Contents
How to exclude records with certain values in SQL?
I can use IN (‘1′, ’20’) for the values 1 and 20 but how to exclude if there’s also another value in Col2. (there’s no range !) Update: while it will work for non-repeated list, it may result in wrong set for table with repeated values (i.e. 1, 20, 20, 1 in column – it will still fit request if repeats are allowed, but you’ve not mentioned that).
How to create SQL distinct for only one column?
SELECT * FROM ( SELECT ID, Email, ProductName, ProductModel, ROW_NUMBER () OVER (PARTITION BY Email ORDER BY ID DESC) rn FROM Products WHERE ProductModel = 2 AND ProductName LIKE ‘CYBER%’ ) a WHERE rn = 1 This assumes SQL Server 2005+ and your definition of “last” is the max PK for a given email
Why is distinct clause not used in PostgreSQL?
The reason for this is that it’s ambiguous what value to put in the columns you exclude from the DISTINCT. For the same reason, standard SQL doesn’t allow you to have ambiguous columns in a query with GROUP BY. But PostgreSQL has a nonstandard extension to SQL to allow for what you’re asking: DISTINCT ON (expr).
When to use distinct and group by in Excel?
In other words, when several rows contain the same email, I want the results to include only one of those rows (preferably the last one). Duplicates in other columns should be allowed. Clauses like DISTINCT and GROUP BY appear to work on entire rows.
How to write an exclusion join in SQL?
It becomes hard to tell which conditions are used to join the tables ( apples.Price = oranges.Price ), and which are used to exclude results ( apples.Price = 5 ). The two are equivalent in old-style joins, but as mentioned, some joins cannot be written in this style (more on this later).
Are there disadvantages to using subqueries in SQL?
The disadvantage of using subqueries in these situations is that they may require creating many anonymous tables and probing into them. A clever optimizer could generate the same plan as a LEFT OUTER join, but since there was no such thing at the time and query optimizers were much less capable, query performance could take quite a hit.