Similar questions have been asked before but I’ve still been unable to identify a solution for this. My code: try: connection = cx_Oracle.connect(ORACLE_CONNECT) logger.info(“…
Tag: python
Pyspark: cast array with nested struct to string
I have pyspark dataframe with a column named Filters: “array>” I want to save my dataframe in csv file, for that i need to cast the array to string type. I tried to cast it: DF.Filters.tostring() and DF.Filters.cast(StringType()), but both solutions generate error message for each row in the co…
How to verify SqlAlchemy engine object
I can declare engine object with the invalid username, password or address and get no exception or error: it prints likes it is a valid engine object: What would be a common way to verify (to check) if the engine object is valid or if it is “connectable” to db? Answer Question: How to verify if th…
Register temp table in dataframe not working
Below is my script to use sql in dataframe with python: df.show(5) shows result below: then I register the dataframe to a temp table: and tried to run some sql query like below: It doesn’t produce expected result, instead: I also tried: and it gives me: So it seems the registerTempTable method only crea…
How to perform a left join in SQLALchemy?
I have a SQL query which perfroms a series of left joins on a few tables: So far, I have: but I can’t figure out how to make the join a LEFT JOIN. Answer The isouter=True flag will produce a LEFT OUTER JOIN which is the same as a LEFT JOIN. With your code: Declarative example:
Pandas DENSE RANK
I’m dealing with pandas dataframe and have a frame like this: I want to make an equialent to DENSE_RANK () over (order by year) function. to make an additional column like this: How can it be done in pandas? Thanks! Answer Use pd.Series.rank with method=’dense’
‘unicode’ object has no attribute ‘utcoffset’
In my admin, I am getting errors for only one class, ‘unicode’ object has no attribute ‘utcoffset’. I have looked at a few other similar questions and have been unable to solve it. Any ideas on how to fix it? The traceback is below the class. Traceback: Answer The default value for you…
how django ‘auto_now’ ignore the update of specified field
i have a model, like this: name = models.CharField(max_length=255) modify_time = models.DateTimeField(auto_now=True) chasha = models.CharField(max_length=255) stat = models.CharField(…
Add an autoincrementing ID column to an existing table with Sqlite
Using Sqlite, I want to add an auto-incrementing ID column to an existing table which had previously no ID: How to do it properly? I have this error: sqlite3.OperationalError: near “auto_increment”: syntax error Answer An SQLite table cannot modified in a significant manner using alter table once …
Filtering a Pyspark DataFrame with SQL-like IN clause
I want to filter a Pyspark DataFrame with a SQL-like IN clause, as in sc = SparkContext() sqlc = SQLContext(sc) df = sqlc.sql(‘SELECT * from my_df WHERE field1 IN a’) where a is the tuple (1, 2, 3). …