Our company is setting up a new Snowflake instance, and we are attempting to migrate some processing currently being done is MS SQL Server. I need to migrate a Table-Valued SQL Function into snowflake. The source function has procedural logic in it, which is not allowed to my knowledge in snowflake UDTFs. I have been searching for a workaround with no success.
To be as specific as I can, I need a function that will take a string for input, decode that string, and return a table with the keys and their corresponding values. I cannot condense all of the logic to split the string and decode the keys into one SQL statement, so Snowflake SQL UDTFs will not work.
I looked into whether a UDTF can call a procedure and somehow I could simply return a result, but it does not look like that will work. Please let me know if there is any way to work around this.
I think Javascript UDTF is what you're looking for in Snowflake:
https://docs.snowflake.com/en/sql-reference/udf-js-table-functions.html
funny I just stumbled onto this as I'm running into the same thing myself. I found there is a SPLIT_TO_TABLE function that may be able to accomplish this. As Greg suggested nesting this together in the form of a CTE combined with a JOIN may allow you to accomplish what you need to do.
Related
I've read the information about BULK COPY page on Npgsql's webpage here. Yet looking at the BULK COPY BeginBinaryExport() and BeginBinaryImport() methods, they both take strings. How would one construct a SQL injection-safe version of a query for BeginBinaryImport() that took query parameters, e.g. didn't return all the rows of a table but only the those that passed a certain filter, such as being on a certain date?
Unfortunately this isn't currently supported. I've opened issue https://github.com/npgsql/npgsql/issues/3841 to track this.
In the meantime you'll have to interpolate parameters as strings into the query, and protect against SQL injection yourself.
In Microsoft Sql Server, there is a proc sys.sp_describe_first_result_set which takes an arbitrary sql query string and returns data describing the types that would be in the result set, were it to be executed. Note, this is describing the results of a complex query, not a table. MSDN reference
Is there anything similar for Postgres?
I tried to do this by creating a stored procedure to create temperory view then check information_schema.columns before droping the view.
There is at the protocol level - in the form of the Describe message in the extended query protocol.
I'm not aware of any SQL-level equivalent for arbitrary SQL strings. Good idea though; raise it on pgsql-general . I suspect it'd be pretty easy to implement.
In fact, a quick look at exec_describe_statement_message in src/backend/tcop/postgres.c shows that the brains are in SendRowDescriptionMessage in src/backend/access/common/printtup.c. It shouldn't be hard to write a simple C extension to do similar work and produce a resultset. Hopefully a couple of hours work if you're familar with the codebase; the idea would be:
Feed the SQL string into the parser/rewriter/planner to obtain a plan
Find the targetlist of the top level node, if any. This will be the RETURNING node for DML, or the top-level Query tlist for a SELECT.
Feed the tlist into ExecTypeFromTL
Loop over the tupledesc entries, skipping resjunk columns by looking them up in the tlist, and emit a row for each non-resjunk output from the query.
So Im new to databases and Im trying to learn the ropes. I have a DB2 database that Im getting familiar with. I was assigned a task where I need to write a method that does a search on the database. The search will take in two parameters, a username and a user id number. If the user and the user id number does not match or if one or the other turns out null then It needs to throw a error. If its valid then it will continue with spitting out information about the user.
I was told to use the findall() function or something similar to it. I was looking online and what I have found is examples that deal with like or ilike and im not sure how something like that will work in my situation. What would be a decent example of how I would start to go about this?
any help is appreciated. Ill post back if I make any progress.
note: Im using groovy/grails. Domain,Controller,View setup.
Is this some homework assignment from school?
findall() is usually a method in regular expressions which I don't think is relevant in here. If you have a SQL database, that means you have a RDBMS which uses SQL as query language. You need to learn about the SELECT command which can look daunting when you look the first the time to the manual but it's actually simple for your case. You need something like:
SELECT userfield1, userfield2,..
