I have problem when trying to add a row and then delete one row from a table. What I have now is:
def addItem(item:Item)={
val query = items.filter(_.name === name)
items += (item.name,item.timestamp)
if(query.list.length > 10)
{
query.sortBy(timestamp).take(1).delete
}
}
It is supposed to store 10 latest items in the database by removing the oldest if there is more than 10.
But I get an error saying
SlickException : Invalid query for DELETE statement: A single source table is required, found List((s2,Comprehension))
I do have another table in the database but this should have nothing to do with that, there is not even a relation between the two tables.
Do you have any ideas what might be wrong? Or is there another way of keeping only last 10 values in the DB. The time stamp is java.sql.timestamp and I'm using Slick library for the SQLite for scala. Also the class Item is just holding a string and a timestamp.
Thanks! Any help is appreciated!
Ok, it seems that delete doesn't work with take for some reason, as was mentioned in the comments. There doesn't seem to be any other way to select the first element of the query as query other than take. .first for example returns the actual data of the row rather than a query of the first element and therefore delete can't be applied to it.
What I did to get it working was a sort of workaround:
val oldestTime = query.sortBy(timestamp).first._2 //selects the timestamp of the oldest element
query.filter(._timestamp === oldestTime).delete // deletes all rows with that timestamp
I hope this helps someone someday.
Related
I've built a query that is coming up with some very confusing results. To start, I have a list of specific codes (varchar) that I have created a temp table using the following format:
IF OBJECT_ID('tempdb..#MentalDX') IS NOT NULL
DROP TABLE #MentalDX
CREATE TABLE #MentalDX (
MHDX VARCHAR(254))
INSERT INTO #MentalDX (MHDX)
VALUES ('F03.90'),('F03.91')....;
There are over 800 values in this table. When I use the following CASE statement:
CASE WHEN edg2.REF_BILL_CODE IN (mdx.MHDX) THEN edg2.REF_BILL_CODE
ELSE NULL
END AS mdx2
I'm always getting a NULL value. I've used = instead of IN, but it's made no difference. I know that the temp table works if I create a test query and just replace the column reference with an existing value from the table. The database shows REF_BILL_CODE is varchar(254) and I made sure to define my temp table column the same as well. Any ideas what I might be doing wrong? I can share more segments of code as well, but there will be some items I cannot do to personally identifiable information.
So, my problem was that I joined the temp table in my query. Turns out the following was actually what I was after:
CASE WHEN edg1.REF_BILL_CODE IN ( SELECT md.MHDX FROM #MentalDX md )
THEN edg1.EXTERNAL_ID
END AS mdx1
This gave me back real results instead of all NULL like before. Now I have a new problem, but will do some more research before asking that one.
I'm experiencing a really odd result when I do a count in X++, something I've not experienced before. I am performing what I thought was a really simply count query, but I can't seem to get the result I am after.
WMSOrderTrans orderTrans;
WMSOrderTrans orderTransChk;
;
select count(RecId) from orderTrans group by shipmentid where orderTrans.inventTransRefId == 'XXXXXX';
info(strFmt('Count is %1', orderTrans.RecId));
while select orderTransChk group by shipmentid where orderTransChk.inventTransRefId == 'XXXXXX' {
info(strFmt('Shipment is %1', orderTransChk.shipmentId));
}
The data set that I am selecting all have only 1 shipmentid, so the first select I am expecting a count of 1, instead I get 4 (which is how many lines for that transrefid exist). If I change the count from 'RecId' to 'ShipmentId', then instead of the count, I get actual shipmentId. I simply want it to return the count of the records, which is what I believe I've asked it to do.
I really can't see what I am missing.
In the while select, I get what I expect (the shipmentid), only 1 infolog message for the loop. This tells me that the group by with the where clause is working, but it doesn't explain why the first count select statement isn't behaving as I would expect.
For reference, this is AX2012 R1 system.
For anyone who might be interested in knowing my answer, it's tied up with Jeff's response. At the end of the day, I didn't look at data well enough, and the query returned the correct results. I initially thought there were a number of unique shipments, but I was wrong. My expected result was erroneous. There were 4 lines in the file, but the lines were unique for the item, not the shipment. They were all on the same shipment. So really, my own fault, it goes to show that one really needs to look at the data closely.
