If you want to control which member is used, add an ORDER BY clause, then the first member in this ordering is taken. on c1. If you want the first occurrence, change MAX to MIN. Recent example: When GROUP BY is present, it is not valid for the SELECT list expressions to refer to ungrouped columns except within aggregate functions, since there would be more than one possible value to return for an ungrouped column. Apr 4, 2019 · SELECT * FROM contact_methods WHERE person = '1' ORDER BY contact_type DESC LIMIT 1; Which would result in the row with id 2. I'd tried variations on SELECT DISTINCT but didn't bump into SELECT DISTINCT ON. The SELECT statement is a fundamental SQL statement used in PostgreSQL (and other relational database systems) to retrieve data from a database table. id, p. OFFSET 3. the_date DESC; Jun 20, 2016 · 1. ここ Aug 14, 2023 · By Admin August 14, 2023. Apr 1, 2022 · I have a table with 23 total rows. Incidentally, your title asks about GROUP BY, but your syntax specifies DISTINCT. May 28, 2015 · SELECT d FROM tablename ; Another would be to first UNION ALL and then use DISTINCT. And if you like you could add an ORDER BY clause to the subquery. 2. WHERE pg. Always use the ORDER BY clause to determine which entry to retain in the result set. group by tn1. そのレコードの中で、並び替える. By using the ORDER BY clause, the values in the fore_color column will be sorted in alphabetical order. If you are looking for a portable version based on the SQL standard, you can use a window function for this: Apr 22, 2023 · Postgres DISTINCT with Single Column. With DISTINCT ON in Postgres:. For the source_sql, we will use the following select statement that has four columns as output: I simplify your scenario to concentrate on the FULL OUTER JOIN part: This are the tables (think of them as the result of your first SELECT before whe UNION, and the second SELECT after said UNION ): CREATE TABLE table_a. If you want the 'biggest' uid per slug then use. level_sensor FROM station s CROSS JOIN LATERAL ( SELECT submitted_at, level_sensor FROM station_logs WHERE station_id = s. ORDER BY MAX(CreationDate) DESC, Category. It retains only one row from a set of Feb 23, 2023 · JOIN plays on plays. Here is a more useful related answer for the latter: How to order distinct tuples in a PostgreSQL query; Basics for DISTINCT ON: Select first row in each GROUP BY group? Well, the ORDER BY is needed to keep those rows together that share the same value for the "distinct columns". rowNumber = c2. You can order by a selected column or other expressions. collect(&:name)) Mar 9, 2018 · When called on one column it gives back only distinct values of that column. (The question is old, but comes high in Google results for “sql distinct is not a function” (second, first of Stack Overflow) and yet is still missing a satisfying answer, so) Actually this is the ordinary DISTINCT qualifier on a SELECT -- but with a misleading syntax (you are right about that point). I correctly get 11 rows. SELECT DISTINCT ON (donorig_cdn) donorig_cdn,cerhue_num_rfa,cerhue_dt. picture_id = p. FROM t_certif_hue. ORDER BY datetime DESC. Syntax: SELECT DISTINCT column_1 FROM table_name; Lets query Postgres Select Distinct id values from our table tutorials using distinct queries in PostgreSQL. See: PostgreSQL DISTINCT ON with different ORDER BY; Or similar, depending on your exact situation and requirements. ( select col2. Simple solution. It can also be used for finding distinct values on one or more columns. ) ; CREATE TABLE table_b. select_list. atable WHERE col_a IS NOT NULL UNION SELECT col_b as value FROM aschema. ) sub. There may be sophistication to get best results. DISTINCT is never a function Nov 11, 2016 · For the documentation: If DISTINCT is specified in addition to an order_by_clause, then all the ORDER BY expressions must match regular arguments of the aggregate; that is, you cannot sort on an expression that is not included in the DISTINCT list. (. 