I have the following Groovy code to return the max value from the 'id' column from the 'topic' table:
def rs = sql.executeQuery("select max(id) from topic")
def maxId = rs.getLong(1)
It doesn't work, I get the following error:
java.sql.SQLException: Invalid column index
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:113)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:147)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:209)...
Does any one know what the correct code is?
Thanks.
I think it would be easier if you'd use the method firstRow. You can either get the value from the result object by name or by index.
by name:
def row = sql.firstRow("select max(id) as max from topic")
def maxId = row.max
by index:
def row = sql.firstRow("select max(id) from topic")
def maxId = row[0]
Nobody seems to have mentioned that the index in rs.getLong(1) is out of bounds. Getting fields uses a starting index of 0. Binding fields uses a starting index of 1. Why? Historical SQL behaviour.
Related
I was trying to query a DynamoDB table using a Lambda function.
My table's partition key is id. I am trying to query it on another key named dipl_idpp. I unstrood that that is not possible.
I found here a solution: I need to create a Global Secondary Index poitning on the column that I want to query on (in my case dipl_idpp).
I did that on Dynamo. But when I execute my function I still have the same problem:
An error occurred (ValidationException) when calling the Query operation: Query condition missed key schema element: id', 'occurred at index 0')"
This is the code I use:
def query_dipl_dynamo(key_table,valeur_query,name_table):
dynamoDBResource = boto3.resource('dynamodb')
table = dynamoDBResource.Table(name_table)
response = table.query(
KeyConditionExpression=Key(key_table).eq(valeur_query))
df_fr = pd.DataFrame([response['Items']])
if len(df_fr.columns) > 0 :
print("hellooo1")
df = pd.DataFrame([response['Items'][0]])
return valeur_query, df["dipl_libelle"].iloc[0]
//
//
df9_tmp["dipl_idpp"] = df8_tmp.apply(lambda x : query_dipl_dynamo("dipl_idpp",x["num_auto"], "ddb-dev-PS_LibreAcces_Dipl_AutExerc")[0], axis=1)
Should I change something else beside creating the index? Too little documentation is available.
Thank you!
I just found the solution. When we use Indexes we must provide
an argument namde IndexName who takes the name of the index in Dynamo.
I had to change my code to:
def query_dipl_dynamo(key_table,valeur_query,name_table):
dynamoDBResource = boto3.resource('dynamodb')
table = dynamoDBResource.Table(name_table)
response = table.query(
IndexName:"NameOfTheIndexInDynamoDB",
KeyConditionExpression=Key(key_table).eq(valeur_query))
df_fr = pd.DataFrame([response['Items']])
if len(df_fr.columns) > 0 :
df = pd.DataFrame([response['Items'][0]])
return valeur_query, df["dipl_libelle"].iloc[0]
//
//
df9_tmp["dipl_idpp"] = df8_tmp.apply(lambda x : query_dipl_dynamo("dipl_idpp",x["num_auto"], "ddb-dev-PS_LibreAcces_Dipl_AutExerc")[0], axis=1)
I need to set the value of sequence for a IrSequence model instance inside a Python method.
I would have as input values:
the ID of the IrSequence (and getting the ID of the IrSequenceDateRange if dates are used is also possible).
the value for the next value to be used in the sequence.
Given that ID and that value, how can I set up the next value programmatically -i.e. by python source code- for that sequence?
Thanks,
There are two methods to get the next value in a sequence:
1) Given the id:
next_seq = seq_record.next_by_id(cr, uid, seq_id, context)
2) Given the code:
next_seq = seq_record.next_by_code(cr, uid, seq_code, context=context)
But if you want to change the database value directly you can try to write the record:
seq_rec = self.env[ir_sequence].browse(seq_id)
seq_rec.write({'number_next': your_next_sequence})
I hope this helps
I've looked at the documentation in various places to see how to do this, but I haven't had any success. I want to pass in the name of a column into a sql query. I'm using psycopg2 and My most recent attempt was based off of this doc page http://initd.org/psycopg/docs/sql.html#module-psycopg2.sql
Here is my latest attempt, but I get an error IndexError: tuple index out of range that points to the format() where I'm passing in the parameter.
