Problem 2 of 11 · Data quality & validationNext: Profile how complete each column is

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Practice / SQL / Data quality & validation

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EasyAbout 4 minData quality & validation

How much duplication is in the feed?

Quantify the duplication in dupes: return total_rows and unique_customers (distinct customer_id) in one row.

Columns

dupes4 columns

columntype

customer_idVARCHAR

emailVARCHAR

phoneVARCHAR

loaded_tsTIMESTAMP WITH TIME ZONE

The table

9 rows · 4 columns

dupesfirst 5 of 9 rows

customer_idemailphoneloaded_ts

c_001alice@old.com+1-111-11112026-05-01 10:00:00

c_001alice@new.comNULL2026-05-15 10:00:00

c_001NULL+1-111-22222026-05-20 10:00:00

c_002bob@example.com+1-222-22222026-06-01 09:00:00

c_003carol@example.com+1-333-33332026-04-01 08:00:00

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