In my Ruby on Rails app I'm using blazer(https://github.com/ankane/blazer) and I have the following sql query:
SELECT *
FROM survey_results sr
LEFT JOIN clients c ON c.id = sr.client_id
WHERE sr.client_id = {client_id}
This query works really well. But I need to add conditional logic to check if client_id variable is present. If yes then I filter by this variable, if not then I not launching this where clause. How can I do it in PostgreSQL?
Check if its null OR your condition like this:
WHERE {client_id} IS NULL OR sr.client_id = {client_id}
The WHERE clause evaluate as follow: If the variable is empty, then the WHERE clause evaluate to true, and therefore - no filter. If not, it continue to the next condition of the OR
If anyone faced with the psql operator does not exist: bigint = bytea issue, here is my workaround:
WHERE ({client_id} < 0 AND sr.client_id > {client_id}) OR sr.client_id = {client_id}
Please consider that, client_id generally cannot be negative so you can use that information for eleminating the operation cast issue.
My solution:
I use spring data jpa, native query.
Here is my repository interface signature.
#Query(... where (case when 0 in :itemIds then true else i.id in :itemIds end) ...)
List<Item> getItems(#Param("itemIds) List<Long> itemIds)
Prior calling this method, I check if itemIds is null. If yes, I set value to 0L:
if(itemIds == null) {
itemIds = new ArrayList<Long>();
itemIds.add(0L);
}
itemRepo.getItems(itemIds);
My IDs starts from 1 so there is no case when ID = 0.
Related
I am looking to pass declared variables to build my string. I think I want to set my variable via a case expression but I have not done this before. Here is what I have done thus far.
DECLARE #stu_conv AS VARCHAR(5)
-- I think I need a select here.
set #stu_conv = CASE WHEN ITMMASTER.STU_0 ='KG' THEN'2.2'END
SELECT
YPRIMAT.YCROPYR_0
,ITMMASTER.TCLCOD_0
,SPRICLIST.DCGVAL_3
,ITMMASTER.TSICOD_2
,ITMMASTER.ACCCOD_0
,(BASPRI_0*#stu_conv) AS ImportstringAS Importstring
FROM LIVE.YPRIMAT
INNER JOIN LIVE.ITMMASTER ON YPRIMAT.ITMREF_0 = ITMMASTER.ITMREF_0
LEFT OUTER JOIN LIVE.SPRICLIST ON ITMMASTER.TCLCOD_0 = SPRICLIST.PLICRI1_0
WHERE SPRICLIST.PLICRD_0 = 'SPL000020'
I don't see the point for using a variable here, and trying to set it outside the query does not make sense, since you most likely want the value to reset for each row.
I would suggest moving the case expression into the query, as follows:
select
y.ycropyr_0,
i.tclcod_0,
s.dcgval_3,
i.tsicod_2,
i.acccod_0,
baspri_0 * case when i.stu_0 = 'KG' then 2.2 else 1 end as importstringas importstring
from live.yprimat y
inner join live.itmmaster i on y.itmref_0 = i.itmref_0
left outer join live.spriclist s on i.tclcod_0 = s.plicri1_0
where s.plicrd_0 = 'SPL000020'
I assumed that you want a value of 1 when stu_0 is not 'KG', but you can change this as needed.
Side note:
I modified your query to use table aliases. This makes the query shorter to write and somehow easier to read
you would need to prefix column baspri_0 with the table it belongs to (as your query is, it is not possible to tell)
I'm not sure why you're declaring a string and then multiplying it, but I would just inline the case (and add a default case?):
,(BASPRI_0 * CASE
WHEN ITMMASTER.STU_0 ='KG'
THEN 2.2
ELSE ???
END) AS Importstring
I am trying to update sum of particular amount from one table as a value in another table, but getting problem when the particular id does not exist in another table :
the hql i have looks like beow:
var session = SessionManager.GetCurrentSession();
var queryString = string.Empty;
queryString += #"update CLiner cl set cl.UnbilledDue =
(select sum(cu.UnbilledAmount) as UnbilledAmount from CUnbilled cu
where cu.AccountNo = cl.AccountNo and cu.FileDate = :fileDate)
where cl.FileDate = :fileDate ";
var query = session.CreateQuery(queryString);
query.SetDateTime("fileDate", new DateTime(2014, 10, 7));
query.ExecuteUpdate();
but its giving exception when the particular account no does not exist in child table and the sum is returned as zero.
i tried changing the subquery select to
select isnull(sum(cu.UnbilledAmount),0) as UnbilledAmount
which as expected is not supported by nhibernate hql. so there a way i can convert null to zero in hql select statement...
Try this:
coalesce(sum(cu.UnbilledAccount), 0)
Reason:
Normally when you wirte a SQL query to prevent NULL you must apply an ISNULL function over the SELECT, in this way:
ISNULL(SELECT sum(...., 0) or COALESCE(SELECT sum(...., 0) (return the same result but COALESCE can applied with more parameter, ISNULL has only two parameters)
but in HQL isn't possible, so you can use COALESCE function to prevent that behaviour.
I want to change the query to return multiply values in extra_fields, how can I change the regex? Also I don't understand what extra_fields is - is it a field? If so why it is not called with the table prefix like i.extra_fields?
