How to Get Unique Values From 2 Columns In Postgresql?

To get unique values from 2 columns in PostgreSQL, you can use the DISTINCT keyword in your SELECT query. This will return only the distinct values from the specified columns, eliminating any duplicates. Additionally, you can use the UNION or UNION ALL operator to combine the unique values from both columns into a single result set. You can also use the GROUP BY clause to group the results by the specified columns, which will also remove duplicates and return only unique combinations of values.

How to get unique values from 2 columns and find the maximum value in Postgresql?

To get unique values from two columns and find the maximum value in PostgreSQL, you can use the following SQL query:

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SELECT DISTINCT col1, col2
FROM your_table
ORDER BY col1, col2 DESC
LIMIT 1;

Replace your_table with the name of your table, col1 and col2 with the names of the columns you want to get unique values from, and DESC with ASC if you want to find the minimum value instead of the maximum.

This query will return the unique combination of values from col1 and col2 and order them by col1 and col2 in descending order. The LIMIT 1 clause ensures that only the first row (which has the maximum value) is returned.

What is the fastest approach to filter out duplicate data from 2 columns in Postgresql?

One of the fastest approaches to filter out duplicate data from 2 columns in PostgreSQL is to use the DISTINCT ON statement.

Here is an example query to filter out duplicate data from columns column1 and column2 in a table called example_table:

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SELECT DISTINCT ON (column1, column2) *
FROM example_table
ORDER BY column1, column2, id; 

This query will return only the first occurrence of each unique combination of column1 and column2 values in the table. The ORDER BY clause is used to determine the order in which rows are evaluated for duplicates.

How to find unique values from 2 columns without using DISTINCT in Postgresql?

One way to find unique values from 2 columns without using DISTINCT in Postgresql is to use a combination of GROUP BY and HAVING clauses. Here's an example query that demonstrates this approach:

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SELECT column1, column2
FROM your_table
GROUP BY column1, column2
HAVING COUNT(*) = 1;

In this query, we group the records by column1 and column2 and then use the HAVING clause to only select the groups where the count of records is equal to 1, which indicates that the combination of values in column1 and column2 is unique.