![]() ![]() ![]() The next step is to number the duplicate rows with the row_number window function: select row_number() over (partition by email),įrom can then wrap the above query filtering out the rows with row_number column having a value greater than 1. Returns, are the duplicate emails in the table with their counts. The following query picks the email column to deduplicate, select email, You'll have to remove duplicate rows in the table before a unique index can be added.Ī great way to find duplicate rows is by using window functions – supported by most major databases.Ĭonsider a follow table dedup with duplicates: duplicate values in one column However, at times, your data might come from external dirty data sources and your table will have duplicate rows. Using AWS Athena to understand your AWS billsĬanada Province & Census Division ShapefilesĪ common mechanism for defending against duplicate rows in a database table is to put a unique index on the column. Modeling: Denormalized Dimension Tables with Materialized Views for Business Users Gap analysis to find missing values in a sequenceĮstimating Demand Curves and Profit-Maximizing Pricing Querying JSON (JSONB) data types in PostgreSQL Using SQL to analyze Bitcoin, Ethereum & Cryptocurrency Performance Multichannel Marketing Attribution ModelingĪnalyzing Net Promoter Score (NPS) surveys in SQL to improve customer satisfaction & loyalty SQL's NULL values: comparing, sorting, converting and joining with real values SQL Server: Date truncation for custom time periods like year, quarter, month, etc.įilling Missing Data & Plugging Gaps by Generating a Continuous Seriesįinding Patterns & Matching Substrings using Regular ExpressionsĬoncatenating Rows of String Values for Aggregation Redshift: Generate a sequential range of numbers for time series analysis MySQL: Generate a sequential range of numbers for time series analysis ![]() Understanding how Joins work – examples with Javascript implementation First steps with Silota dashboarding and chartingĬalculating Exponential Moving Average with Recursive CTEsĬalculating Difference from Beginning RowĬreating Pareto Charts to visualize the 80/20 principleĬalculating Summaries with Histogram Frequency DistributionsĬalculating Relationships with Correlation MatricesĪnalyzing Recency, Frequency and Monetary value to index your best customersĪnalyze Mailchimp Data by Segmenting and Lead scoring your email listĬalculating Top N items and Aggregating (sum) the remainder into "All other"Ĭalculating Linear Regression Coefficientsįorecasting in presence of Seasonal effects using the Ratio to Moving Average method ![]()
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