I'm using NHibernate with Mapping by Code and I have a property that is created by this formula.
Property(x => x.IsInOverdue,
mapper => mapper
.Formula("(SELECT (state_ <> 3 AND invoice_uniqueAlias.duedate_ < NOW()) " +
" FROM _invoice AS invoice_uniqueAlias "+
" WHERE invoice_uniqueAlias.invoice_id = issuedinvoice_key)"));
It works perfectly, this sql is inserted as subselect in all queries...
But I would need to add 1 day to invoice_uniqueAlias.duedate_ value. We are using PostgreSQL where the syntax for it is: invoice_uniqueAlias.duedate_ + interval '1 day'
But when I put it in mapper.Formula, NHibernate thinks that interval is a name of column and in all queries tries to add table prefix before interval keyword. The generated SQL then looks like:
... (SELECT (issuedinvo0_.state_ <> 3
AND (invoice_uniqueAlias.duedate_ + (issuedinvo0_.interval '1 day')) < NOW()) ...
I tried to put interval keyword in [, `, put statement interval + '1 day' to brackets, but it didn't help. Any suggestions how to handle it correctly in NHibernate or how it is possible to write it in Postgres without using + interval syntax?
In case, we need NHibernate to treat some words (key words) as part of the underlying DB engine dialect, we have to just extend it.
One way would be the create custom dialect:
public class CustomPostgreDialect : PostgreSQL82Dialect
{
public CustomPostgreDialect()
{
RegisterKeyword("interval");
}
}
And now just use it:
<property name="dialect">My.Namespace.CustomPostgreDialect,My.Data</property>
Some similar issue - Using SQL CONVERT function through nHibernate Criterion (with the similar solution in this answer)
Related
I want to delete all database entries in my Postgres database that are older than X minutes. My prepared statement in go looks like this:
delete
from my_table
where expires < (to_timestamp($1) - '$2 minutes'::interval);
How can I correctly pass the second parameter $2?
PS: I know there's different statements to solve the problem, but I am explicitly interested in how to pass parameters that are quoted.
There is no way to interpolate a parameter into a string literal.
A possible solution for your case would be to multiply a number with an interval:
where expires < (to_timestamp($1) - $2 * '1 minute'::interval)
You can cast the parameter to text and then concatenate it with the string ' minutes'.
delete from my_table
where expires < (to_timestamp($1) - ($2::text || ' minutes')::interval
UPDATE: actually, since postgres does have a any || text operator, the result of which is text, you shouldn't need to type cast the parameter.
You can use make_interval
delete from my_table
where expires < (to_timestamp($1) - make_interval(mins => $2));
You can also parametrize the entire interval string instead. This removes the need for an intermediate cast to text and concat.
query := `
delete from my_table
where expires < (to_timestamp($1) - $2::interval);
`
interval := fmt.Sprintf("%d minutes", mins)
db.Exec(query, timestamp, interval)
I'm trying to use Npgsql and/or Dapper to query a table and I keep running into Npgsql.PostgresException 42601: syntax error at or near "$1".
Here is what I've got trying it with NpgsqlCommand:
using (var conn = new NpgsqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["postgres"].ConnectionString))
{
conn.Open();
using (NpgsqlCommand command = new NpgsqlCommand("select * from Logs.Logs where Log_Date > current_date - interval #days day;", conn))
{
command.Parameters.AddWithValue("#days", days);
var reader = command.ExecuteReader();
I've also tried it with Dapper(my preferred method) with:
using (var conn = new NpgsqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["postgres"].ConnectionString))
{
conn.Open();
var logs = conn.Query<Log>("select * from Logs.Logs where Log_Date > current_date - interval #days day;", new {days = days});
Either way I get the same Npgsql.PostgresException 42601: syntax error at or near "$1" error. The Statement in the Exception shows: select * from Logs.Logs where Log_Date > current_date - interval $1 day
Note, if I do the following it works fine, but it's not properly parameterized:
var logs = conn.Query<Log>("select * from Logs.Logs where Log_Date > current_date - interval '" + days + "' day;");
What am I doing wrong? I very much appreciate any feedback. Thank you.
PostgreSQL doesn't allow you to stick a parameter anywhere in a query. What you want can be achieved with the following:
var command = new NpgsqlCommand("select * from Logs.Logs where Log_Date > current_date - #days", conn))
command.Parameters.AddWithValue("#days", TimeSpan.FromDays(days));
This way you're passing the interval directly from Npgsql to PostgreSQL, rather than a part of the expression designed to create that interval.
i got this error using DapperExtensions
adding
DapperExtensions.DapperExtensions.SqlDialect = new PostgreSqlDialect();
DapperAsyncExtensions.SqlDialect = new PostgreSqlDialect();
before creating the connection fixed the issue
To subtract days from a date (assuming log_date is data type date), you can simplify:
"SELECT * FROM logs.logs WHERE log_date > CURRENT_DATE - #days;"
And provide #days as unquoted numeric literal (digits only) - which is taken to be an integer. This is even more efficient, since date - integer returns date, while date - interval returns timestamp.
