERID

What is wrong with the where clause?

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Answer 1

Here the total query you ask ^^

SELECT  D.DLNOPK, D.STARTDT
FROM    DEALDETAILS D
LEFT JOIN   DEALCUSTOMERDETAILS P
ON    D.DLNOPK =  P.DLNO
WHERE P.CUSTOMERID = 'ABCD';

Left join returning total records in SQL instead of matching records

DEALDETAILS

DEALCUSTOMERDETAILS

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