5. It is very important that the order by be consistent with the distinct on keys: SELECT DISTINCT ON (e. It is entirely based on what you ORDER BY. The ORDER BY ensures that status = 'success' is sorted before 'fail', and hence 'success'is selected if present: SELECT DISTINCT ON (userid) userid, status FROM my_table ORDER BY userid, status DESC; Jan 24, 2023 · 1. "key" FROM testTable as t; Jan 25, 2021 · Three is just a number I used to illustrate the example - what I'm trying to achieve is get all the data concerning the last X distinct itemids - let me illustrate with examples - suppose the itemids are articles and the rows in this table represent comments on articles, I would like to obtain all the comments (rows) made on the most recent X articles. Mar 3, 2017 · This will give you 'Mango' followed by the others in order; WITH get_rows AS (SELECT DISTINCT item_type FROM the_item) SELECT item_type FROM (SELECT 1 as seq, item_type FROM get_rows WHERE item_type = 'Mango' UNION ALL SELECT 2 as seq, item_type FROM get_rows WHERE item_type <> 'Mango') ORDER BY seq, item_type The subqueries effectively act as temporary tables or views for the duration of the primary query. SELECT *, row_number() OVER (PARTITION BY some_field) AS rn. The columns in SELECT DISTINCT ON must align with the initial columns in the ORDER BY clause. E. Mar 1, 2014 · full outer join. Assume this set of rows: c1 | c2 ---+---- 1 | 100 2 | 10 1 | 200 2 | 15 Oct 21, 2015 · works until it hits a duplicate, the I get the violates primary key message. IsGen = 1 THEN 1 ELSE 2 END Sep 18, 2023 · That’s where the ORDER BY clause comes in! Let’s dive right in. To retrieve rows that satisfy a specified condition, you use a WHERE clause. You can only define an alias for an expression in the actual select list, and the () is not part of the select list, but part of the distinct on expression. good = p. incidentnumber) incommingtickets. station_id ORDER BY submitted_at DESC NULLS LAST LIMIT 1 ) l; Jan 29, 1999 · Anyway, to answer Thomas' question, the way SELECT DISTINCT is implemented is that first there's a sort on the DISTINCT columns, then there's a pass that eliminates adjacent duplicates (like the Unix uniq(1) program). tag_id IN (1,2) GROUP BY p. FROM (. It's worth noting that it might be solved today as follows: SELECT country, food_id FROM (SELECT country, food_id, ROW_NUMBER() OVER (PARTITION BY country ORDER BY freq DESC) AS rn FROM ( SELECT country, food_id, COUNT('x') AS freq FROM country_foods GROUP BY 1, 2) food_freq) ranked_food_req Dec 26, 2015 · SELECT array_to_string(array_agg(animal_name),';') animal_names, array_to_string(array_agg(animal_type),';') animal_types FROM (SELECT animal_name, animal_type FROM animals) AS x; The input to the array_agg would then be unordered but it would be the same in both columns. For the same reason, standard SQL doesn't allow you to have ambiguous columns in a query with GROUP BY. This will also require 4 table scans (and no use of indexes). This is a possible (not working) query: SELECT "id", "value" AS "t". Paul A Jungwirth. name AS source, e. WHERE W. modified_time, e. ORDER BY p. text, e. uuid. IsGen = 0 THEN 0 WHEN tbl_Bill. As stated earlier, the crosstab must have three columns. atable WHERE col_b IS NOT NULL UNION SELECT col_c as value FROM aschema. , row_number() over (order by col2) as rowNumber. song Nov 23, 2009 · I want to select all distinct order_ids from my table, and order that list by the date column. station_id WHERE aa. Here I started my ORDER BY clause Dec 18, 2023 · 1 SELECT 2 DISTINCT column x, column y 3 FROM 4 table_name; Now, let us analyze the syntax. It always applies to all columns in the select list. the_date AS pricing_date, i. ORDER BY upper(my_column) You can even choose which of the results you get, by adding another column to the ORDER BY clause to make the desired result appear first: SELECT DISTINCT ON (upper(my_column Nov 9, 2020 · DB::select('select distinct on (slug) slug, uid from comments'); This will fetch a list of slug, uid stdClass pairs with random uid for each slug. Feb 1, 2017 · Maybe with an index over each of the three column I can simply select independently the three columns like that: SELECT DISTINCT value FROM ( SELECT col_a as value FROM aschema. If you want to retrieve distinct values for only one column while still displaying other columns, you can use aggregate Aug 25, 2020 · Use SELECT DISTINCT ON, which provides a simple and readable method to get the rows unique on userid. incidentnumber. Multi select in general can be executed safely as follows: select distinct * from (select col1, col2 from table ) as x. edited Oct 1, 2013 at 12:07. Conclusion. Sep 2, 2019 · Use DISTINCT ON (): SELECT DISTINCT ON (timestamp, symbol) timestamp, symbol, close, open, high, low FROM mv_qs_facts; This will return close, open, high and low for a random member of the group. the_date >= p. (87 ms, 117 ms) SELECT DISTINCT a AS abcd. Give me results for persons [1, 