How can I use merge with sepecify row in H2? Any answers are welcome and I appreciate
I mean how to merge with the values passed from outside.
Example:
I wanna merge the row with name = "john" and id = "1" in table customer.
what the statement in this case
I'm not sure if you really mean the MERGE statement, but the documentation is on the web site.
Related
I have this situation. Starting from a table, I have to check all the records that match a key. If records are found, I have to check another table using a key from the first table and so on, more on less on five levels. There is a way to do this in a recursive way, or I have to write all the code "by hand"? The language I am using is Visual Fox Pro. If this is is not possible, is it al least possible to use recursion to popolate a treeview?
You can set a relation between tables. For example:
USE table_1.dbf IN 0 SHARED
USE table_2.dbf IN 0 SHARED
SET ORDER TO TAG key_field OF table_2.cdx IN table_2
SET RELATION TO key_field INTO table_2 ADDITIVE IN table_1
First two commands open table_1 and table_2. Then you have to set the order/index of table_2. If you don't have an index for the key field then this will not work. The final command sets the relation between the two tables on the key field.
From here you can browse both tables and table_2's records will be filtered based on table_1's key field. Hope this helps.
If the tables have similar structure or you only need to look at a few fields, you could write a recursive routine that receives the name of the table, the key to check, and perhaps the fields you need to check as parameters. The tricky part, I guess, is knowing what to pass down to the next call.
I don't think I can offer any more advice without at least seeing some table structures.
Sorry for answering so late, but the problem was of course that the recursion wasn't a viable solution since I had to search inside multiple tables. So I resolved by doing a simple 2-Level search in the tables that I needed.
Thank you very much for the help, and sorry again for answering so late.
I have an assignment where I have two tables. Both of these two tables have multiple records that can be grouped by a certain ID creating record sets within those two tables
Those record sets can have various number of records. The trick is I have to compare those two tables and compare them by those record sets. If one record set ordered by update date (one of the record fields) doesn't find an identical record set in another table, I have to output that record set
What is the best way to do it? How do I compare two different tables by record groups/record sets/record blocks?
Should I use sub-query factoring? Should I temporary tables? Should I use something else?
Thank you very much for your generous responses and please let me know if I made my question unclear
i guess you just need a minus query to show the differences.
If you use Toad there is a specific function. Or you can use the minus operator or read this other post link
I am looking for a way to have a query that returns a tuple first sorted by a column, then grouped by another (in that order). Simply .sort_by().group_by() didn't appear to work. Now I tried the following, which made the return value go wrong (I just got the orm object, not the initial tuple), but read for yourself in detail:
Base scenario:
There is a query which queries for test orm objects linked from the test3 table through foreign keys.
This query also returns a column named linked that either contains true or false. It is originally ungrouped.
my_query = session.query(test_orm_object)
... lots of stuff like joining various things ...
add_column(..condition that either puts 'true' or 'false' into the column..)
So the original return value is a tuple (the orm object, and additionally the true/false column).
Now this query should be grouped for the test orm objects (so the test.id column), but before that, sorted by the linked column so entries with true are preferred during the grouping.
Assuming the current unsorted, ungrouped query is stored in my_query, my approach to achieve this was this:
# Get a sorted subquery
tmpquery = my_query.order_by(desc('linked')).subquery()
# Read the column out of the sub query
my_query = session.query(tmpquery).add_columns(getattr(tmpquery.c,'linked').label('linked'))
my_query = my_query.group_by(getattr(tmpquery.c, 'id')) # Group objects
The resulting SQL query when running this is (it looks fine to me btw - the subquery 'anon_1' is inside itself properly sorted, then fetched and its id aswell as the 'linked' column is extracted (amongst a few other columns SQLAlchemy wants to have apparently), and the result is properly grouped):
SELECT anon_1.id AS anon_1_id, anon_1.name AS anon_1_name, anon_1.fk_test3 AS anon_1_fk_test3, anon_1.linked AS anon_1_linked, anon_1.linked AS linked
FROM (
SELECT test.id AS id, test.name AS name, test.fk_test3 AS fk_test3, CASE WHEN (anon_2.id = 87799534) THEN 'true' ELSE 'false' END AS linked
FROM test LEFT OUTER JOIN (SELECT test3.id AS id, test3.fk_testvalue AS fk_testvalue
FROM test3)
AS anon_2 ON anon_2.fk_testvalue = test.id ORDER BY linked DESC
)
AS anon_1 GROUP BY anon_1.id
I tested it in phpmyadmin, where it gave me, as expected, the id column (for the orm object id), then the additional columns SQL_Alchemy seems to want there, and the linked column. So far, so good.
Now my expected return values would be, as they were from the original unsorted, ungrouped query:
A tuple: 'test' orm object (anon_1.id column), 'true'/'false' value (linked column)
The actual return value of the new sorted/grouped query is however (the original query DOES indeed return a touple before the code above is applied):
'test' orm object only
Why is that so and how can I fix it?
Excuse me if that approach turns out to be somewhat flawed.
What I actually want is, have the original query simply sorted, then grouped without touching the return values. As you can see above, my attempt was to 'restore' the additional return value again, but that didn't work. What should I do instead, if this approach is fundamentally wrong?
Explanation for the subquery use:
The point of the whole subquery is to force SQLAlchemy to execute this query separately as a first step.
