How to Find Users with the Latest Values for Each ID in Oracle?

Find the latest value of each ID in Oracle database

In Oracle database, you can use outer joins to extract specific rows from a table. To find the row with the maximum value of a specific column for each distinct value in another column, follow these steps:

<code class="language-sql">SELECT t1.*
FROM mytable t1
LEFT OUTER JOIN mytable t2 ON (t1.UserId = t2.UserId AND t1.Date < t2.Date)
WHERE t2.UserId IS NULL;</code>

Instructions:

1. Outer join connects t1 with t2 based on the condition that the UserId matches and the date in t1 is less than the date in t2.
2. For each pair of matching rows, the query selects all columns in t1.
3. The WHERE clause filters out rows in t2 that have matching rows with larger dates. This ensures that only the row with the highest date for each UserId is returned.

Note:

This query only considers the Date column and ignores other columns in the table. To adjust the query for additional filtering, modify the join conditions accordingly.

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