Thanks to all that responded, greatly appreciated.
I would try a database sync, then restarting the AOS. I don't see anything obviously wrong, so it points to bouncing everything.
Try getting the select statement via this method (from memory so check syntax) and then review the query against SQL directly. It uses generateOnly.
select generateOnly count(RecId) from orderTrans group by shipmentid where orderTrans.inventTransRefId == 'XXXXXX';
info(orderTrans.getSQLStatement());
If I understand what you try to achieve, you'd like to get something like this SQL query:
select count(distinct shipmentid) from orderTrans
where inventTransRefId = 'XXXXXX'
The 'distinct' keyword is not available in AX select command. The group by clause will allow you to iterate all distinct values but not to use an aggregate on top of it.
You may use a sql connection to push the exact sql command you want.
In AX, aggregate values are stores in the field used: Count(RecId), the count will go in the recid field otherwise the system may need to add new field on the buffer on the fly. I don't think you can aggregate on the group by clause as it's important to have its value.
You can try (I don't have an AX to test it) to use a query:
Query query = new Query();
QueryRun queryRun;
QueryBuildDataSource qbd;
qbd = query.addDataSource(tablenum(OrderTrans));
qbd.addRange(fieldNum(OrderTrans, InventTransId)).value("xxxx");
qbd.addSortField(fieldNum(OrderTrans, ShipmentId));
qbd.SortOrder(SortOrder::GroupBy);
queryRun = new QueryRun(query);
info(strfmt("Total Records in Query %1",SysQuery::countTotal(queryRun)));
I am new to robotframework and I am trying to get the hang of the keywords of DatabaseLibrary. I am getting error at 3 of such keywords.
1) I am using rowcount keywords as below-
${rowCount} Row Count <sql query>
And I always get ${rowCount}=0 irrespective of the number of rows in my table.
2) I am using Delete All Rows From Table as below-
Delete All Rows From Table <Table_Name>
And I get ORA-00911: invalid character but if use the same table with other keywords like Query ,it works fine.
3) I am using Table Must Exist as below-
Table Must Exist <Table_Name>
And I get ORA-00942: table or view does not exist but this table is very much there.
Please help me find what am I doing wrong.
Thanks in Advance!!!
I could be wrong but I believe a colleague told me there were issues, at the very least with the Row Count keyword.
However, for all three options there are easy solutions, which you've even hinted at in your question by using Query or Execute SQL Script
1)
${result}= Query Select count(id) from table
${rc} = ${result[0][0]} #Play with this as I forget exact syntax
2) Put your delete script in a test scripts folder with your tests and call it using Execute SQL script. You could also use Query to perform a select query before and after to confirm expected states.
3) Again perform a query against the table you're expecting to be there, a simple row count on id would do for this purpose. You could set a variable based on the result and use this again later if required.
I had similar issues.
I use cx_Oracle.
With the Table Must Exist keyword my problem was the same.
I dont really understand why, but first I have to use Encode String to Bytes keyword.
And I need to use a DatabaseLibrary 0.8 at least, because earlier versions didnt have solution for cx_Oracle. These solved this issue for me.
But with Delete all rows from table I still have problems.
Because this keyword puts a ; at the end of the line and it passes on that line to execute query if I understand weel, so it still causes an ORA-00911 error for me.
With Execute Sql String and the command DELETE FROM tablename you can have the same results, but it will work this way.
I hope it helps a little
I have a few objects created on my database and I need to delete some of the repeating attributes related to them.
The query I'm trying to run is:
UPDATE gemp1_product objects REMOVE ingredients[1] WHERE (r_object_id = '08015abd8002cd68')
But all I get is the folloing error message:
Error querying databse.
[DM_QUERY_E_UPDATE_INDEX]error: "UPDATE: Unable to REMOVE tghe attribute ingredients at index 1."
[DM_OBJECT_W_DELETE_ATTR_POSITION_ERROR]warning: "attempt to delete
non-existent attribute 88"
Object 08015abd8002cd68 exists and I can see it on the database. Queries like SELECT and DELETE work fine but I do not want to delete the whole object.
There is no easy way to do this. The reason is that repeating attributes are ordered, to enable multiple repeating attributes to be synchronized for a given object.