2, 3] Which should result in rows with ids 2, 3 and 4. Note that DISTINCT ON can also be turned into an equivalent query with GROUP BY; in this case, SELECT email, MIN(created_at) as created_at FROM subscriptions GROUP BY email. Mar 15, 2014 · WHERE (city > '') AND (number_id = 123) GROUP BY city, state, country ORDER BY MAX(occured_at) ASC. maxcreated, b. station_id = bb. If you want to prefer rows with a non- NULL col3, just include that in your ordering: SELECT DISTINCT ON (col1, col2) ORDER BY col1, col2, col3 ASC NULLS LAST. For example, to select the ‘name’ column from a table ‘users’, you would write: SELECT name FROM users; This will return a result set containing only the names of the users. Which is more efficient will probably vary, although ready-sorted sub-query from the DISTINCT ON seems to give some advantage to the sort needed by the Window function. discount percent. Jan 6, 2024 · SELECT DISTINCT ON (column1) column1, column2 FROM table_name ORDER BY column1, column2 DESC; This query not only selects distinct rows based on column1, but it also sorts the results by column1 in ascending order and column2 in descending order. good AND i. 3k 15 77 94. SELECT DISTINCT ON (plz,the_geom) the_geom Any ideas where I am thinking wrong? I am using postgreSQL 9. The following illustrates the syntax of the ORDER BY clause: SELECT. id), e. Using DISTINCT is of course a query-wide parameter, so trying something like this doesn't work: SELECT DISTINCT(orderId, datetime) FROM table. . id = my_table. Aug 18, 2021 · In PostgreSQL (but not many other databases), you can use a DISTINCT ON clause: SELECT DISTINCT ON (upper(my_column)) my_column. As to your database management system: PostgreSQL is very good; I see no reason why you would change it for another. Jun 24, 2017 · For only 400 stations, this query will be massively faster:. edited Mar 2, 2014 at 16:59. The DISTINCT keyword will then operate on the particular column (s) in question and then filter out the duplicate to produce a From what I understand, this isn't possible, since the distinct on needs to match what I order by. 3. UNION ALL. It’s important to note that the DISTINCT operation applies to all selected columns together. id, e. Id_Theme = G. the_date, p. So you need to do something a bit more complex: SELECT Id_Category, Id_Theme, (SELECT Id FROM Words W. distinctのみでは、単一のカラムが出てきてしまう。. FROM weather_reports. Jan 27, 2017 · So this works: SELECT *. However, when I run: SELECT DISTINCT COUNT(thing) FROM tablename WHERE condition. FROM ( SELECT bb. The PSQL SELECT DISTINCT statement can be used to fetch the unique column values of fore_color from the colorproperties table. Then the limit will be applied on number of rows of Person then. Id_Category = G. duplicate_entries) as de where de < ds. station_id, l. The best way to do this in Postgres is to use DISTINCT ON: SELECT DISTINCT ON (fkey) id, fkey, srno. The database processes them sequentially discarding all subsequent rows from the same set. – In PostgreSQL, the DISTINCT clause is used with a SELECT statement to remove duplicate rows from a result set. *. Postgres' current behavior is clearly wrong IMHO, but there isn't a unique definition of right behavior, because it's not clear which tuples should get selected for the sort. The Takeaway. Syntax. JOIN titles ON titles. I think it's just a matter of bad wording on that tutorial page, and should read: select distinct on (column1) To sort the rows of the result set, you use the ORDER BY clause in the SELECT statement. The last two columns are the category and value columns. song_id, MAX (bb. It allows you to query and retrieve specific columns and rows of data based on your criteria. SELECT A AS val FROM yourTable. Each subquery can be a SELECT, TABLE, VALUES, INSERT, UPDATE, DELETE, or MERGE statement. Consider my comment. I get 23 for the total count. ポイント. ORDER BY events. created_at) AS maxcreated FROM follows aa INNER JOIN broadcasts bb ON aa. Jul 18, 2014 · Or your example may be a simplification of a more complex query, or you really want to GROUP BY / DISTINCT ON a few selected columns only. The general processing of SELECT is as follows: All queries in the WITH list are computed. Although its working, it is returning the first index_id for each level, i would like to get the highest index_id in each distinct level. SELECT DISTINCT ON (the_geom,plz) the_geom and . Jul 28, 2021 · Clicking refresh so fast I went with your first draft that had SELECT DISTINCT ON (m. priority, CAST(e. edited Dec 28, 2017 at 15:48. In the original query, the first join Dec 6, 2023 · WITH titles AS (. FROM table1. NULL. LIMIT 3. 