擅长:python、mysql、java
<p>你要找的是<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.map.html" rel="nofollow noreferrer">^{<cd1>}</a>:</p>
<pre><code>df["download_date"] = df["mobile_no"].map(df2.set_index("mobile_no")["download_date"])
print (df)
name mobile_no download_date
0 Hector ABC 123.0 2021-05-30
1 Hector ABC 287.0 2020-09-28
2 Jose JKD 567.0 NaN
3 Luis AH NaN NaN
4 Billy DH NaN NaN
5 Harry AC 569.0 2020-01-15
</code></pre>