Either
set the attribute value to be empty for the given position, and change your code to discard empty attributes, or
use multiple DQL statements to shuffle the order so that the last one becomes empty, or
change your data model, e.g. use a single attribute as a property bag with pre-defined delimiters.
Details (1)
UPDATE gemp1_product OBJECTS SET ingredients[1] = '' WHERE ...
Details (2)
For each index; first find the value of index+1:
SELECT ingredients
FROM gemp1_product
WHERE (i_position*-1)-1 = <index+1>
ENABLE (ROW_BASED)
Use the value in a new query:
UPDATE gemp1_product OBJECTS SET ingredients[1] = '<value_from_above>' WHERE ...
It should also be possible to do this by nesting DQL somehow, but it might not be worth the effort.
Something is either wrong with your query or with your repository. I think you are mistyping your attribute name or using wrong index in your UPDATE query.
If you google for DM_OBJECT_W_DELETE_ATTR_POSITION_ERROR you'll see on this link a bit more detailed explanation:
CAUSE: Program executed a DeleteAttr operation that specified an non-existent attribute position (either a negative number or a number larger than the number of attributes in the object).
From this you could guess that type isn't in consistent state, or that you are trying to remove too big index of your repeating attribute, etc. Did you checked your repository with Consistency checker Job and other similar Jobs?
As of for the removing of repeating property (sttribute) value with DQL query, this is unachievable with single query since you need to specify index position which you don't know at first. But writing a simple script or doing it manually if it's not big amount of values to delete is the way you want to go.
I'm creating a caching system to take data from an SQLite database table using a sorted/filtered query and display it. The tables I'm pulling from can be potentially very large and, of course, I need to minimize impact on memory by only retaining a maximum number of rows in memory at any given time. This is easily done by using LIMIT and OFFSET to load only the records I need and update the cache as needed. Implementing this is trivial. The problem I'm having is determining where the insertion index is for a new record inserted into a particular query so I can update my UI appropriately. Is there an easy way to do this? So far the ideas I've had are:
Dump the entire cache, re-count the Query results (there's no guarantee the new row will be included), refresh the cache and refresh the entire UI. I hope it's obvious why that's not really desirable.
Use my own algorithm to determine whether the new row is included in the current query, if it is included in the current cached results and at what index it should be inserted into if it's within the current cached scope. The biggest downfall of this approach is it's complexity and the risk that my own sorting/filtering algorithm won't match SQLite's.
Of course, what I want is to be able to ask SQLite: Given 'Query A' what is the index of 'Row B', without loading the entire query results. However, so far I haven't been able to find a way to do this.
I don't think it matters but this is all occurring on an iOS device, using the objective-c programming language.
More Info
The Query and subsequent cache is based off of user input. Essentially the user can re-sort and filter (or search) to alter the results they're seeing. My reticence in simply recreating the cache on insertions (and edits, actually) is to provide a 'smoother' UI experience.
I should point out that I'm leaning toward option "2" at the moment. I played around with creating my own caching/indexing system by loading all the records in a table and performing the sort/filter in memory using my own algorithms. So much of the code needed to determine whether and/or where a particular record is in the cache is already there, so I'm slightly predisposed to use it. The danger lies in having a cache that doesn't match the underlying query. If I include a record in the cache that the query wouldn't return, I'll be in trouble and probably crash.
You don't need record numbers.
Save the values of the ordered field in the first and last records of the LIMITed query result.
Then you can use these to check whether the new record falls into this range.
In other words, assuming that you order by the Name field, and that the original query was this:
SELECT Name, ...
FROM mytab
WHERE some_conditions
ORDER BY Name
LIMIT x OFFSET y
then try to get at the new record with a similar query:
SELECT 1
FROM mytab
WHERE some_conditions
AND PrimaryKey = LastInsertedValue
AND Name BETWEEN CachedMin AND CachedMax
Similarly, to find out before (or after) which record the new record was inserted, start directly after the inserted record and use a limit of one, like this:
SELECT Name
FROM mytab
WHERE some_conditions
AND Name > MyInsertedName
AND Name BETWEEN CachedMin AND CachedMax
ORDER BY Name
LIMIT 1
This doesn't give you a number; you still have to check where the returned Name is in your cache.
