I am trying to restrict the number of rows selected in kogrid to 25 as page size is more than 25 records. I tried implementing beforechange, but it didn't work for me.
Can anyone please help me on this?
In general limiting a user while he selects rows is not a good idea. Try to warn user or block subsequent operations (like "Too many rows selected. Select not more than 25."). Write the warning in a kind of "status line". And don't try to block selection.
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I want to create a SQL Server table that has a Department and a Maximum Capacity columns (assume 10 for this scenario). When users add them selves to a department the system will check the current assignment count (assume 9 for this scenario) in the department and compare it to the maximum value. If it is below the maximum, they will be added.
The issue is this: what if two users submit at the same time and the when the code retrieves the current assignment count it will be 9 for both. One user updates the row sooner so now its 10 but the other user has already retrieved the previous value before the update (9) and so both are valid when compared and we end up with 11 users in the department.
Is this even possible and how can one solve it?
The answer to your problem lies in understanding "Database Concurrency" and then choosing the correct solution to your specific scenario.
It too large a topic to cover in a single SO answer so I would recommend doing some reading and coming back with specific questions.
However in simple form you either block the assignments out to the first person who tries to obtain them (pessimistic locking), or you throw an error after someone tries to assign over the limit (optimistic locking).
In the pessimistic case you then need ways to unblock them if the user fails to complete the transaction e.g. a timeout. A bit like on a ticket booking website it says "These tickets are being held for you for the next 10 minutes, you must complete your booking within that time else you may lose them".
And when you're down to the last few positions you are going to be turning everyone after the first away... no other way around it if you require this level of locking. (Well you could then create a waiting list, but that's another issue in itself).
Thanks in advance for putting up with me.
Pulling a 33,000-record recordset from the database took LESS execution time than using Count() in the SQL and just grabbing 20 rows.
How is that possible?
A bit more detail:
Before, we were grabbing the entire recordset yet only displaying 20 rows of it on a page at a time for pagination. That was cringeworthy and wasteful, so I redesigned the page to only grab 20 rows at a time and to simply use an index variable to grab the next page, and so on.
All well and good, but that lacked a record count, which our people needed.
So after the record query, I added (what I thought would be) a quick query just on the index of the table using the Count(index) function in Structured Query Language.
A side by side comparison of the original page and my new page indicates my new page takes roughly 10% longer to execute than the original! I was flabbergasted. I thought for sure it would be lightning fast, way faster than the original.
Any thoughts on why and what I might do to remedy that?
Is it because the script has to run two queries, regardless of the data retrieved?
Update:
Here is the SQL.
(Table names and field names are fictionalized in this post for security, but the structure is the same as the real page).
The main recordset select query contains:
SELECT
top 21 roster_id, roster_pplid, roster_pplemailid, roster_emailid, roster_firstname,
roster_lastname, roster_since, roster_pplsubscrid, roster_firstppldone, roster_pmtcurrent,
roster_emailverified, roster_active, roster_selfcanceled, roster_deactreason
FROM roster
WHERE
roster_siteid = 22
AND roster_isdeleted = false
order by roster_id desc
The record count query contains:
SELECT
COUNT(roster_id)
FROM
roster
WHERE
roster_siteid = 22
AND roster_isdeleted = false
The first query runs, then the second. The second always dynamically has the same matching WHERE filter.
I think I know why it is slower, I'm using GetRows to grab the recordset in the new page, was not using that in the old page. That seems to be the slowdown. But I have to use it, cannot step beyond the 21st record otherwise.
Nick.McDermaid : The SQL shown is selecting the TOP 21 rows, that is how it is grabbing just 20 rows (number 21 is just to populate the index for the "Next" page link).
"meta/background about the use of code and person using it"
1.site built by professional that left company,
2.I am inexperienced but trying/ want to learn,
3.Customer support site for service reps,
................................................
What im trying to do exactly per stackoverflows parameters.
We have a drop down box listing issues that the customer had in a column labeled "issue_type". I can export via csv entire table load onto excel then give to boss for overall review of what the issues were. However data base has a "hide" column. Its function is that when the row is updated the record is kept but the same "job or call" has only one viewable report on site (the most recently updated one). Hide is a boolean. In conclusion I want to export rows that only has the "hide" column Boolean status at 0, AND to only export the columns "customer", and "issue_type". I can seem to only do one or the other. and have researched a minimum of 4 hours to find answer myself and cannot find a syntax to do both at the same time with phpmyadmin.
I dont want an enormous data that is mostly useless but for issue type and customer but i will have to manually delete all the rows with hide = 1?
Thanks anyone 1st attempt question sorry if not correct for stackflow.
SELECT Customer,Issue_type FROM tickets where hide =0;
Elaborating on what is above for anyone that may be looking for a similar answer, SQL supports the "where" clause of which you can when properly syntaxed select many of your columns and their associated strings, booleans, and numbers to = what your looking for. Wildcards I found later for other uses work as well.
Sorry about the self answer but hopefully someone finds this usefull
I have an access form with few controls on it, like start-date, end-date, move_type, mover_name etc, when user fills this field n clicks on query command button, a select query is run and it fetches records from various tables depending upon the criteria mentioned by the user.
Later the same records are exported to excel file and a report is generated for user.
Now I need to do more with this, my select query has a field "quoted-price", depending upon the price quoted the records need to be sorted out.
EX : if quoted_price < 500 then it is a "domestic apartment1", if quoted-price is >500 And <1500 it is "domestic Apartment1" etc.
Now I need to do more with this, my select query has a field "quoted-price", depending upon the price quoted the records need to be sorted out.
EX : if quoted_price < 500 then it is a "domestic apartment1", if quoted-price is >500 And <1500 it is "domestic Apartment1" etc. and when all the records generated through select query are searched on this criteria, the records need to be grouped accordingly. Later the count for individual category is multiplied by a unit value and total charge is calculated.
I tried building many queries to do this and tables to refer to value but of no use. Any help will be much appreciated.
are you looking to create a new field depending on the condition? That may be step one of what you are trying to do, If so that is pretty easy. See here: http://allenbrowne.com/casu-14.html
Hello I need a SQL query statement that gets me rows 'start' to 'finish'.
For example:
A website with many items where page 1 selects only items 1-10, page 2 has 11-20 and so on.
I know how to do this with Microsoft SQL Server and MySQL but I need an implementation that is platform independent. :/
I have an Increment line for IDs but deleting in-between will mess the result when I select via
WHERE ID > number AND ID < othernumber
of course
Is this possible without fetching the whole database to a ResultSet?
I think your safest bet would be to use the BETWEEN operator. I believe it works across Oracle/MySQL/MSSQL.
WHERE ID BETWEEN number AND othernumber
Concerning your comment " I was just think for the case when first 100 IDs are gone I'll have to check further until there is something to fetch", you might wanna consider NOT actually ever deleting stuff from your database but to add a flag like "active" or something like that to your tables so you can avoid situations like the one you're now trying to avoid. The alternative is where you are now, having to find the max and min rows in a filter