24. As posted by the upvoted answers, SELECT DISTINCT ON (a) a, b FROM the_table ORDER BY a, b DESC works on Postgre 12. FROM. SELECT DISTINCT title, id FROM my_table. SELECT B FROM yourTable. To do this, you need to use an aggregate function to sort on, and use a GROUP BY to make the DISTINCT work. the_date) i. Sep 18, 2018 · 2. Select only the DISTINCT values from the country column in the customers table: SELECT DISTINCT country FROM customers; Run Example ». Jul 10, 2018 · 2. the_date ORDER BY i. SQL Fiddle. INSERT INTO Table_A (colA, colB, colC, colD, colE) SELECT DISTINCT colA, colB, colC, columnD, colE FROM Table_B; . I have tried. If you don't have the Person table and can't modify the DB, what you can do is use SQL and Group By PersonId, and concatenate colors. You have selected the distinct column in the subquery but the where clause gets all those columns with that value. creation_time, Mar 16, 2016 · 9. Like: SELECT movie, string_agg(actor, ', ' ORDER BY actor) AS actor_list FROM tbl GROUP BY 1; But it's typically faster to sort rows in a subquery. ORDER BY id -- or by other column. You can use SELECT with DISTINCT to find only the non-duplicate values from column “col1”: postgres=# select distinct(col1) from test order by col1; col1 ----- 1 2 3 (3 rows) 2. The columns x and y in the syntax above represent the particular column from which you would want to remove duplicate results. The ORDER BY clause allows you to sort rows returned by a SELECT clause in ascending or descending order based on a sort expression. ①distinctではなく、distinct onを使う。. order by tn1. DB::select('select distinct on (slug) slug, uid from comments order by slug, uid desc'); (so much cleaner and easier to read than using a query builder) But if you really want to, you can do this: SELECT p. Try this solution: SELECT a. from ( select distinct col2 from mytable ) x ) as c2. So, in your query it's impossible to inlcude Id in the select list. It keeps only one row out of two or more duplicate rows. Id_Category AND W. Sep 4, 2015 · As you've discovered, standard SQL treats DISTINCT as applying to the whole select-list, not just one column or a few columns. Each execution of the query can return different rows. This comes in super handy when you’re dealing with large sets of data and need your results to be in a more understandable or manageable order. [] Note that the "first row" of each set is unpredictable unless ORDER BY is used to ensure that the desired row appears first. id INTEGER NOT NULL PRIMARY KEY, name TEXT, logo TEXT. Sep 10, 2008 · 10. EDIT: if you have large amount of data in this table you can further optimize the query to limit and skip unique titles first then get their id: Jun 27, 2024 · The subqueries effectively act as temporary tables or views for the duration of the primary query. I'm definitely not fully understanding how the group/distinct/joins all work together. SELECT retrieves rows from zero or more tables. What is the ORDER BY Clause? The ORDER BY clause is your go-to SQL tool for sorting the result set of a query by one or more columns. A WITH query that is referenced more than once in FROM is computed only once. Id_Theme. Here an example, how to order by the result of a case-statement: SELECT col1 , col2 FROM tbl_Bill WHERE col1 = 0 ORDER BY -- order by case-statement CASE WHEN tbl_Bill. When writing a data-modifying statement ( INSERT, UPDATE or DELETE) in WITH, it is usual to include a RETURNING clause. Having both events. Use the ORDER BY clause if you want to select a specific row. Even though the customers table has 91 records, it only has 21 different countries, and that is what you get as a result when executing the SELECT DISTINCT statement above. What happens when we use it with multiple columns and should we ever do this? Unrelated, but: a common misconception that I see is that distinct (col1), col2 is something different than distinct col1, col2. When writing a data-modifying statement ( INSERT, UPDATE, DELETE, or MERGE) in WITH, it is usual to include a RETURNING clause. FROM incommingtickets. For example, consider the following table with two columns, key and value: key value === ===== one test one another one value two goes two here two also three example Jun 15, 2016 · SELECT DISTINCT ON (id) id, status, source FROM