Handling complex SQL statements with Python and SQLAlchemy





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I am building an analytics page backed up with Python(Flask) and Redshift as data source. Data is presented in a start schema, so all I want to do is basic aggregation and filtering in specified time frame (sounds not like a rocket science). Though I can't find any elegant way to do this.



Let's say I have a SQL query that nicely provides daily stats for current month.



with current_month as (
select date
from date_d
where month_name = 'November' AND year_actual = '2018'
order by date
),
filtered as (
select date ,fact.id, fact.created_id,
from fact
join date_d ON date_d.id = fact.created_id
where date_d.month_name = 'November' AND date_d.year_actual = '2018' AND fact.foo = 'bar'
),
total as (
SELECT COUNT(id),DATE(date)
from filtered GROUP BY 2),

SELECT current_month.date, COALESCE(total.count,0) as total
from current_month
LEFT JOIN total ON current_month.date = total.date
group by 1,
order by current_month.date


Is there any way I can execute this query and load results into some predefined data structure? I looked at SQLAlchemy, because I didn't feel like executing raw SQL Queries, but ORM looks useless here.
Looks like the only way is to execute raw SQL and load it into some sort of schema (using marshmallow).
I looked at this article which is close but not that elaborate.



Maybe I am missing something? People should do such things rather often.
Or maybe my approach is wrong over all?



P.S. Simple filtering works perfectly on my schema with Flask-Restless










share|improve this question





























    0















    I am building an analytics page backed up with Python(Flask) and Redshift as data source. Data is presented in a start schema, so all I want to do is basic aggregation and filtering in specified time frame (sounds not like a rocket science). Though I can't find any elegant way to do this.



    Let's say I have a SQL query that nicely provides daily stats for current month.



    with current_month as (
    select date
    from date_d
    where month_name = 'November' AND year_actual = '2018'
    order by date
    ),
    filtered as (
    select date ,fact.id, fact.created_id,
    from fact
    join date_d ON date_d.id = fact.created_id
    where date_d.month_name = 'November' AND date_d.year_actual = '2018' AND fact.foo = 'bar'
    ),
    total as (
    SELECT COUNT(id),DATE(date)
    from filtered GROUP BY 2),

    SELECT current_month.date, COALESCE(total.count,0) as total
    from current_month
    LEFT JOIN total ON current_month.date = total.date
    group by 1,
    order by current_month.date


    Is there any way I can execute this query and load results into some predefined data structure? I looked at SQLAlchemy, because I didn't feel like executing raw SQL Queries, but ORM looks useless here.
    Looks like the only way is to execute raw SQL and load it into some sort of schema (using marshmallow).
    I looked at this article which is close but not that elaborate.



    Maybe I am missing something? People should do such things rather often.
    Or maybe my approach is wrong over all?



    P.S. Simple filtering works perfectly on my schema with Flask-Restless










    share|improve this question

























      0












      0








      0








      I am building an analytics page backed up with Python(Flask) and Redshift as data source. Data is presented in a start schema, so all I want to do is basic aggregation and filtering in specified time frame (sounds not like a rocket science). Though I can't find any elegant way to do this.



      Let's say I have a SQL query that nicely provides daily stats for current month.



      with current_month as (
      select date
      from date_d
      where month_name = 'November' AND year_actual = '2018'
      order by date
      ),
      filtered as (
      select date ,fact.id, fact.created_id,
      from fact
      join date_d ON date_d.id = fact.created_id
      where date_d.month_name = 'November' AND date_d.year_actual = '2018' AND fact.foo = 'bar'
      ),
      total as (
      SELECT COUNT(id),DATE(date)
      from filtered GROUP BY 2),

      SELECT current_month.date, COALESCE(total.count,0) as total
      from current_month
      LEFT JOIN total ON current_month.date = total.date
      group by 1,
      order by current_month.date


      Is there any way I can execute this query and load results into some predefined data structure? I looked at SQLAlchemy, because I didn't feel like executing raw SQL Queries, but ORM looks useless here.
      Looks like the only way is to execute raw SQL and load it into some sort of schema (using marshmallow).
      I looked at this article which is close but not that elaborate.



      Maybe I am missing something? People should do such things rather often.
      Or maybe my approach is wrong over all?