SELECT i.*,
CASE WHEN i.modified = 0 THEN i.created ELSE i.modified END AS lastChanged,
c.name AS categoryname,
c.id AS categoryid,
c.alias AS categoryalias,
c.params AS categoryparams
FROM #__k2_items AS i
LEFT JOIN #__k2_categories AS c ON c.id = i.catid
WHERE i.published = 1
AND i.access IN(1,1)
AND i.trash = 0
AND c.published = 1
AND c.access IN(1,1)
AND c.trash = 0
AND (i.publish_up = '0000-00-00 00:00:00'
OR i.publish_up <= '2013-06-12 22:45:19'
)
AND (i.publish_down = '0000-00-00 00:00:00'
OR i.publish_down >= '2013-06-12 22:45:19'
)
AND extra_fields REGEXP BINARY '(.*{"id":"2","value":\["[^\"]*1[^\"]*","[^\"]*2[^\"]*","[^\"]*3[^\"]*"\]}.*)'
ORDER BY i.id DESC
The extra_fields is a column of the #__k2_items table. The table qualifier can be omitted, because it is not ambiguous in this query. The column is JSON encoded. That is a serialization format used to store information which is not searchable by design. Applying a RegExp may work one day, but fail another day, since there is no guarantee for id preceeding value (as in your example).
The right way
The right way to filter this is to ignore the extra_fields condition in the SQL query an evaluate in the resultset instead. Example:
$rows = $db->loadObjectList('id');
foreach ($rows as $id => $row) {
$extra_fields = json_decode($row->extra_fields);
if ($extra_fields->id != 2) {
unset($rows[$id]);
}
}
The short way
If you can't change the database layout (which is true for extensions you want to keep updateable), you must split the condition into two, because there is no guarantee for a certain order of the subfields. For some reason, one day value may occur before id. So change your query to
...
AND extra_fields LIKE '%"id":"2"%'
AND extra_fields REGEXP BINARY '"value":\[("[^\"]*[123][^\"]*",?)+\]'
Prepare an intermediate table to hold the contents of extra_fields. Each extra_fields field will be converted into a series of records. Then do a join.
Create a trigger and cronjob to keep the temp table in sync.
Another way is to write UDF in Perl that will decode the field, but AFAIK it is not indexable in mysql.
Using an external search engine is out of scope.
Ok, i didnt want to change the db strucure, i gost some help and changed the regex intoAND extra_fields REGEXP BINARY '(.*{"id":"2","value":\[("[^\"]*[123][^\"]*",?)+\]}.*)'
and i got the right resaults
Thanks
I'm trying to get data from Cassandra with this query:
$cf=new ColumnFamily($data->cp,'ips');
$index[]=CassandraUtil::create_index_expression('c',1,'EQ');
$index[]=CassandraUtil::create_index_expression('begin_ip',1599147740,'GTE');
$index[]=CassandraUtil::create_index_expression('end_ip',1599147740,'LTE');
$index_clause = CassandraUtil::create_index_clause($index);
$rows=$cf->get_indexed_slices($index_clause);
foreach($rows AS $key=>$row)
{
$result[]=$row;
}
var_dump($result);
But the result is null.
I'm definitely sure that there is a row in cf ips which absolutely answers this query.
Validation class for all columns is IntegerType.
In cassandra-cli the equal query:
get ips where c = int('1') and
begin_ip <= int('1599147740') and
end_ip >= int('1599147740');
also gets null.
What am I doing wrong?
First, have you created an index on the 'c' column?
Second, you'll need to use 'cassandra_IndexOperator::EQ' and similar for the expression operator instead of a string.
I have a table with a 'Wav' column that is of type 'VARBINARY(max)' (storing a wav file) and would like to be able to check if there is a wav from Linq to SQL.
My first approach was to do the following in Linq:
var result = from row in dc.Table
select new { NoWav = row.Wav != null };
The problem with the code above is it will retreive all the binary content to RAM, and this isn't good (slow and memory hungry).
Any idea how to have Linq query to translate into something like bellow in SQL?
SELECT (CASE WHEN Wav IS NULL THEN 1 ELSE 0 END) As NoWav FROM [Update]
Thanks for all the replies. They all make sense. Indeed, Linq should translate the != null correctly, but it didn't seem to effectively do it: running my code was very slow, so somehow my only explaination is that it got the binary data transfered over to the RAM.... but maybe I'm wrong.
I think I found a work around anyway somewhere else on stackoverflow: Create a computed column on a datetime
I ran the following query against my table:
ALTER TABLE [Table]
ADD WavIsNull AS (CASE WHEN [Wav] IS NULL Then (1) ELSE (0) END)
Now I'll update my DBML to reflect that computed column and see how it goes.
Are you sure that this code will retrieve the data to RAM?
I did some testing using LINQPad and the generated SQL was optimized as you suggest:
from c in Categories
select new
{
Description = c.Description != null
}
SELECT
(CASE
WHEN [t0].[description] IS NOT NULL THEN 1
ELSE 0
END) AS [Description]
FROM [Category] AS [t0]
What about this query:
var result = from row in dc.Table where row.Wav == null
select row.PrimaryKey
for a list of keys where your value is null. For listing of null/not null you could do this:
var result = from row in db.Table
select new
{ Key = row.Key, NoWav = (row.Wav == null ? true : false) };
That will generate SQL code similar to this:
SELECT [t0].[WavID] AS [Key],
(CASE
WHEN [t0].[Wav] IS NULL THEN 1
ELSE 0
END) AS [NoWav]
FROM [tblWave] AS [t0]
I'm not clear here, your SQL code is going to return a list of 1s and 0s from your database. Is that what you are looking for? If you have an ID for your record then you could just retrieve that single record with the a condition on the Wav field, null return would indicate no wav, i.e.
var result = from row in dc.Table
where (row.ID == id) && (row.Wav != null)
select new { row.Wav };