data ORDER BY id, status Here is an aequivalent query that does not use any Postgres specific features: SELECT id, status, source FROM (SELECT id, status, source, row_number() OVER (PARTITION BY id ORDER BY status) AS n FROM data) AS sub WHERE sub. columns. So, all you need is an order that ensures the latest entry comes first. id from dupe_set ds where not exists. The basic syntax of a SELECT statement in PostgreSQL is as follows: SELECT DISTINCT ON (language) id, language FROM programming_languages ORDER BY language; This way, you can fetch more than one column and get the unique values based on a specific column. Where for each instance the name of the column is determined from the value of key while the value is the value of the column value, not knowing what kind of values will be provided by the column key. unit_diag_history ) as dt where rank = 1 You might want to add something to the ORDER BY to consistently break ties as well but that wouldn't alter the overall technique. It keeps one row for each group of duplicates. sql. atable WHERE col_c IS NOT Apr 8, 2020 · Now that I'm in Postgres, this query does not work and gets a: ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list LINE 12: sortorder ^ SQL state: 42P10 Character: 135 Doing this however returns duplicates because there are additional fields not listed here that make that entire record unique. group(T. So there you have it, everything you need to know to get started with SELECT DISTINCT and SELECT DISTINCT ON in PostgreSQL PostgreSQL DISTINCT ON with different ORDER BY; SELECT * FROM ( SELECT DISTINCT ON (col1) col1, col2, col3 FROM test ORDER BY col1, col3 DESC ) sub ORDER BY col3 DESC, col2; Assuming that col2 functionally depends on col1, so we can ignore it in DISTINCT ON and ORDER BY of the inner query. id, my_table. FROM my_table. I need to query an SQL database to find all distinct values of one column and I need an arbitrary value from another column. The DISTINCT ON expressions are interpreted using the same rules as for ORDER BY (see above). May 30, 2018 · 4. What I want is to get the above table, but without row 4, since it will sort on symbol and value ascending, and then distinct and choose the first row in that sorted table. distinct (a),b is the same as distinct a,(b) or distinct a,b and it's completely unnecessary if you combine it with group by – Let's say this is the sample date coming from a join of 2 tables. Note that the "first row" of each set is Jun 28, 2017 · If you want it easier, you'll have to write the records, so there are no gaps. Aug 30, 2014 · select unit_id, time, diag from ( select unit_id, time, diag, rank() over (partition by unit_id order by time desc) as rank from diagnostics. submitted_at, l. start and events. price FROM inventory i LEFT JOIN price p ON i. This returns all DISTINCT combinations of the orderId and datetime, so I'm left with May 2, 2016 · I want to sum the values of column 'type', but the value of column 'id' should be distinct. (select de from unnest(ds. user_id = 2 GROUP BY bb. But I need to support getting a list of one contact method each for a list of people in a single query. ) t; The SELECT statement returns all rows from one or more columns in a table. created_date. I get a different number of rows for. -- derived table giving distinct values of col2 and a rownumber column. g. answered Mar 1, 2014 at 10:40. Within each result row, the most recent (highest value) for column b would be picked. The source_sql first column is used as the row_name. This example uses the SELECT statement to find the first names of all customers from the customer table: SELECT first_name FROM customer; Code language: SQL (Structured Query Language) (sql) Here is the partial output: first_name. Oct 4, 2017 · The snippet from the Official documentation for PostgreSQL is as follows DISTINCT ON ( expression [, ] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. select string_agg (distinct a || '-' || b, ',' order by a || '-' || b) from a_table; or Apr 25, 2017 · PostgreSQL introduced support for window functions in 8. id. If you start adding more columns to your grouping with something like this: T. The SELECT ALL is the default clause specified which keeps all rows from the result set. If I add a distinct clause like, SELECT DISTINCT ON (incommingtickets. Solution: Make sure the initial columns in your ORDER BY match the columns in your SELECT DISTINCT ON expression. e. Jan 6, 2024 · Basic Selection. If