> I have a query in sqlalchemy like below where I lookup contract# in mssql.
>>>> How do I enforce the varchar instead of nvarchar? I tried converting my
>>>> field to "str(mycurrent)" but that didn't do anything. Is there some other
>>>> spot to force VARCHAR to be sent?
>>>>
>>>
>>>
>>> this just came up in
>>> https://bitbucket.org/zzzeek/sqlalchemy/issues/4161/sql-server-string-use-case,
>>>
>>> in that case they are using typed parameters:
>>>
>>> String(50, convert_unicode='force')
>>>
>>> if you're dealing w/ the raw string like that try this:
>>>
>>> execute(text("select ... where foo =
>>> :mycurrent").bindparams(bindparam("mycurrent",
>>> type_=String(convert_unicode='force')))
>>>
>>> let me know if that works b.c. this has to be in the docs
>>>
>>
>>
>>
>>
Hello Mike.
Do you have a minute to guide me on the syntax. I can't figure this out,
and I need to fix this performance problem. If I can't figure it out I'll
just create stored procedures to replace the query.
Here is the code again:
# 'm struggling with the syntax here for the bind param. How do I convert
from session.execut(stmt,params) to your bindparams? I can't just cast the
variable I'm passing to correct format?
# Keep in mind that the value is either some sqlalchemy object.columname or
some 'other system' variable from a loop aka (for row in First_query:
mycontract=row.contract_no
#I need to go from to :
>
> From
> p=session.execute("select PZ.p_id,PZ.pimage_num from dbo.P with(nolock)
> inner join dbo.PZ PZ with(nolock) on PZ.p_id = p.p_id inner join dbo.D D
> with(nolock) on D.p_id = p.p_id AND D.pimage_num=PZ.pimage_num where
> p.contract=:mycontract and D.srtype_id
> =5",params={'mycontract':str(mycontract)}).fetchall()
>
> To:
> from sqlalchmy import bindparams
> ##mycurrent=someobject.contract_no
> mycurrent='ABC123'
>
> I tried these syntax but it doesn;t work:
#Incorrect Syntax#1?
>
> (bad) p=session.execute(text("select PZ.p_id,PZ.pimage_num from dbo.P
> with(nolock) inner join dbo.PZ PZ with(nolock) on PZ.p_id = p.p_id inner
> join dbo.D D with(nolock) on D.p_id = p.p_id AND D.pimage_num=PZ.pimage_num
> where p.contract=:mycontract and D.srtype_id
> =5").bindparam('mycontract'),params={'mycontract':str(mycontract)}).fetchall()
> AttributeError: 'TextClause' object has no attribute 'bindparam'
>
> #Incorrect Syntax#2?
> (bad) p=session.execute("select PZ.p_id,PZ.pimage_num from dbo.P
> with(nolock) inner join dbo.PZ PZ with(nolock) on PZ.p_id = p.p_id inner
> join dbo.D D with(nolock) on D.p_id = p.p_id AND D.pimage_num=PZ.pimage_num
> where p.contract=:mycontract and D.srtype_id
> =5").bindparam('mycontract').fetchall()
> A value is required for bind parameter 'mycontract'
>
>
> #Incorrect Syntax #3?
This in the link
<https://bitbucket.org/zzzeek/sqlalchemy/issues/4161/sql-server-string-use-case>
indicated.
Page says that a "String(50).with_variant(String(50,
convert_unicode='force'), 'mssql')" has worked for Jan K. but it doesn't
really say how does somebody converts their variable into correct type
string:
> like:
> mycontract=cast(mycontract, String(convert_unicode='force'))
>
>
> #Incorrect Syntax #4?
> Since I'm passing params right after my statement should the bindparam be
> in params section?
> something along:
> params={'mycontract':sqlalchemy.string(mycontract).convert_unicode='force')})
>
> The easiest way would be to convert mycontract into proper
> String(convert_unicode='force') and pass mycontract as in my original query?
>
>
>
> You can find that the query that uses NVARCHAR does an index scan has
> 30,909 logical reads on the dbo.P table. It also uses 890 ms of CPU and
> has a total elapsed time of 938 ms.
>
> The query that uses VARCHAR does an index seek and has 7 logical reads on
> the dbo.P table. It uses 0 ms of CPU and has a total elapsed time of 11 ms.
>
>
> p=*session.execute*("select PZ.p_id,PZ.pimage_num from dbo.P
> with(nolock) inner join dbo.PZ PZ with(nolock) on PZ.p_id = p.p_id inner
> join dbo.D D with(nolock) on D.p_id = p.p_id AND D.pimage_num=PZ.pimage_num
> where p.current=:mycurrent and D.srtype_id
> =5",params={'mycurrent':str(mycurrent)}).fetchall()
>
>
>
>
>
> [image: Inline image 1]
>
>
>
>
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