Coldfusion query and assign rows to a session [closed] - oracle

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I have come across a strange requirement, and really haven't a clue where to begin
We have an oracle database table that will be receiving data daily, and a CF application to interface with it
What they would like is for when a user logs in, to show x amount of rows from the table, and essentially "lock" the x amount of rows to that user, so when another user logs in, their x amount of rows are different, so noone is working concurrently on the same row
What i am guessing is a session write to a table, claiming the rows, but any thoughts would be more than welcome

Answer 1

There are a few ways to approach this problem. I will take a nibble here and tell you that you will need to get into Oracle database procedures and requires you to understand locking select for update clauses which you will immerse you in the nuances of sessions and how they work in oracle and you will call it using cfstoredproc.
There is another method. Now I have no idea about your coding environment or restrictions, nor do I know the user/system load considerations so this is just a suggestion. Adding a flag field to the table and make it a bit datatype or int...whatever. You are going to select them in a cfquery, then update the list of ids (setting bitItnFlag=1 ...or whatever you want to name this new field) which will mean 'this record is checked out'. You will still have the group of records in the first query which you will loop out to the end user to work with needing an update query setting them free by setting your bitIntFlag=0. They will be essentially locked. So another user will have to select where bitIntFlag=0 essentially skipping your locked group and setting their selected group (update them equal to 1). You can use cftransaction and two cfqueries like this.
<cftransaction action"begin">
<cfquery name="selectLock" datasource="#application.dsn#">
SELECT *
FROM (
SELECT *
FROM mytable
WHERE bitIntFlag = 0
ORDER BY
dbms_random.value
)
WHERE rownum <= 10
</cfquery>
<!---Now run your update--->
<cftry>
<cfquery name="updateLock" datasource="#application.dsn#">
UPDATE
myTable
SET
bitIntFlag = 1
WHERE
primaryKeyIDthing in #ValueList(selectLock.name)#
</cfquery>
<cfcatch type="database">
<cftransaction action="rollback"/>
</cfcatch>
<cftry>
<cftransaction action="commit"/>
</cftransaction>
<cfoutput query="selectLock">
#primaryKeyIDthing#<br>
</cfoutput>
(this code is untested but should get you started if you go down this route)
When you are done you update your records using cfquery and run your update sql and set the flag to zero to free up the records.
Again this is a simple work around that may or may not work for you. I don't know what kind of transactional intensity you are dealing with in your environment but sometimes making things simple can work!