You can use row_number() to get the row number of the row. It uses the over command – the partition by clause specifies when to restart the numbering and the order by selects what to order the row number on. Even if you added an order by to the end of your query, it would preserve the ordering in the over command when numbering. I used this way to take the last record for each user that I have on my table.
All the conditions are in one place and the rows to update are in another place. You then have a table of users to disable (blacklist) at one go because you find out they’ve all done something bad. You’ll get the best performance if you forget the where clause and place all conditions in the ON expression.
How do I programmatically set the value of a select box element using JavaScript?
- Connect and share knowledge within a single location that is structured and easy to search.
- This is in fact a terrifically simple solution for most cases.
- For me this was preferable because I didn’t need to “try” to parse and I also want the result inline without generating an output variable.
- And also you need to have the following line defined in your xml configuration.
- In eduffy’s answer, the accent symbol is (presumably accidentally) placed as the delimiter for the string instead of replacing the apostrophe in O’Brian.
In eduffy’s answer, the accent symbol is (presumably accidentally) placed as the delimiter for the string instead of replacing the apostrophe in O’Brian. This is in fact a terrifically simple solution for most cases. Eduffy’s idea to add a backtick is a good one; it’s just backward in their provided code example. Either in JavaScript or in SQLite, you can replace the apostrophe with the accent symbol. If you need to base your conditional logic on more than one column you can use DataFrame.apply() as others suggest.
Query
The apostrophe character can be inserted by calling the CHAR function with the apostrophe’s ASCII table lookup value, 39. The string values can then be concatenated together with a concatenate operator. You want to check for ””, and replace them if they exist in the string with ””” in order to escape the lone single quote. However, by giving it more conditions it can “skip” every row we’re not updating.
But you can achieve this in just one line.Please try following declaration and you will get all the comma separated values in a String list. This uses a common table expression (CTE) to assign a unique rn (row number) to each record for each user, based on the user_id and sorted in descending order by date. The final query then selects only the records with rn equal to 1, which represents the most recent record for each user.
(Excel) Conditional Formatting based on Adjacent Cell Value
That ConversionService will be picked up by Spring and then used whenever a type conversion needs to be value reporting form performed by the framework. … If no ConversionService is registered with Spring, the original PropertyEditor-based system is used. As I understand, an alternative of doing this is to have it in the Spring config file, and load it as a bean reference (correct me if I’m wrong), i.e.
- Instead, we can move all the where clause conditions into the join, and internally, remove the second query completely.
- This uses a common table expression (CTE) to assign a unique rn (row number) to each record for each user, based on the user_id and sorted in descending order by date.
- I have a table that is a collection entries as to when a user was logged on.
- This one should give you the correct result for your edited question.
It has some memory overhead since it buffers a dictionary. If you are using Spring Boot 2, it works as is, without any additional configuration. In a Spring application, you typically configure a ConversionService instance per Spring container (or ApplicationContext).
Second option (not working)
And so on.So this is an easy way of passing the value to another page (with select option list) through GET in url. Inner Query will return the latest date for the current user, Outer query will pull all the data according to the inner query result. It might not work so well on large tables, even with good indexing. Performance seems to be ok however it requires a bit of boilerplate code setup. I used class (strongly-typed version of Enum with parsing and performance improvements). I found it on GitHub, and it should work for .NET 3.5 too.
It was a query to get last location for salesman as per recent time detected on PDA devices. To get the latest record date along with the corresponding value for each user, you can use a subquery or a common table expression (CTE) in SQL. This is similar to one of the answers above, but in my opinion it is a lot simpler and tidier. The sub-query makes sure to find only rows of the latest date, and the outer GROUP BY will take care of ties. When there are two entries for the same date for the same user, it will return the one with the highest value. Additionally, as mentioned by others, performance is less than ideal for large enums, namely linear in the number of possible values.
Therefore, this is the most optimal query to avoid needless lookups of the users table… So if you have a WHERE clause here, internally, the results are getting brought back in the join and then the WHERE clause is being queried against that dataset. Instead, we can move all the where clause conditions into the join, and internally, remove the second query completely.
If your Enum had data that you wanted, return that as your Enum type. If you need to convert strings to Enums in performance-sensitive code, your best bet is to create a Dictionary at startup and use that to do your conversions. I have an HTML select tag containing the values of an enumeration. When the page is posted, I want to pick up the value (which will be in the form of a string) and convert it to the corresponding enumeration value. In Apache Commons Configuration, there is PropertiesConfiguration. It supports the feature of converting delimited string to array/list.
The short answer is to use two single quotes – ” – in order for an SQL database to store the value as ‘. In the table, one customer like John Smith can have multiple addresses.I need the SELECT query for this table to return only first row found where there are duplicates in ‘CName’. For this table it should return all rows except the 3rd (or 1st – any of those two addresses are okay but only one can be returned). And using CollectionUtils.addAll(myList, myString), you can get the list of strings. The solution provided is not working fine, since it ads the string with two single quote in database, the simplest way is to use anti back slash before the apostrophe (single quote).
This also includes C#7’s new inline out variables, so this does the try-parse, conversion to the explicit enum type and initialises+populates the myStatus variable. Because a single quote is used for indicating the start and end of a string; you need to escape it. Note, as explained in the most upvoted answer, this replaces values in the column. You need to add an UPDATE statement at first with the full address of all tables to join with, and then add the SET statement.
With these two, it even handles all the redundant whitespaces including newline, so you don’t need to add additional logics to trim them. I like it because if the conditional logic gets more complex you can move it to a function and just pass in that function instead of the lambda. You can see list contain method implementation, to understand why it works. Here is the same with an example for better understanding. But this checks the whole dataframe just to get one value, so I imagine it’s wasteful.
It will also give you the bit-type columns, and it works at least in MS Sql Server. A very simple answer if you say you don’t care which address is used. By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy. The blogpost is Enums – Better syntax, improved performance and TryParse in NET 3.5. If the default value is not an enum the Enum.TryParse would fail and throw an exception which is catched.
I would not want to experience the consequences of users, willingly or unwillingly, triggering this behavior. For me this was preferable because I didn’t need to “try” to parse and I also want the result inline without generating an output variable. And also you need to have the following line defined in your xml configuration.
This one should give you the correct result for your edited question. I see most of the developers use an inline query without considering its impact on huge data. From my experience the fastest way is to take each row for which there is no newer row in the table. I have a table that is a collection entries as to when a user was logged on.