You can order by a column not included in the select statement, and this is the logic you are looking for. (select (case when count(bedrag) > 0 then count(bedrag) end)īut the correlated subquery is unnecessary.įor the order by, just do: order by count(*) desc (case when count(bedrag) > 0 then count(bedrag) end) as aantalboetesĪctually, you could put the same case in your version as well: select spelersnr, Except where noted, these functions and operators are declared to accept and return type text. Strings in this context include values of the types character, character varying, and text. With this query, you can just do: select spelersnr, This section describes functions and operators for examining and manipulating string values. Order by aantalboetes asc, spelersnr asc The following should do the same thing, because you are already joining in the boetes table by the same column used for both aggregation and the correlated subquery: select spelersnr, count(bedrag) as aantalboetes You could easily do this on your blog.I don't think you need the subquery. This post took about 15 minutes to write. This is how I’d solve the issue, and decided to share that knowledge more widely, both to help others and also provide an example of where I might have a hiring manager ask me about this from noticing my blog. This was a post inspired by a question I saw. , ISNULL(CAST(oh.OrderID AS VARCHAR(20)), 'N/A') AS OrderIDīoth cases clean up the NULL values with something that makes more sense to a person looking at the data in a report. I could also return a string if I cast all OrderIDs to strings, as shown below. This is because the result set is a numeric, and I need these types to match. , ISNULL(oh.OrderNote, 'No orders placed') AS OrderNote Here’s a better query that replaces one value with a NA and another with a blank. I’ll use ISNULL here and in another post look at COALESCE. ISNULL is for a single expression and replaces NULL with value, while COALESCE works by returning the first non-NULL expression. format This section describes functions and operators for examining and manipulating string values. if age is NULL then I want to replace it by some text, say 'SHY' so the output is like. I can use a couple of functions to look for a NULL value in my results. pgsql-sql(at)postgresql(dot)org: Subject: replace NULL: Date: 12:00:03: Message-ID: .: Views. This works, but really, I’d like to clean up the results to show something better. Using the left join below, we see all customers with their corresponding orders. If we use an inner join, we only see customers with orders. Potentially, we have customers without orders. INSERT dbo.OrderHeader (CustomerID, OrderNote) ( OrderID INT NOT NULL IDENTITY(1,1) CONSTRAINT OrderHeaderPK PRIMARY KEY ( CustomerID INT NOT NULL IDENTITY(1,1) CONSTRAINT CustomerPK PRIMARY KEY Use this code: DROP TABLE IF EXISTS dbo.Customer This is common, where we have customers that we might add as prospects in some CRM type system. Let’s create a table of customers and orders with a few values in each. I realized this is one of those simple things that people new to SQL might not get.Īnother post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQ LNewBlogger s. PostgreSQL does not have the ISNULL function. Otherwise, it returns the result of the expression. I saw someone ask a question on how to replace NULL in a left join and decided to write a post. SQL Server supports ISNULL function that replaces NULL with a specified replacement value: ISNULL (expression, replacement) If the expression is NULL, then the ISNULL function returns the replacement.
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