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Problem · Database

Null Counts by Column

● Easy

World Wide TechnologyINTERNPHONE SCREEN

Problem statement

You are given a Pandas dataframe named records with columns record_id, name, email, and score.

Return a dataframe containing the number of null values in each input column. The result must have columns column_name and null_count, include every input column even when its count is zero, and follow the input schema order shown above.

Table schema

Pandas

Use the same input data with any supported language. Open the Schema tab in the editor to see the generated SQL setup or Pandas DataFrames.

records

Column	Type	Nullable	Description
record_id	Integer	Yes	—
name	Text	Yes	—
email	Text	Yes	—
score	Decimal	Yes	—

Expected result

Your query or function must return these columns.

Column	Type	Nullable	Description
column_name	Text	No	—
null_count	Integer	No	—

Row order: must match exactly. Numeric tolerance: 0.

Constraints

records contains at most 10^5 rows.
All four input columns are nullable.
A null is any value recognized as missing by Pandas isna().