I am facing a strange problem trying to execute a simple request using laravel-doctrine/orm v1.2.5 on Lumen v5.2.7. with an Oracle database.
When I create a query with the query builder containing more than 2 parameters, I get no results, even though I am expecting a result set.
$conn = $this->getEntityManager()->getConnection();
$queryBuilder = $conn->createQueryBuilder();
$queryBuilder->select('*')
->from('SYNCHS')
->where('SYNCHS.CLIENT_ID = :clientId')
->andWhere('SYNCHS.TOP_CLIENT_ID = :topClientId')
->andWhere('SYNCHS.ID = :synchId');
$queryBuilder->setParameter('clientId', $clientId)
->setParameter('topClientId', $topClientId)
->setParameter('synchId', $synchId);
echo $queryBuilder->getSQL();
var_dump($queryBuilder->getParameters());
$stmt = $queryBuilder->execute();
var_dump($stmt);
$results = $stmt->fetchAll();
dd($results);
If I comment any one of the where/addwhere clause, I end up with the expected result set, but if I have more than 2 parameters bound in the query, it returns nothing (of course it should return something with the passed parameters).
For every scenari:
I can see all my parameters are bound in the query builder var_dump($queryBuilder->getParameters());
Copy paste of the echo $queryBuilder->getSQL(); in Toad (oracle) setting the parameters with the values displayed by the var_dump($queryBuilder->getParameters()); give me 1 row (expected result). So I am sure that my query is correct.
I've looked for hours on google but no relevant result appeared for this problem. Thanks
I have a dataset in BigQuery. This dataset contains multiple tables.
I am doing the following steps programmatically using the BigQuery API:
Querying the tables in the dataset - Since my response is too large, I am enabling allowLargeResults parameter and diverting my response to a destination table.
I am then exporting the data from the destination table to a GCS bucket.
Requirements:
Suppose my process fails at Step 2, I would like to re-run this step.
But before I re-run, I would like to check/verify that the specific destination table named 'xyz' already exists in the dataset.
If it exists, I would like to re-run step 2.
If it does not exist, I would like to do foo.
How can I do this?
Thanks in advance.
Alex F's solution works on v0.27, but will not work on later versions. In order to migrate to v0.28+, the below solution will work.
from google.cloud import bigquery
project_nm = 'gc_project_nm'
dataset_nm = 'ds_nm'
table_nm = 'tbl_nm'
client = bigquery.Client(project_nm)
dataset = client.dataset(dataset_nm)
table_ref = dataset.table(table_nm)
def if_tbl_exists(client, table_ref):
from google.cloud.exceptions import NotFound
try:
client.get_table(table_ref)
return True
except NotFound:
return False
if_tbl_exists(client, table_ref)
Here is a python snippet that will tell whether a table exists (deleting it in the process--careful!):
def doesTableExist(project_id, dataset_id, table_id):
bq.tables().delete(
projectId=project_id,
datasetId=dataset_id,
tableId=table_id).execute()
return False
Alternately, if you'd prefer not deleting the table in the process, you could try:
def doesTableExist(project_id, dataset_id, table_id):
try:
bq.tables().get(
projectId=project_id,
datasetId=dataset_id,
tableId=table_id).execute()
return True
except HttpError, err
if err.resp.status <> 404:
raise
return False
If you want to know where bq came from, you can call build_bq_client from here: http://code.google.com/p/bigquery-e2e/source/browse/samples/ch12/auth.py
In general, if you're using this to test whether you should run a job that will modify the table, it can be a good idea to just do the job anyway, and use WRITE_TRUNCATE as a write disposition.
Another approach can be to create a predictable job id, and retry the job with that id. If the job already exists, the job already ran (you might want to double check to make sure the job didn't fail, however).
Enjoy:
def doesTableExist(bigquery, project_id, dataset_id, table_id):
try:
bigquery.tables().get(
projectId=project_id,
datasetId=dataset_id,
tableId=table_id).execute()
return True
except Exception as err:
if err.resp.status != 404:
raise
return False
There is an edit in exception.
you can use exists() now to check if dataset exists same with table
BigQuery exist documentation
recently big query introduced so called scripting statements that can be quite a game changer for some flows.
check them out here:
https://cloud.google.com/bigquery/docs/reference/standard-sql/scripting
Now for example to check if table exists you can use something like this:
sql = """
BEGIN
IF EXISTS(SELECT 1 from `YOUR_PROJECT.YOUR_DATASET.YOUR_TABLE) THEN
SELECT 'table_found';
END IF;
EXCEPTION WHEN ERROR THEN
# you can print your own message like above or return error message
# however google says not to rely on error message structure as it may change
select ##error.message;
END;
"""
With my_bigquery being an instance of class google.cloud.bigquery.Client (already authentified and associated to a project):
my_bigquery.dataset(dataset_name).table(table_name).exists() # returns boolean
It does an API call to test for the existence of the table via a GET request
Source: https://googlecloudplatform.github.io/google-cloud-python/0.24.0/bigquery-table.html#google.cloud.bigquery.table.Table.exists
It works for me using 0.27 of the Google Bigquery Python module
Inline SQL Alternative
tarheel's answer is probably the most correct at this point in time
but I was considering the comment from Ivan above that "404 could also mean the resource is not there for a bunch of reasons", so here is a solution that should always successfully run a metadata query and return a result.