Typically you'd expect a cache to be invalidated if there were underlying data changes. I think dropping it and starting over will be your simplest, maintainable solution. I would recommend it unless you have a very good reason.
You could write another query that just returned the row count (example below) to see if your cache should be invalidated. That would save recreating the cache when it did not change.
SELECT name,address FROM people WHERE area_code=970;
SELECT COUNT(rowid) FROM people WHERE area_code=970;
The information you'd need from sqlite to know when your cache was invalidated would require some rather intimate knowledge of how the query and/or index was working. I would say that is fairly high coupling.
Otherwise, you'd want to know where it was inserted with regards to the sorting. You would probably key each page on the sorted field. Delete anything greater than the insert/delete field. Any time you change the sorting you'd drop everything.
Something like the below would be a start if you were using C++. I realize you aren't doing C++, but hopefully it is evident as to what I'm trying to do.
struct Person {
std::string name;
std::string addr;
};
struct Page {
std::string key;
std::vector<Person> persons;
struct Less {
bool operator()(const Page &lhs, const Page &rhs) const {
return lhs.key.compare(rhs.key) < 0;
}
};
};
typedef std::set<Page, Page::Less> pages_t;
pages_t pages;
void insert(const Person &person) {
if (sql_insert(person)) {
pages_t::iterator drop_cache_start = pages.lower_bound(person);
//... drop this page and everything after it
}
}
You'd have to do some wrangling to get different datatypes of key to work nicely, but its possible.
Theoretically you could just leave the pages out of it and only use the objects themselves. The database would no longer "own" the data though. If you only fill pages from the database, then you'll have less data consistency worries.
This may be a bit off topic, you aren't re-implementing views are you? It doesn't cache per se, but it isn't clear if that is a requirement of your project.
The solution I came up with is not exactly simple, but it's currently working well. I realized that the index of a record in a Query Statement is also the Count of all it's previous records. What I needed to do was 'convert' all the ORDER statements in the query to a series of WHERE statements that would return only the preceding records and take a count of those records. It's trickier than it sounds (or maybe not...it sounds tricky). The biggest issue I had was making sure the query was, in fact, sorted in a way I could predict. This meant I needed to have an order column in the Order Parameters that was based off of a column with unique values. So, whenever a user sorts on a column, I append to the statement another order parameter on a unique column (I used a "Modified Date Stamp") to break ties.
Creating the WHERE portion of the statement requires more than just tacking on a bunch of ANDs. It's easier to demonstrate. Say you have 3 Order columns: "LastName" ASC, "FirstName" DESC, and "Modified Stamp" ASC (the tie breaker). The WHERE statement would have to look something like this ('?' = record value):
WHERE
"LastName" < ? OR
("LastName" = ? AND "FirstName" > ?) OR
("LastName" = ? AND "FirstName" = ? AND "Modified Stamp" < ?)
Each set of WHERE parameters grouped together by parenthesis are tie breakers. If, in fact, the record values of "LastName" are equal, we must then look at "FirstName", and finally "Modified Stamp". Obviously, this statement can get really long if you're sorting by a bunch of order parameters.
There's still one problem with the above solution. Mathematical operations on NULL values always return false, and yet when you sort SQLite sorts NULL values first. Therefore, in order to deal with NULL values appropriately you've gotta add another layer of complication. First, all mathematical equality operations, =, must be replace by IS. Second, all < operations must be nested with an OR IS NULL to include NULL values appropriately on the < operator. This turns the above operation into:
WHERE
("LastName" < ? OR "LastName" IS NULL) OR
("LastName" IS ? AND "FirstName" > ?) OR
("LastName" IS ? AND "FirstName" IS ? AND ("Modified Stamp" < ? OR "Modified Stamp" IS NULL))
I then take a count of the RowID using the above WHERE parameter.
It turned out easy enough for me to do mostly because I had already constructed a set of objects to represent various aspects of my SQL Statement which could be assembled to generate the statement. I can't even imagine trying to manipulate a SQL statement like this any other way.
So far, I've tested using this on several iOS devices with up to 10,000 records in a table and I've had no noticeable performance issues. Of course, it's designed for single record edits/insertions so I don't really need it to be super fast/efficient.