Sequentially number rows by keyed group in SQL?
SQL Server Oracle Postgres Sybase MySQL 8.0+ MariaDB 10.2+ SQLite 3.25+ This covers most bases. SELECT CODE, ROW_NUMBER() OVER (PARTITION BY CODE ORDER BY NAME) – 1 As C_NO, NAME FROM MyTable
SQL Server Oracle Postgres Sybase MySQL 8.0+ MariaDB 10.2+ SQLite 3.25+ This covers most bases. SELECT CODE, ROW_NUMBER() OVER (PARTITION BY CODE ORDER BY NAME) – 1 As C_NO, NAME FROM MyTable
PARTITION BY segregate sets, this enables you to be able to work(ROW_NUMBER(),COUNT(),SUM(),etc) on related set independently. In your query, the related set comprised of rows with similar cdt.country_code, cdt.account, cdt.currency. When you partition on those columns and you apply ROW_NUMBER on them. Those other columns on those combination/set will receive sequential number from ROW_NUMBER But … Read more
Mysql doesn’t have them, but you can simulate row_number() with the following expression that uses a user defined variable: (@row := ifnull(@row, 0) + 1) like this: select *, (@row := ifnull(@row, 0) + 1) row_number from mytable order by id but if you’re reusing the session, @row will still be set, so you’ll need … Read more
Don’t use cat or any other tool which is not designed to do that. Use the program: nl – number lines of files Example: $ nl –number-format=rz –number-width=9 foobar $ nl -n rz -w 9 foobar # short-hand Because nl is made for it 😉
In Access SQL we can sometimes use a self-join to produce a rank order. For example, for [table1] TID UserId TSource TText — —— ——- —– 412 homer foo bar 503 marge baz thing 777 lisa more stuff the query SELECT t1a.TID, t1a.UserId, t1a.TSource, t1a.TText, COUNT(*) AS TRank FROM table1 AS t1a INNER JOIN table1 … Read more
The row_number() over (partition by … order by …) functionality was added to Spark 1.4. This answer uses PySpark/DataFrames. Create a test DataFrame: from pyspark.sql import Row, functions as F testDF = sc.parallelize( (Row(k=”key1″, v=(1,2,3)), Row(k=”key1″, v=(1,4,7)), Row(k=”key1″, v=(2,2,3)), Row(k=”key2″, v=(5,5,5)), Row(k=”key2″, v=(5,5,9)), Row(k=”key2″, v=(7,5,5)) ) ).toDF() Add the partitioned row number: from pyspark.sql.window import … Read more
Not sure about the performance in big queries, but this is at least an option. You can add your results to an array by grouping/pushing and then unwind with includeArrayIndex like this: [ {$match: {author: {$ne: 1}}}, {$limit: 10000}, {$group: { _id: 1, book: {$push: {title: ‘$title’, author: ‘$author’, copies: ‘$copies’}} }}, {$unwind: {path: ‘$book’, … Read more
Well, the easiest way would be to do it at the client side rather than the database side, and use the overload of Select which provides an index as well: public List<ScoreWithRank> GetHighScoresWithRank(string gameId, int count) { Guid guid = new Guid(gameId); using (PPGEntities entities = new PPGEntities()) { var query = from s in … Read more
For the first question, why not just use? SELECT COUNT(*) FROM myTable to get the count. And for the second question, the primary key of the row is what should be used to identify a particular row. Don’t try and use the row number for that. If you returned Row_Number() in your main query, SELECT … Read more
From the Oracle docs ROWID Pseudocolumn For each row in the database, the ROWID pseudocolumn returns the address of the row. Oracle Database rowid values contain information necessary to locate a row: The data object number of the object The data block in the datafile in which the row resides The position of the row … Read more