It's not the fastest, because it always has to run the query, bigquery has overhead for small queries
A trick I've seen previously is to query information_schema for a (table) object, and union that to a fake query that ensures a record is always returned even if the the object doesn't. There's also a LIMIT 1 and an ordering to ensure the single record returned represents the table, if it does exist. See the SQL in the code below.
In spite of doc claims that Bigquery standard SQL is ISO compliant, they don't support information_schema, but they do have __table_summary__
dataset is required because you can't query __table_summary__ without specifying dataset
dataset is not a parameter in the SQL because you can't parameterize object names without sql injection issues (apart from with the magical _TABLE_SUFFIX, see https://cloud.google.com/bigquery/docs/querying-wildcard-tables )
#!/usr/bin/env python
"""
Inline SQL way to check a table exists in Bigquery
e.g.
print(table_exists(dataset_name='<dataset_goes_here>', table_name='<real_table_name'))
True
print(table_exists(dataset_name='<dataset_goes_here>', table_name='imaginary_table_name'))
False
"""
from __future__ import print_function
from google.cloud import bigquery
def table_exists(dataset_name, table_name):
client = bigquery.Client()
query = """
SELECT table_exists FROM
(
SELECT true as table_exists, 1 as ordering
FROM __TABLES_SUMMARY__ WHERE table_id = #table_name
UNION ALL
SELECT false as table_exists, 2 as ordering
) ORDER by ordering LIMIT 1"""
query_params = [bigquery.ScalarQueryParameter('table_name', 'STRING', table_name)]
job_config = bigquery.QueryJobConfig()
job_config.query_parameters = query_params
if dataset_name is not None:
dataset_ref = client.dataset(dataset_name)
job_config.default_dataset = dataset_ref
query_job = client.query(
query,
job_config=job_config
)
results = query_job.result()
for row in results:
# There is only one row because LIMIT 1 in the SQL
return row.table_exists
I'm using NHibernate 3.2 and I have a repository method that looks like:
public IEnumerable<MyModel> GetActiveMyModel()
{
return from m in Session.Query<MyModel>()
where m.Active == true
select m;
}
Which works as expected. However, sometimes when I use this method I want to filter it further:
var models = MyRepository.GetActiveMyModel();
var filtered = from m in models
where m.ID < 100
select new { m.Name };
Which produces the same SQL as the first one and the second filter and select must be done after the fact. I thought the whole point in LINQ is that it formed an expression tree that was unravelled when it's needed and therefore the correct SQL for the job could be created, saving my database requests.
If not, it means all of my repository methods have to return exactly what is needed and I can't make use of LINQ further down the chain without taking a penalty.
Have I got this wrong?
Updated
In response to the comment below: I omitted the line where I iterate over the results, which causes the initial SQL to be run (WHERE Active = 1) and the second filter (ID < 100) is obviously done in .NET.
Also, If I replace the second chunk of code with
var models = MyRepository.GetActiveMyModel();
var filtered = from m in models
where m.Items.Count > 0
select new { m.Name };
It generates the initial SQL to retrieve the active records and then runs a separate SQL statement for each record to find out how many Items it has, rather than writing something like I'd expect:
SELECT Name
FROM MyModel m
WHERE Active = 1
AND (SELECT COUNT(*) FROM Items WHERE MyModelID = m.ID) > 0
You are returning IEnumerable<MyModel> from the method, which will cause in-memory evaluation from that point on, even if the underlying sequence is IQueryable<MyModel>.
If you want to allow code after GetActiveMyModel to add to the SQL query, return IQueryable<MyModel> instead.
You're running IEnumerable's extension method "Where" instead of IQueryable's. It will still evaluate lazily and give the same output, however it evaluates the IQueryable on entry and you're filtering the collection in memory instead of against the database.
When you later add an extra condition on another table (the count), it has to lazily fetch each and every one of the Items collections from the database since it has already evaluated the IQueryable before it knew about the condition.
(Yes, I would also like to be the extensive extension methods on IEnumerable to instead be virtual members, but, alas, they're not)
Using Ruby DBI, how can I check if a record set is empty? (without iterating through it or doing a count query)
sth = dbh.prepare("select * from things WHERE created_at > '#{start}'")
sth.execute
You could always just ask the result object:
res = sth.execute
res.num_rows
The operation will have to pull down all matching records, though, so if you only need a count, you might want to select that directly.
Also escape your SQL. You cannot just put arbitrary strings in there. This is better:
sth = dbh.prepare("select * from things WHERE created_at > '%s'" % sth.escape_string(start))
I've got a LINQ query that looks like this (at the end):
var query = from myTable0 ...
where myTable1.attributeId == 123 && (bunchaStrings.Contains(myTable1.attributeName)) && myTable2.yesNoValue == 'Y'
When I see the query it turns into this
SELECT ... FROM ... INNER JOIN ... WHERE ... AND (UNICODE([t3].[yesNoValue]) = #p3
So what's happening here is that the value of 'Y' is getting turned into '89' via the UNICODE function. That's all fine, but I'd really like to just be able to see the value of #p3 directly and I can't figure out how to see that value via any methods available from my var.
I would recommend piping the generated SQL out to the output window. There you will be able to see the whole SQL and your parameters values. Then it can also be logged.
Code for it can be found here ->
http://www.u2u.info/Blogs/Kris/Lists/Posts/Post.aspx?ID=11
Or an easier method (if you've got a handy console around):
MyDataContext context = new MyDataContext()
context.Log = Console.Out
You may also be interested in the LINQ to SQL Visualizer : http://weblogs.asp.net/scottgu/archive/2007/07/31/linq-to-sql-debug-visualizer.aspx