def parse_files(cursor):
for name in column_names:
cursor.execute(
sql.SQL(
"select planet_osm_point.{}, count(*) from planet_osm_point group by planet_osm_point.{}"
).format(sql.Identifier(name)))
for row in cursor:
print(str(row[0]) + str(row[1]))
It's not clear by the given documentation, but it looks like I need to pass in a value inside of the {} specifying what argument I want to use. In this case it's {0}
column_names = ['col1', 'col2']
for column in column_names:
query = sql.SQL('''
select {0}, count(*)
from planet_osm_point pop
group by {0}
''').format(sql.Identifier('pop.' + column))
cursor.execute(query)
for row in cursor.fetchall():
print (str(row[0]) + str(row[1]))
I'm trying to use .extra() where the query return more than 1 result, like :
'SELECT "books_books"."*" FROM "books_books" WHERE "books_books"."owner_id" = %s' % request.user.id
I got an error : only a single result allowed for a SELECT that is part of an expression
Try it on dev-server using sqlite3. Anybody knows how to fix this? Or my query is wrong?
EDIT:
I'm using django-simple-ratings, my model like this :
class Thread(models.Model):
#
#
ratings = Ratings()
I want to display each Thread's ratings and whether a user already rated it or not. For 2 items, it will hit 6 times, 1 for the actual Thread and 2 for accessing the ratings. The query:
threads = Thread.ratings.order_by_rating().filter(section = section)\
.select_related('creator')\
.prefetch_related('replies')
threads = threads.extra(select = dict(myratings = "SELECT SUM('section_threadrating'.'score') AS 'agg' FROM 'section_threadrating' WHERE 'section_threadrating'.'content_object_id' = 'section_thread'.'id' ",)
Then i can print each Thread's ratings without hitting the db more. For the 2nd query, i add :
#continue from extra
blahblah.extra(select = dict(myratings = '#####code above####',
voter_id = "SELECT 'section_threadrating'.'user_id' FROM 'section_threadrating' WHERE ('section_threadrating'.'content_object_id' = 'section_thread'.'id' AND 'section_threadrating'.'user_id' = '3') "))
Hard-coded the user_id. Then when i use it on template like this :
{% ifequal threads.voter_id user.id %}
#the rest of the code
I got an error : only a single result allowed for a SELECT that is part of an expression
Let me know if it's not clear enough.
The problem is in the query. Generally, when you are writing subqueries, they must return only 1 result. So a subquery like the one voter_id:
select ..., (select sectio_threadrating.user_id from ...) as voter_id from ....
is invalid, because it can return more than one result. If you are sure it will always return one result, you can use the max() or min() aggregation function:
blahblah.extra(select = dict(myratings = '#####code above####',
voter_id = "SELECT max('section_threadrating'.'user_id') FROM 'section_threadrating' WHERE ('section_threadrating'.'content_object_id' = 'section_thread'.'id' AND 'section_threadrating'.'user_id' = '3') "))
This will make the subquery always return 1 result.
Removing that hard-code, what user_id are you expecting to retrieve here? Maybe you just can't reduce to 1 user using only SQL.
I need to get maximum page order from database:
int maxOrder = GetSession.Query<Page>().Max(x => x.PageOrder);
The above works if there are rows in the database table, but when table is empty I'm getting:
Value cannot be null.
Parameter name: item
In the way you are doing it is normal to get an exception as the enumerable, that the GetSession.Query<Page>() returns, is empty (because the table is empty as you mentioned).
The exception that you should be getting is: Sequence contains no elements.
The exception you mention in your question is because the item variable (which is irrelevant with the NHiberanate query you list above) is null (line 54 assigns the item property to null).
A safer way to get the max from a property in a table would be the following:
var max = GetSession.CreateCriteria<Page>()
.SetProjection(Projections.Max("PageOrder"))
.UniqueResult();
or using QueryOver with NHibenrate 3.0:
var max = GetSession.QueryOver<Page>()
.Select(
Projections
.ProjectionList()
.Add(Projections.Max<Page>(x => x.PageOrder)))
.List<int>().First();
If the table is empty you will get max = 0
Session.Query<Page>().Max(x => (int?)x.PageOrder)
Note the cast (I'm assuming PageOrder is an int)
If you are having problems with the QueryOver example by tolism7 (InvalidCastException), here's how I got it working:
var max = session.QueryOver<Page>()
.Select(Projections.Max<Page>(x => x.PageOrder))
.SingleOrDefault<object>();
return max == null ? 0 : Convert.ToInt32(max);