The manual about interval input.
So the query below is probably not the most efficient, buy still, I am wondering why it is returning no result, even though the SQL counterpart does. There is no error, I am just getting no result. Is it maybe not the correct equivalent for the query I wrote in MySQL?
This is the JPA JPQL.
Query query = em.createQuery("SELECT sub FROM Subscription sub WHERE "
+ "sub.isSuspended = 0 AND "
+ "(SELECT i FROM Invoice i WHERE i.dateDue < CURRENT_DATE AND i.datePaid IS NULL "
+ "GROUP BY i HAVING COUNT(i.idInvoice) > 2) MEMBER OF sub.invoices");
And this is the SQL from MySQL.
SELECT * from subscription
WHERE subscription.is_suspended = 0 AND id_subscription IN
(SELECT id_subscription FROM invoice
WHERE date_due < CURDATE() AND date_paid IS NULL
GROUP BY id_subscription
HAVING COUNT(*) > 2)
The two queries are not the same. To use the actual query use the NativeQuery createNativeQuery() instead of Query.
In your case the JPA version seems to have syntax errors.
After the AND you are missing the IN operator.
In the nested query you are selecting i instead of something like i.idInvoice
The JPA query should look like
SELECT sub FROM Subscription sub
WHERE sub.isSuspended = 0
AND sub.idSubscription IN
(SELECT i.idInvoice
FROM Invoice i
WHERE i.dateDue < CURRENT_DATE AND i.datePaid IS NULL
GROUP BY i.idInvoice
HAVING COUNT(i.idInvoice) > 2);
I am trying to do this simple query, but it does not work. Thanks.
SELECT * FROM TSimple where (start_date < '2012-04-20' and end_date is null) or
(end_date > '2012-04-20' and start_date < '2012-04-20')
class TSimple (models.Model):
start_date = models.DateTimeField()
end_date = models.DateTimeField(blank=True, null=True)
...
class TSimpleResource(ModelResource):
def dehydrate(self, bundle):
request_method = bundle.request.META['REQUEST_METHOD']
if request_method=='GET':
new_date = bundle.request.GET.get('new_date', '')
qs = TSimple.objects.raw(
'SELECT * FROM TSimple where (start_date<=\'' +
new_date + '\' and end_date>=\'' +
new_date + '\') or (start_date<=\'' + new_date +
'\' and end_date is null)')
ret_list = [row for row in qs]
// NOT WORK. Not able to get correct json data in javascript.
// It needs return bundle. HOW to replace bundle?
// Is this correct way to do it?
return ret_list
else:
// This is ok.
return bundle
I have following questions:
1) (raw sql method) If implementing in dehydrate method is correct way to do it? If it is, above does not work. It should return bundle object. How to construct new bundle?
If above method is ok, I noticed that bundle already constructed .data field with default query(?), which will be thrown away with new query. That raise the questions if this is right way to do it.
2) If there are other raw sql method to do it? Where to execute the sql?
3) How to do it in filter?
4) I know sql and not familiar with complex filter. That's why I am trying to use raw sql method to do quick prototype. What are the draw back? I noticed that using Tastypie has many unnecessary queries which I don't know how to get rid of it. Example, query on table with foreign key trigger query to another table's data, which I don't want to get.
I figure out the filter and it seems worked. But I am still interested in raw sql.
def apply_filters(self, request, applicable_filters):
base_filter = super(TSimpleResource, self).apply_filters(request,
applicable_filters)
new_date = request.GET.get('new_date', None)
if new_date:
qset = (
(
Q(start_date__lte=new_date) &
Q(end_date__gte=new_date)
) |
(
Q(start_date__lte=new_date) &
Q(end_date__isnull=True)
)
)
base_filter = base_filter.filter(qset)
return base_filter
Why doesn't this work (when parameter is set to 1) :
SELECT * FROM TABLE WHERE TIMESTAMPFIELD > (CURRENT_TIMESTAMP - ?)
But this works :
SELECT * FROM TABLE WHERE TIMESTAMPFIELD > (CURRENT_TIMESTAMP - 1)
I get error message: "conversion error from string "39723.991882951" "
I'm using Firebird 2.1
EDIT:
I found the answer myself with a little help:
SELECT * FROM TABLE WHERE TIMESTAMPFIELD > (CURRENT_TIMESTAMP - CAST(? as DECIMAL(18,9))
Works if the parameter is given as float value.
What do you want to do exactly? Maybe I can be more helpfull with more details.
SELECT * FROM TABLE WHERE TIMESTAMPFIELD > (CURRENT_TIMESTAMP - ?)
How do you set your parameter in your code? Which language do you use?
If you use Delphi, then your parameter should be passed as Float. Ie:
MyQuery.ParamByName('delta').asFloat := 0.1;
Try this and tell us if it's working
HTH