      P.S. Simple filtering works perfectly on my schema with Flask-Restless










      share|improve this question














      I am building an analytics page backed up with Python(Flask) and Redshift as data source. Data is presented in a start schema, so all I want to do is basic aggregation and filtering in specified time frame (sounds not like a rocket science). Though I can't find any elegant way to do this.



      Let's say I have a SQL query that nicely provides daily stats for current month.



      with current_month as (
      select date
      from date_d
      where month_name = 'November' AND year_actual = '2018'
      order by date
      ),
      filtered as (
      select date ,fact.id, fact.created_id,
      from fact
      join date_d ON date_d.id = fact.created_id
      where date_d.month_name = 'November' AND date_d.year_actual = '2018' AND fact.foo = 'bar'
      ),
      total as (
      SELECT COUNT(id),DATE(date)
      from filtered GROUP BY 2),

      SELECT current_month.date, COALESCE(total.count,0) as total
      from current_month
      LEFT JOIN total ON current_month.date = total.date
      group by 1,
      order by current_month.date


      Is there any way I can execute this query and load results into some predefined data structure? I looked at SQLAlchemy, because I didn't feel like executing raw SQL Queries, but ORM looks useless here.
      Looks like the only way is to execute raw SQL and load it into some sort of schema (using marshmallow).
      I looked at this article which is close but not that elaborate.



      Maybe I am missing something? People should do such things rather often.
      Or maybe my approach is wrong over all?



      P.S. Simple filtering works perfectly on my schema with Flask-Restless







      python sql sqlalchemy data-analysis star-schema






      share|improve this question













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      asked Nov 16 '18 at 16:40









      Semant1kaSemant1ka

      307414




      307414
























          1 Answer
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          Try Pandas and Pyodbc:



          import pandas as pd
          import pyodbc

          server = 'mysrvr'
          db = 'mydb'
          conn = pyodbc.connect('DRIVER={SQL Server};SERVER='+server+';DATABASE='+db+';Trusted_Connection=yes')

          sql = "select col1, col2, col3 from mytable"

          my_dataframe = pd.read_sql(sql,conn)


          my_dataframe will be your data frame/data structure.






          share|improve this answer
























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            1 Answer
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            active

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            0














            Try Pandas and Pyodbc:



            import pandas as pd
            import pyodbc

            server = 'mysrvr'
            db = 'mydb'
            conn = pyodbc.connect('DRIVER={SQL Server};SERVER='+server+';DATABASE='+db+';Trusted_Connection=yes')

            sql = "select col1, col2, col3 from mytable"

            my_dataframe = pd.read_sql(sql,conn)


            my_dataframe will be your data frame/data structure.






            share|improve this answer




























              0














              Try Pandas and Pyodbc:



              import pandas as pd
              import pyodbc

              server = 'mysrvr'
              db = 'mydb'
              conn = pyodbc.connect('DRIVER={SQL Server};SERVER='+server+';DATABASE='+db+';Trusted_Connection=yes')

              sql = "select col1, col2, col3 from mytable"

              my_dataframe = pd.read_sql(sql,conn)


              my_dataframe will be your data frame/data structure.






              share|improve this answer


























                0












                0








                0







                Try Pandas and Pyodbc:



                import pandas as pd
                import pyodbc

                server = 'mysrvr'
                db = 'mydb'
                conn = pyodbc.connect('DRIVER={SQL Server};SERVER='+server+';DATABASE='+db+';Trusted_Connection=yes')

                sql = "select col1, col2, col3 from mytable"

                my_dataframe = pd.read_sql(sql,conn)


                my_dataframe will be your data frame/data structure.






                share|improve this answer













                Try Pandas and Pyodbc:



                import pandas as pd
                import pyodbc

                server = 'mysrvr'
                db = 'mydb'
                conn = pyodbc.connect('DRIVER={SQL Server};SERVER='+server+';DATABASE='+db+';Trusted_Connection=yes')

                sql = "select col1, col2, col3 from mytable"

                my_dataframe = pd.read_sql(sql,conn)


                my_dataframe will be your data frame/data structure.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 16 '18 at 16:55









                CSYCSY

                1155




                1155
































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