question :)

[Massimiliano della Rovere]

Greetings,

is it possible using sqlalchemy core to obtain the following code:

[...]

WHERE (column1, column2) = (value1, value2)

this is useful to use multi columnar indexes having column1 and column2 in the two leftmost position and in later position columns that I put in the SELECT section. 

[Mike Bayer]

yes the tuple construct provides this:

https://docs.sqlalchemy.org/en/13/core/sqlelement.html?highlight=tuple#sqlalchemy.sql.expression.tuple_

>>> from sqlalchemy import select, column, tuple_

>>> stmt = select([column('q')]).where(tuple_(column('x'), column('y')) == tuple_(3, 4))

>>> print(stmt)

SELECT q

WHERE (x, y) = (:param_1, :param_2)

however, tuples are not supported on all backends and it's safer to use AND:

>>> from sqlalchemy import and_

>>> stmt = select([column('q')]).where(and_(column('x') == 3, column('y') == 4))

>>> print(stmt)

SELECT q

WHERE x = :x_1 AND y = :y_1

From a Python perspective, there's no real reason to use one or the other, as either one can be generated programmatically.

the tuple_ construct is provided mostly to support IN expressions against composite values, for equality it's not strictly necessary.

--

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The Python SQL Toolkit and Object Relational Mapper

 

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