Union query between multiple tables

[Justvuur]

Hi All,

I would like to do a union between 3 or 4 tables using the all powerful sqlalchemy. The tables have about 3 columns that are the same but each table has 2 different columns.

Is it possible to do a query as below in sqlalchemy?

Select Col1, Col2, Col3, Col4, Col5 from Table1

Union

Select Col1, Col2, Col3, Null as Col4, Null as Col5 from Table2

[Mike Bayer]

yes, for example with select():

s1 = select([t.c.c1, t.c.c2, t.c.c3])

s2 = select([t2.c.c1, t.c.c2, null().label('col4'), null.label('col5')])

u1 = union(s1, s2)

I'd recommend using union() and select() to create these queries.  the ORM Query.union() method is not as easy to use and long term the above technique with union() and select() will be how it's done.

--

SQLAlchemy -

The Python SQL Toolkit and Object Relational Mapper

 

http://www.sqlalchemy.org/

 

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description.

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[Justvuur]

Thanks Mike! You are the man!

On Wednesday, 3 June 2020 00:12:19 UTC+2, Mike Bayer wrote:

yes, for example with select():

s1 = select([t.c.c1, t.c.c2, t.c.c3])

s2 = select([t2.c.c1, t.c.c2, null().label('col4'), null.label('col5')])

u1 = union(s1, s2)

I'd recommend using union() and select() to create these queries.  the ORM Query.union() method is not as easy to use and long term the above technique with union() and select() will be how it's done.

On Tue, Jun 2, 2020, at 2:09 PM, Justvuur wrote:

Hi All,

I would like to do a union between 3 or 4 tables using the all powerful sqlalchemy. The tables have about 3 columns that are the same but each table has 2 different columns.

Is it possible to do a query as below in sqlalchemy?

Select Col1, Col2, Col3, Col4, Col5 from Table1

Union

Select Col1, Col2, Col3, Null as Col4, Null as Col5 from Table2

--

SQLAlchemy -

The Python SQL Toolkit and Object Relational Mapper

 

http://www.sqlalchemy.org/

 

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description.

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