you want one row per distinct e. FROM yourTable. f. Enclosing one of the columns with parentheses won't change anything and is useless. Try something like this: SELECT DISTINCT Category, MAX(CreationDate) FROM MonitoringJob. Mar 17, 2019 · If in doubt, read the manual. Sep 24, 2009 · SQL> select distinct deptno, job from emp 2 order by deptno, job 3 / DEPTNO JOB ----- ----- 10 CLERK 10 MANAGER 10 PRESIDENT 20 ANALYST 20 CLERK 20 MANAGER 30 CLERK 30 MANAGER 30 SALESMAN 9 rows selected. Dec 1, 2018 · 8. I'm on Postgres 14 if that makes any difference May 21, 2014 · The undecorated SELECT DISTINCT ON selects one row for each group but you don't know which of the rows will be selected. The following statement will help execute this. The parentheses won't change anything. サブクエリで重複なくしたレコードを生成。. SELECT s. 4, the year after this question was asked. Rory. Note I converted the LEFT JOIN to INNER JOIN. One simple approach is to use a union: SELECT DISTINCT val. incidentnumber = opentickets. However, I am posting this answer to highlight few important points: The results will be sorted based on column a; not column b. If we do that, we’ll get an error, like this: SELECT DISTINCT ON(FirstName, Age) * FROM Dogs ORDER BY DogId, FirstName, Age; Result: SELECT DISTINCT ON expressions must match initial ORDER BY expressions. ) SELECT my_table. id product_id invoice_id amount date 1 PROD1 INV01 2 01-01-2018 2 PROD2 INV02 3 01-01-2018 3 PROD1 INV01 2 05-01-2018 4 PROD1 INV03 1 05-01-2018 5 PROD2 INV02 3 08-01-2018 6 PROD2 INV04 4 08-01-2018 Oct 1, 2013 · I am using the following pgsql query to select index_id and making a distinct query on the level column. Dec 8, 2020 · select * from (select distinct on (id) * from テーブルA) subA order by 時間; 手順1. WHERE rn = 1; If, from each set with identical some_field, any row is good, you are done here. ORDER BY fkey, srno DESC; 1) Using PostgreSQL SELECT statement to query data from one column example. LEFT JOIN opentickets. For example: I want to sum the values of type(a,b,d) into one column me1 and values of type(c,e,f,g) to another column me2, but those values should be summed which have distinct ids. As this can work on most of the DBMS and this is expected to be faster than group by solution as you are 19. Jan 11, 2016 · PostgreSQL have very nice syntax for this types of queries - distinct on: SELECT DISTINCT ON ( expression [, ] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. PostgreSQL uses the SELECT DISTINCT clause to return only unique values from a query’s result set. Each subquery can be a SELECT, TABLE, VALUES, INSERT, UPDATE or DELETE statement. 1. If the rows weren't sorted, this wouldn't be easily possible. – Jun 26, 2015 · However, I cannot determine the correct syntax to both select distinct on the 5 primary key columns used in Table_A, and select all ten columns to be inserted. 6. FROM pictures p. When I run: SELECT DISTINCT thing FROM tablename WHERE condition. title FROM my_table. The syntax of the PostgreSQL WHERE clause is as follows: SELECT select_list FROM table_name WHERE condition ORDER BY sort_expression; Code language: SQL (Structured Query Language) (sql) Aug 18, 2017 · With JPA, you should do the query on Person table (one side), not on the PersonColor (many side). So the query is as good as writing 'select * from table' unless 'field' column is a unique column in which case the distinct on that column isn't required at all. No need for grouping. created_date, string_agg(pt. Nov 21, 2018 · 12. As isapir commented, you can add an ORDER BY clause in the aggregate call to get a sorted list - should you need that. Example. To select a specific column, use the SELECT statement followed by the column name. Mar 1, 2022 · distinct is not a function. id asc) select ds. id) Selects the lowest number ID's that have duplicates (assuming the ID is increasing int PK). SELECT with DISTINCT can also be used in an SQL inline query: The subqueries effectively act as temporary tables or views for the duration of the primary query. Nov 7, 2012 · How is it possible that the order of columns matter in a distinct. is that it's not real clear how the combination of SELECT DISTINCT on one column and ORDER BY on another *should* work. order_number AS integer), s. uuid in the distinct clause will mean the set of the two is unique, but if uuid is already unique per event row, then adding other columns from the events table to the distinct on clause should not change the Sep 