We can remove the duplicate rows from a statement’s result set using a PostgreSQL DISTINCT clause in the SELECT statement. The PostgreSQL DISTINCT clause keeps only one row for all groups of duplicate rows. PostgreSQL DISTINCT removes all duplicate rows and maintains only one row for a group o...
In PostgreSQL, you can use the DISTINCT clause to retrieve unique rows based on one or more columns. By specifying multiple columns with DISTINCT, you filter the results to return only the unique combinations of the specified columns. Additionally, PostgreSQL provides a DISTINCT ON clause that all...
Use the PostgreSQLunnest ()Function WithDISTINCTClause TheDISTINCTclause is used in multiple database languages to remove duplicates. In PostgreSQL, it can remove all the duplicates of any kind of data, whether an integer, string, etc., but it has a limitation in that it can only remove dupl...
1. DISTINCT is a reserved keyword in PostgreSQL, so we cannot specify it as an object name. postgres=#createtabledistinct(nint);ERROR: syntax error at or near "distinct" 2. In a SELECT query we cannot have more than one DISTINCT keyword: postgres=#selectdistinct1,distinct2;ERROR: syntax ...
“conditions” names the conditions that must be met in order to select the records If you don’t want to remove duplicate data, or if you’re sure that there will be no duplicates in the result set, then you can use ALL instead of DISTINCT. But ALL is the default keyword in SQL st...
Sometimes, you may want to use array_agg in combination with a subquery to aggregate data more flexibly. Code: SELECT array_agg(name) AS all_students FROM (SELECT DISTINCT name FROM students) AS unique_names; -- Get unique names before aggregation ...
This way you can find and delete the duplicate rows from a table in PostgreSQL. Conclusion PostgreSQL offers multiple ways to find and delete duplicate rows. For finding the duplicates, we can utilize the Postgres COUNT() function. While to remove duplicate rows, we can use the “DELETE USIN...
The syntax for the SQL AVG function for MySQL, PostgreSQL, and SQL Server is: AVG([ALL|DISTINCT]expression1, expression2, expression3 ….) The syntax for DB2 & Oracle is: AVG([ALL|DISTINCT] expression1, expression2, expression3..) OVER (windows_clause) ...
Let's try the same example that we mentioned in the chapter Why use SQL in pandas: extracting the unique species of penguins who are males and who have flippers longer than 210 mm: print(sqldf('''SELECT DISTINCT species FROM penguins WHERE sex = 'Male' AND flipper_length_mm > 210'''...
Aggregates having ORDER BY or DISTINCT can use pre-sorted data Previously, we always needed to sort tuples before doing aggregation. With PostgreSQL 16, an index can provide pre-sorted input, which will be directly used for aggregation EXPLAIN (COSTS OFF) SELECT SUM(c1 ORDER BY c1), MAX...