FROM myusertable
WHERE myusertable.username = 'uname' AND myusertable.userid = userid
uname and userid are your search parameters. Please note that this SQL query should be done with a PREPARED statement for security reasons.
When you run this query using your database library you get back an array of results which you have to analyze. If it is empty, no user found.
Edit: updated to take into account the use of hibernate
Hibernate uses HQL which is like SQL and has indeed a findAll method. See http://grails.org/doc/latest/ref/Domain%20Classes/findAll.html
First of all before I get into the question, I'll preface this with the fact that I know that this is a "bad" idea. But for business reasons it is something that I have to come up with a solution to, and I'm hoping that someone, somewhere might have some ideas on how to go about this.
I have a SQL Server 2008 R2 table that has a "OtherProperties" column. This column contains various other, somewhat arbitrary additional pieces of information that relate to the records. There is a business need to create a UDF that we can use to query the results, for example.
SELECT *
FROM MyTable
WHERE MyUDFGetValue(myTable.OtherProperties, "LinkedOrder[0]") IS NOT NULL
This would find a record where there was an array of LinkedOrder entries that contained a value at index 0
SELECT *
FROM MyTable
WHERE MyUDFGetValue(myTable.OtherProperties, "SubOrder.OrderId") = 25
This would find a property "orderId" and use its value in a comparison.
Anyone seen an implementation of this? I've seen implementations of functions. Like this JSONParser that take the values into a table which just will not get us what we need query wise. Complexity wise, I don't want to write a full fledged JSON parser, but I can if I need to.
Not sure if this will suit your needs but I read about a CLR JSON serializer/deserializer. You can find it here, http://www.sqlservercentral.com/articles/CLR/74160/
It's been a long time since you asked your question but there is now a solution you can use - JSON Select which provides various functions for different datatypes, for example the JsonInt() function. From one of your examples (assuming OrderId is an int, if not you could use a different function):
SELECT *
FROM MyTable
WHERE dbo.JsonInt(myTable.OtherProperties, 'SubOrder.OrderId') = 25
DISCLOSURE:
I am the author of JSON Select, and as such have an interest in you using it :)
If you cannot use SQL Server 2016 with built-in JSON support, you would need to use CLR e.g. JSONselect, json4sql, or custom code such as http://www.codeproject.com/Articles/1000953/JSON-for-SQL-Server-Part, etc.
When using multivalue parameters in sql reporting services is it more appropriate to implement the list filter using a filter on the dataset itself, the data region control or change the actual query that drives the dataset?
SSRS will support any scenario, so then I ask, is there a reason beyond the obvious of why this should be done at one level over another?
It makes sense to me that modifying the query itself and asking the RDBMS to handle the filtering would be most efficient but maybe I am missing something with respect to how the SSRS Data Processing Extension may handle this scenario?
You are correct. The way to go is to pass the parameters through to the database engine.
Reporting Services should only be ideally used to render content. The less data that you need to pass back to the client web browser, the faster the report will render.
You may find my answer to a similar post regarding using mulit-value parameters to be of use.
Passing multiple values for a single parameter in Reporting Services
Hope this helps but please feel free to pose any further questions you may have.
Cheers,
John
Using table-valued UDF is a good approach, but there is still one issue - in case if this function is called in many places of query, and even inside inner select, there can be performance problem. You can resolve this issue using table variable (or temp table eather):
DECLARE #Param (Value INT)
INSERT INTO #Param (Value)
SELECT Param FROM dbo.fn_MVParam(#sParameterString,',')
...
where someColumn IN(SELECT Value FROM #Param)
so function will be called only once.
Othe thing, if you don't use stored procedure, but embedded SQL query instead, you can just put MVP into query:
...
where someColumn IN(#Param)
...
Use the RDBMS to do the main filtering
SSRS provides filtering for the purposes on data driven display and/or dynamic display. Especially useful for sub reports etc