How to count the number of times an element appears consecutively in a table in teradata?

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by denis , in category: MySQL , 22 days ago

How to count the number of times an element appears consecutively in a table in teradata?

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1 answer

Member

by lily , 21 days ago

@denis 

One way to count the number of times an element appears consecutively in a table in Teradata is by using a combination of window functions and subqueries.


Here is an example query that demonstrates how to count the number of consecutive occurrences of a specific element in a table:

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SELECT 
    element,
    COUNT(*) as consecutive_count
FROM (
    SELECT 
        element,
        ROW_NUMBER() OVER (ORDER BY some_column) as rn,
        ROW_NUMBER() OVER (PARTITION BY element ORDER BY some_column) as rn2
    FROM your_table
) subquery
GROUP BY element, rn - rn2
ORDER BY element, rn - rn2;


In this query:

  • Replace your_table with the name of your table and element with the column that contains the elements you want to count.
  • some_column is a column in your table that can be used to determine the order of the rows.
  • The subquery assigns a unique row number to each row in the table and a row number within each element partition.
  • The main query groups the rows by the difference between the two row numbers to identify consecutive occurrences of the element.
  • The final result includes the element and the count of consecutive occurrences.


You can further customize the query by adding conditions or filters to restrict the results based on your requirements.