I would like to create a MySQL table with Pandas’ to_sql function which has a primary key (it is usually kind of good to have a primary key in a mysql table) as so:

Instead you can use a single key and, as value, a list of elements that had that key. So you can follow these steps: See if the current element's (of your initial set) key is in the final dict. If it is, go to step 3. Update dict with key. Append the new value to the dictkey list. This module provides immutable UUID objects (the UUID class) and the functions uuid1, uuid3, uuid4, uuid5 for generating version 1, 3, 4, and 5 UUIDs as specified in RFC 4122. If all you want is a unique ID, you should probably call uuid1 or uuid4.Note that uuid1 may compromise privacy since it creates a UUID containing the computer’s network address. While there are many sophisticated ways to generate these, in many cases it is perfectly adequate to use sufficiently long and random sequences of characters. The problem is that if you are doing this in Python, there is more than one way to generate random strings, and it isn't always clear which way is the best and most secure. Introduction to the MySQL UNIQUE index. To enforce the uniqueness value of one or more columns, you often use the PRIMARY KEY constraint. However, each table can have only one primary key. Hence, if you want to have a more than one column or a set of columns with unique values, you cannot use the primary key constraint.

but this creates a table without any primary key, (or even without any index).

Jan 31, 2018  but this creates a table without any primary key, (or even without any index). The documentation mentions the parameter indellabel which could be used to create an index but doesn’t mention any option for primary keys.

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The documentation mentions the parameter indel_label which could be used to create an index but doesn’t mention any option for primary keys.

Answers:

Disclaimer: this answer is more experimental then practical, but maybe worth mention.

I found that class pandas.io.sql.SQLTable has named argument key and if you assign it the name of the field then this field becomes the primary key:

Unfortunately you can’t just transfer this argument from DataFrame.to_sql() function. To use it you should:

  1. create pandas.io.SQLDatabase instance

  2. define function analoguous to pandas.io.SQLDatabase.to_sql() but with additional *kwargs argument which is passed to pandas.io.SQLTable object created inside it (i’ve just copied original to_sql() method and added *kwargs):

  3. call this function with your SQLDatabase instance and the dataframe you want to save

And we get something like

in the database.

PS You can of course monkey-patch DataFrame, io.SQLDatabase and io.to_sql() functions to use this workaround with convenience.

Answers:

Simply add the primary key after uploading the table with pandas.

Answers:

automap_base from sqlalchemy.ext.automap (tableNamesDict is a dict with only the Pandas tables):

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Which would have worked perfectly, except for one problem, automap requires the tables to have a primary key. Ok, no problem, I’m sure Pandas to_sql has a way to indicate the primary key… nope. This is where it gets a little hacky:

I iterate thru the dict of DataFrames, get a list of the columns to use for the primary key (i.e. those containing id), use get_schema to create the empty tables then append the DataFrame to the table.

Python Generate Unique Key

Now that you have the models, you can explicitly name and use them (i.e. User = Base.classes.user) with session.query or create a dict of all the classes with something like this:

Java key code Jun 18, 2014  In Java generating public private key using RSA algorithm is quite easy as it provides lib to do these tasks. In Java java.security package contains classes to do these operation. Generating public private key pairs. By using KeyPairGenerator class we can generate public/private key. In this example you will generate a public/private key pair for the Digital Signature Algorithm (DSA). You will generate keys with a 1024-bit length. Generating a key pair requires several steps: Create a Key Pair Generator. The first step is to get a key-pair generator object for generating keys. Generate a private-public key pair using keytool. Protect your existing private rsa key with a passphrase. Save/Load Private and Public Key to/from a file / Published in: Java. Save to your folder(s) Save/Load. Store/Retrieve Private Key/Public Key to/from disk/file:D. Expand Embed Plain Text. Copy this code. Assuming the key is an RSA key, and it's stored in a standard way, the 'private key' as meant by the library (openssl) includes the public key. It's not about 'generating' but more about 'extracting'/'accessing'. Nov 01, 2018  A private key can be use to sign a document and the public key is use to verify that the signature of the document is valid. The API we use to generate the key pairs is in the java.security package. That’s mean we have to import this package into our code. The class for generating the key pairs is KeyPairGenerator.

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And query with:

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Tags: pandas, python, sql