How can I select only distinct records, from relational table, when using with() operator in Yii?
I'm getting my models (records) like that:
$probe = Probes::model()->with(array
(
'user',
'results',
'results.answer',
'survey',
'survey.questions',
'survey.questions.question',
'survey.questions.question.answers',
'manager'
))->findByPk($id);
I want to make sure, that survey.questions relation returns only distinct records. But it seems, that I don't see any way to achieve this (or I'm blind / not educated enough).
When giving relational table name / alias as array:
'results.question'=>array('alias'=>'results_question'),
the distinct key is not among those, that can be used in such array (as modifier).
I tried very ugly, bumpy way of changing select from default * to DISTINCT *:
'survey.questions'=>array('select'=>'distinct'),
But this has (of course?) failed:
Active record "SurveysQuestions" is trying to select an invalid column "distinct". Note, the column must exist in the table or be an expression with alias.
How can I achieve this (seemed so obvious and easy), if it is possible at all this way (using with())? If not, then -- please, advice how to get distinct records in relational table any way (other than manually filtering results using foreach, what I'm doing right now, and what is ugly).
You could set CDbCriteria::distinct to true:
'survey.questions'=>array('distinct'=>true),
Related
I'm running Apex 19.2 and I would like to create a classical or interactive report based on dynamic query.
The query I'm using is not known at design time. It depends on an page item value.
-- So I have a function that generates the SQL as follows
GetSQLQuery(:P1_MyItem);
This function may return something like
select Field1 from Table1
or
Select field1,field2 from Table1 inner join Table2 on ...
So it's not a sql query always with the same number of columns. It's completely variable.
I tried using PL/SQL function Body returning SQL Query but it seems like Apex needs to parse the query at design time.
Has anyone an idea how to solve that please ?
Cheers,
Thanks.
Enable the Use Generic Column Names option, as Koen said.
Then set Generic Column Count to the upper bound of the number of columns the query might return.
If you need dynamic column headers too, go to the region attributes and set Type (under Heading) to the appropriate value. PL/SQL Function Body is the most flexible and powerful option, but it's also the most work. Just make sure you return the correct number of headings as per the query.
I have a big calculation that joins together about 10 tables and calculates some values from the result. I want to write a function that allows me to replace one of the tables that are joined (lets call it Table A) with a table (type) I give as an input parameter.
I have defined row and table types for table A like
create or replace TYPE t_tableA_row AS OBJECT(*All Columns of Table A*);
create or replace TYPE t_tableA_table as TABLE OF t_tableA_row;
And the same for the types of the calculation I need as an output of the function.
My functions looks like this
create or replace FUNCTION calculation_VarInput (varTableA t_tableA_table)
RETURN t_calculationResult_table AS
result_ t_calculationResult_table;
BEGIN
SELECT t_calculationResult_row (*All Columns of Calculation Result*)
BULK COLLECT INTO result_
FROM (*The calculation*)
RETURN result_;
END;
If I test this function with the normal calculation that just uses Table A(ignoring the input parameter), it works fine and takes about 3 Second. However, if I replace Table A with varTableA (the input parameter that is a table type of Table A), the calculation takes so long I have never seen it finish.
When I use table A for the calculation it looks like this
/*Inside the calculation*/
*a bunch tables being joined*
JOIN TableA A On A.Value = B.SomeOtherValue
JOIN *some other tables*
When I use varTableA its
/*Inside the calculation*/
*a bunch tables being joined*
JOIN TABLE(varTableA ) A On A.Value = B.SomeOtherValue
JOIN *some other tables*
Sorry for not posting the exact code but the calculation is huge and would really bloat this post.
Any ideas why using the table type when joining makes the calculation so much slower when compared to using the actual table?
Your function encapsulates some selection logic in a function and so hides information from the optimizer. This may lead the optimizer to make bad or inefficient decisions.
Oracle has gathered statistics for TableA so the optimizer knows how many rows it has, what columns are indexed and so on. Consequently it can figure out the best access path for the table. It has no stats for TABLE(varTableA ) so it assumes it will return 8192 (i.e. 8k) rows. This could change the execution plan if say the original TableA returned 8 rows. Or 80000. You can check this easily enough by running EXPLAIN PLAN for both versions of query.
If that is the problem add a /*+ cardinality */ to the query which accurately reflects the number of rows in the function's result set. The hint (hint, not function) tells the optimizer the number of rows it should use in its calculation.
I don't want to actually change the values in my tables permanently, I just want to know what the calculation result would be if some values were different.
Why not use a view instead? A simple view which selects from TableA and applies the required modifications in its projection. Of course I know nothing about your data and how you want to manipulate it, so this may be impractical for all sorts of reasons. But it's where I would start.
I need to work with a SQL result set in order to do some processing for each column (medians, standard deviations, several control statements included)
The SQL is dynamic so I don't know the number of columns, rows.
First I tried to use temporary tables, views, etc to store the results, however I did not manage to overcome the 30 character limit of Oracle columns when using the below sql:
create table (or view or global temporary table) as select * from (
SELECT
DMTTBF_MAT_MATURATO_BILL_POS.MAT_V_COD_ANNOMESE,
SUM(DMTTBF_MAT_MATURATO_BILL_POS.MAT_N_NUM_EVENTI_CHZ +DMTTBF_MAT_MATURATO_BILL_POS. MAT_N_NUM_EVENTI) <-- exceeds the 30 character limit
FROM DMTTBF_MAT_MATURATO_BILL_POS
WHERE DMTTBF_MAT_MATURATO_BILL_POS.MAT_V_COD_ANNOMESE >= '201301'
GROUP BY DMTTBF_MAT_MATURATO_BILL_POS.MAT_V_COD_ANNOMESE
)
Second choice was to use some PL/SQL types to store the entire table information, so I could call it like in other programming languages (e.g. a matrix result[i][j]) but I could not find anything similar.
