As I continue to learn about it, expect to see more blog posts forthcoming in the future… Its interaction with SQL databases – and SQLAlchemy in general – opens up several possibilities to work with data in different ways. The more I use and study pandas, the more it impresses me. Visit the below on-line resources on many of the topics covered in this post for an in-depth look into them:
I think of this as pandas version of the SQL clause ON table_1. The on parameter specifies what key (or index according to the docs) the JOIN should be performed on. “inner: use intersection of keys from both frames, similar to a SQL inner join preserve the order of the left keys.” Below is a portion of the verbiage quoted from the on-line documentation: Next, the how = 'inner' parameter specifies a SQL-like JOIN. First, ‘shoes’ is the DataFrame I am merging with.
Here’s a rundown on the 3 parameters used in this example. For this example, I’ll look at just 3 of them: ‘shoes’, how, and on.
#Pandas joining full
Visit the documentation (link in closing section) for the full range of them. Pandas merge ( ) accepts several optional parameters. Using merge ( ) you can do exactly that, merge DataFrames. Recall both the ‘stats’ and ‘shoes’ DataFrame’s have roughly the same data as that of the read_sql ( ) INNER JOIN query. merge ( ) function, I can retrieve those same results in a slightly different manner versus the actual SQL JOIN query. ON vs USING: Nuances between clauses with LEFT JOIN’s – An observation.Īlthough the read_sql ( ) example works just fine, there are other pandas options for a query like this.What’s missing? Find out using OUTER JOIN’s in MySQL with examples.I have written several posts on JOIN‘s you might like to read if you want to learn more about them. read_sql ( 'SELECT s.day_walked, s.miles_walked, sh.name_brand FROM stats AS s INNER JOIN shoe_brand AS sh ON s.shoe_id = sh.shoe_id WHERE EXTRACT(MONTH FROM s.day_walked) = 1 ', engine )Ġ 2019- 01- 02 1.76 Keen Koven WP (keen-dry ) (Background on this error at: me/e/f405 )Īpparently, you must provide an actual SQL query to read_sql_query ( ) instead of just a table name: Synta圎rror ) syntax error at or near "shoe_brand" #errors below not shown for brevity's sake. The above exception was the direct cause of the following exception: Synta圎rror: syntax error at or near "shoe_brand" read_sql_query ( 'shoe_brand', engine )įile "/home/linux_user_name/pg_py_database/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1244, in _execute_contextĬursor, statement, parameters, contextįile "/home/linux_user_name/pg_py_database/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 552, in do_executeĬursor.
0 kommentar(er)