22, 2013 · SELECT DISTINCT ON (object_id) object_id, event_timestamp ---, more columns FROM test_select ORDER BY object_id, event_timestamp DESC ; If you want the results ordered by event_timestamp DESC and not by object_id , you need to include it in a derived table or a CTE: Jan 31, 2023 · I can't seem to find any combination of sub queries or window functions where I can meet all the goals: get the distance/title, only show one row per deal id, and order by deals. The reason for this is that it's ambiguous what value to put in the columns you exclude from the DISTINCT. id, then you are looking for distinct on. Mar 2, 2024 · Step 4) The Select DISTINCT in PostgreSQL clause can be used to remove duplicate rows from the result. It only returns the first row found for each value of the given column. It does not mention an alias there. postgresql. SELECT DISTINCT ON (level) index_id FROM indexes. See: Create array in SELECT If you want to order results in a different way (like commented), you'll have to wrap the query in an outer query with a second ORDER BY. SELECT DISTINCT(id) FROM tutorials Oct 27, 2023 · In other words, we can’t start the ORDER BY clause with a column that isn’t passed to DISTINCT ON(). Database is Postgres 9. answered Mar 16, 2016 at 15:38. That's assuming you want the results ordered by the MOST RECENT occurrence. These effectively serve as temporary tables that can be referenced in the FROM list. SELECT DISTINCT ON (i. Postgres has SELECT DISTINCT ON to the rescue. Not bad efficiency when the values are few, and with more values becomes the fastest in my (not extensive) test: -- Query 2. Nov 14, 2022 · To sort resulting (distinct) rows by created_at DESC, you have to run an outer SELECT with a different sort order: SELECT * FROM ( SELECT DISTINCT ON (label) * FROM products ORDER BY label, created_at DESC ) sub ORDER BY created_at DESC; See: PostgreSQL DISTINCT ON with different ORDER BY Use the DISTINCT ON clause to keep the first unique entry from each column or combination of columns in a result set. INNER JOIN picture_tags pt on pt. rowNumber. The general answer to your question is that when using DISTINCT ON (x, ) in SELECT statement in postgresql, the database sorts by the values in the distinct clause in order to make it easy to tell if the rows have distinct values (once they're ordered by the values, it only takes one pass for the db to remove duplicates, and it only needs Sep 9, 2013 · It very much depends on circumstances and exact requirements. So try. Jul 29, 2021 · 2. GROUP BY Category. Mar 16, 2015 · When you use GROUP BY you cannot include in the select list a column which is not being ordered. eventuuid = events. Else, implement your priority with ORDER BY in the OVER clause. Paritosh. There are only 11 distinct things out of the 23 total rows. – The source_sql contains the select statement that returns the source set of data. uuid; But just in a different order. id) instead of combined_id, which yielded the same ~300 rows 😂 The new version worked perfectly. I have the following problem: Assuming the table TEST as follows: ID NAME ----- 1 Alex 2 Oliver 1 Thomas 2 Fenella SELECT DISTINCT ON id id, name FROM test; produces: ID NAME ----- 1 Alex 2 Oliver SELECT DISTINCT ON id, name FROM test ORDER BY name; produces: ID NAME ----- 1 Alex 2 Fenella 1 Thomas I would have expected only two rows in both queries. tag_id, ',') as tag_ids. good, i. Jul 7, 2012 · If you follow stations that are both getting a song broadcasted at the same time, those broadcasts have the exact same timestamp. ON incommingtickets. In the current backend, doing an ORDER BY on another column overrides the sorting on the DISTINCT columns, so when the duplicate May 25, 2011 · That won't do the job. SELECT DISTINCT ON (location) location, time, report. One of the columns is called thing. If your DBMS doesn't support distinct with multiple columns like this: select distinct(col1, col2) from table. Aug 14, 2023 · The DISTINCT clause is useful when you want to identify unique values or create summary reports without duplicate entries. n = 1 Description. These would be the ID's that you would keep around. good, p. Is it unique to Postgres? – Mar 4, 2015 · SELECT distinct on (column_a, column_b) COLUMN_A || ' - ' || COLUMN_B, COLUMN_A, COLUMN_B FROM TABLE_A order by column_a, column_b The above will only work in Postgres. Or use a programming language rather than SQL for calculation. fm ef ss fp bk cr ih rj au gc