Third variant, using files for reading and writing: i did not try it yet; i'm still expecting a more elegant pl/sql solution
It's possible that I have the wrong approach here so any advice is more than welcome.
UPDATE: Modifying the input SQL is not an option. The program has to accept any select statement.
Note that you can alias both tables and fields. Using a table alias keeps references to it from producing walls of text in the query. Using one for a field gives it a new name in the output.
SELECT A.LONG_FIELD_NAME_HERE AS SHORTNAME
FROM REALLY_LONG_TABLE_NAME_HERE A
The auto naming adds _1 and _2 etc to differentiate the same column name coming from different table references. This often puts a field already borderline over the limit. Giving the fields names yourself bypasses this.
You can put the alias also in dynamic SQL:
sqlstr := 'create table (or view or global temporary table) as select * from (
SELECT
DMTTBF_MAT_MATURATO_BILL_POS.MAT_V_COD_ANNOMESE,
SUM(DMTTBF_MAT_MATURATO_BILL_POS.MAT_N_NUM_EVENTI_CHZ + DMTTBF_MAT_MATURATO_BILL_POS.MAT_N_NUM_EVENTI) AS '||SUBSTR('SUM(DMTTBF_MAT_MATURATO_BILL_POS.MAT_N_NUM_EVENTI_CHZ +DMTTBF_MAT_MATURATO_BILL_POS.MAT_N_NUM_EVENTI)', 1, 30)
||' FROM DMTTBF_MAT_MATURATO_BILL_POS
WHERE DMTTBF_MAT_MATURATO_BILL_POS.MAT_V_COD_ANNOMESE >= ''201301''
GROUP BY DMTTBF_MAT_MATURATO_BILL_POS.MAT_V_COD_ANNOMESE
)'
Maybe, this question is a little stupid, but I'm confused.
How to group records by specified column ? :)
Item.group(:category_id)
does't works...
It says:
ActiveRecord::StatementInvalid: PGError: ERROR: column "items.id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: SELECT "items".* FROM "items" GROUP BY category_id
What kind of aggregate function should i use?
Please, could you provide a simple example.
You will have to define, how to group values that share the same category_id. Concatenate them? Calculate a sum?
To create comma-separated lists of values your statement could look like this:
SELECT category_id
,string_agg(col1, ', ') AS col1_list
,string_agg(col2, ', ') AS col2_list
FROM items
GROUP BY category_id
You need Postgres 9.0 or later for string_agg(col1, ', ').
In older versions you can substitute with array_to_string(array_agg(col1), ', '). More aggregate functions here.
To aggregate values in PostgreSQL is the clearly superior approach as opposed to aggregating values in the client. Postgres is very fast at this and it reduces (network) traffic.
You can use sum, avg, count or any other aggregate function. More on this topic you can find here.
But it seems that you don't really need to use SQL grouping.
Try to fetch all records and then use Array#collect function to group Items by category_id
Grouping in SQL means that the server groups one or more records from the database table into one resulting row. So, if you for example group by category_id, you might have several records matching the given category, so you can't expect the database to return all columns from the table (that's what SELECT * actually does).
Instead, when you use GROUP BY, you can SELECT only:
columns you have grouped by, and/or
aggregate functions which are performed on all the records belonging to a resulting group
Depending on what you exactly need, modify your .select accordingly.
<-------PeopleCode------>
Hi,
I have a SQL query that i have tried executing using both SQLEXEC and SQL.fetch() but the problem is, when I am passing the values to parameters (:1,:2...) it does not return a row but when I hardcode the values in the where clause of the query itself, it retrieves the correct value.
Can anybody help?
My query looks similar to the following sample query :
Select * from PS_rec1 where emplid=:1 and plan_type=:2
it returns no data till i hardcode the values.
I have checked the values at the back end and some data is there to be fetched. Moreover, the same query retrieves data when ran in TOAD.
Have you tried outputting your binds to a log file just before you use them in your SQL statement?
If the binds aren't working, but literals are, then perhaps your binds don't contain the values that you expect them to.
You could also try explicitly setting the binds to the values that you're expecting just before the SQL statement. This will prove that the way you're passing in the binds is working correctly.
It required another update to the same record to get the values fetched in SQL exec.
M not sure what was the problem but i guess it might be that the previous update did not write the changes to the db even after an explicit commit.
Ok, you need to put your exact SQLExec statement in the question.
But, do you really have "Select * ..." in a SQLExec? How many columns are in your table? Since you mention the where clause, is your statement
SQLExec("select * from PS_rec where emplid=:1 and plan_type=:2", &var1, &var2, &vartocontainthewholerow);
Which will work in a SQL tool (toad) but probably does not work in AE or any type of Peoplecode program.
Now if your table has three columns, should you not have something like this:
SQLExec("select emplid, plan_type, column3 from PS_rec where emplid = :1 and plan_type=:2", &emplidIn, &plan_typeIn, &emplidOut, &plan_typeOut, &column3Out);
Notice that with three columns in the table that emplid and plan_type are two of them, you need to list all the columns you want, not asterisks '*'. Kind of silly to select the emplid and plan_type though.