I want to order the results first, and then group the ordered results. That seems to be hard to do properly in one step (when trying manually with SQL I had issues combining order and group by in one step as I wanted).
Therefore I don't simply order, group, but I order first, then subquery it to enforce that the order step is actually completed first, and then I group it.
Judging from manual PHPMyAdmin tests with the generated SQL, this seems to work fine. The actual problem is that the original query (which is now wrapped as the subquery you were confused about) had an added column, and now by wrapping it up as a subquery, that column is gone from the overall result. And my attempt to readd it to the outer wrapping failed.
It would be much better if you provided examples. I don't know if these columns are in separate tables or what not. Just looking at your first paragraph, I would do something like this:
a = session.query(Table1, Table2.column).\
join(Table2, Table1.foreign_key == Table2.id).\
filter(...).group_by(Table2.id).order_by(Table1.property.desc()).all()
I don't know exactly what you're trying to do since I need to look at your actual model, but it should look something like this with maybe the tables/objs flipped around or more filters.
Say i have something like this:
somerecord SOMETABLE%ROWTYPE;
Is it possible to access the fields of somerecord with out knowing the fields names?
Something like somerecord[i] such that the order of fields would be the same as the column order in the table?
I have seen a few examples using dynamic sql but i was wondering if there is a cleaner way of doing this.
What i am trying to do is generate/get the DML (insert query) for a specific row in my table but i havent been able to find anything on this.
If there is another way of doing this i'd be happy to use but would also be very curious in knowing how to do the former part of this question - it's more versatile.
Thanks
This doesn't exactly answer the question you asked, but might get you the result you want...
You can query the USER_TAB_COLUMNS view (or the other similar *_TAB_COLUMN views) to get information like the column name (COLUMN_NAME), position (COLUMN_ID), and data type (DATA_TYPE) on the columns in a table (or a view) that you might use to generate DML.
You would still need to use dynamic SQL to execute the generated DML (or at least generate static SQL separately).
However, this approach won't work for identifying the columns in an arbitrary query (unless you create a view of it). If you need that, you might need to resort to DBMS_SQL (or other tools).
Hope this helps.
As far as I know there is no clean way of referencing record fields by their index.
However, if you have a lot of different kinds of updates of the same table each with its own column set to update, you might want to avoid dynamic sql and look in the direction of statically populating your record with values, and then issuing update someTable set row = someTableRecord where someTable.id = someTableRecord.id;.
This approach has it's own drawbacks, like, issuing an update to every, even unchanged column, and thus creating additional redo log data, but I believe it should be considered.
Anyone ever see how fogbugz sorts their tables? When you click to sort the column, they actually break the table up into many small tables that have each category of info.
Wondering if anyone knows how they do this?
Looking to implement this feature.
If you take a look through the cases page, and sort you can see what I mean.
Any help would be AWESOME!
Still Haven't figured this one out.
EDIT: #Peter, I don't want to postback and recreate a table every time the header title is clicked for a sort. I also want to know if their is a generic solution for this. If I click on the header to sort, by the way of javascript, it seperates the "one" table into many and I want to know if their is any generic solution for this because its just a MUCH better way of viewing a sorted Table.
EDIT: I do need a javascript sorter, but if you look right down at the implementation of fogbugz, it produces a different result...
Yup, Rich got it (I coded this feature into FogBugz a long while back).
If you have to do this on the client you have no choice but to sort the data, iterate through it generating table row after table row, and every time you hit a new sort value you create a new thead w/ the appropriate information.
To be honest it would be a pretty cool modification to this jQuery plugin: http://tablesorter.com/docs/ and you'd be able to leverage a lot of their work. If you're going to put in the time and create a general solution, might as well make it accessible to the community.
Without knowing specifically how Fog Creek accomplishes this, the way that I would do it is to output a table header, then iterate through the list, outputting a footer and a new header each time the group value changed.
Not sure what answer do you expect. SQL query for this would simply use ordering on selected column, and UI would start new table each time this value changes.
Here is screenshot of FogBugz with this sorting, after clicking on Priority column.
http://img297.imageshack.us/img297/6974/76755363ee3.png
Of course, starting new table doesn't make sense for every column (title, case #).
Edit: If I understand correctly, you're looking for a way how to do this in a browser without loading new page. If this is the case, I would suggest at least some server-side support, which would return your data in correct order, and properly structured for subtables (in xml/json/whatever you use). Your javascript will use this data to recreate tables. I am sure others with more web-ui experience will provide you with better answers.
I've used the Sortable Tables script from Kryogenix with some good results.
I don't know if it is relevant, but we store the results of a query in a temporary table in SQL, and then reference current-row-less-one to see if a Category has changed, and indicate this in the resulset.
In some instances we "indicate" this with a column containing
<tr><td colspan=999>Category Heading</td></tr>
so that the web page can just "inject" that into the table it is building.
SELECT Col1, Col2, ...,
[CATEGORY] = CASE WHEN T1.CategoryCol <> COALESCE(T2.CategoryCol, '')
THEN '<tr><td colspan=999>' + T1.CategoryCol + '</td></tr>'
ELSE ''
END
FROM #MyTempTable AS T1
LEFT OUTER JOIN #MyTempTable AS T2
ON T2.ID = T1.ID - 1