MySQL is an excellent, very popular and open source database management system. A binary installation is available for Mac OS, and the process of installing MySQL on Mac OS is also very well documented. So just head over to MySQL.com, where you will find the binary installation, together with extensive installation, and usage documentation.
To connect to MySQL from Python use MySQL for Python (MySQLdb). Get MySQLdb from http://sourceforge.net/projects/mysql-python/.
- Download MySQL from mysql.com and install the DBMS as instructed in the documentation.
- Make sure “Library/Python/2.3” does not have:
After spending an considerable amount of time installing MySQLdb on Mac OS X 10.5 Leopard, I had to repeat a similar exercise today. I am no expert at this kind of thing whatsoever. Still, I thought it might be useful to share my experiences with you. I let Snow Leopard (NY Times review) in into my house last friday (August 28th, 2009) and the upgrade process (from Leopard) went really smoothly. For most Unix systems, you must download and compile the source code. The same source code archive can also be used to build the Windows and Mac versions, and is the starting point for ports to all other platforms. Download the latest Python 3 and Python 2 source. Setting up MySQL for Python (MySQLdb) on Mac OS X Posted: November 16, 2007 Author: J du Preez Filed under: DataBase, Python Tags: Apple, Data Access, Mac Dev, Mac OS X, MySQL, MySQL for Python, Python 4 Comments MySQL is an excellent, very popular and open source database management system. A binary installation is available for Mac OS, and the process of installing MySQL on Mac OS is. Sudo apt-get install python-pip python-dev libmysqlclient-dev Fedora 24: sudo dnf install python python-devel mysql-devel redhat-rpm-config gcc Mac OS brew install mysql-connector-c if that fails, try. Brew install mysql. Installing MySQL, Python, MySQLdb on Snow Leopard (Mac OS X 10.6) for Django After spending an considerable amount of time installing MySQLdb on Mac OS X 10.5 Leopard, I had to repeat a similar exercise today.
- Directory “MySQL”
- File “_mysql.pyd”
- File “_mysql_exceptions.py”
- File “_mysql_exceptions.pyc”
Either uninstall MySQL for Python if a setup program was used to install it, otherwise manually delete them.
- Download and unpack MySQL for Python. At the time of writing this is MySQL-python-1.2.1_p2.tar.gz .
- Open Terminal and change to the directory where MySQLdb was unpacked to.
- Get rid of any previous builds that might interfere, by deleting the “build” directory if it exists.
- Edit the setup.py file, and change:
return popen(“mysql_config –%s” % what)
to
return popen(“/usr/local/mysql/bin/mysql_config –%s” % what) - Cleanup any previous install attempts:
python setup.py clean
- Build MySQLdb:
python setup.py build
Viola! MySQL for Python is all setup, and ready for your Python-MySQL data access code. Enjoy!
- Python Basic Tutorial
- Python Advanced Tutorial
- Python Useful Resources
- Selected Reading
The Python standard for database interfaces is the Python DB-API. Most Python database interfaces adhere to this standard.
You can choose the right database for your application. Python Database API supports a wide range of database servers such as −
- GadFly
- mSQL
- MySQL
- PostgreSQL
- Microsoft SQL Server 2000
- Informix
- Interbase
- Oracle
- Sybase
Here is the list of available Python database interfaces: Python Database Interfaces and APIs. You must download a separate DB API module for each database you need to access. For example, if you need to access an Oracle database as well as a MySQL database, you must download both the Oracle and the MySQL database modules.
The DB API provides a minimal standard for working with databases using Python structures and syntax wherever possible. This API includes the following −
- Importing the API module.
- Acquiring a connection with the database.
- Issuing SQL statements and stored procedures.
- Closing the connection
We would learn all the concepts using MySQL, so let us talk about MySQLdb module.
What is MySQLdb?
MySQLdb is an interface for connecting to a MySQL database server from Python. It implements the Python Database API v2.0 and is built on top of the MySQL C API.
How do I Install MySQLdb?
Before proceeding, you make sure you have MySQLdb installed on your machine. Just type the following in your Python script and execute it −
If it produces the following result, then it means MySQLdb module is not installed −
To install MySQLdb module, use the following command −
Note − Make sure you have root privilege to install above module.
Database Connection
Before connecting to a MySQL database, make sure of the followings −
You have created a database TESTDB.
You have created a table EMPLOYEE in TESTDB.
This table has fields FIRST_NAME, LAST_NAME, AGE, SEX and INCOME.
User ID 'testuser' and password 'test123' are set to access TESTDB.
Python module MySQLdb is installed properly on your machine.
You have gone through MySQL tutorial to understand MySQL Basics.
Example
Following is the example of connecting with MySQL database 'TESTDB'
While running this script, it is producing the following result in my Linux machine.
If a connection is established with the datasource, then a Connection Object is returned and saved into db for further use, otherwise db is set to None. Next, db object is used to create a cursor object, which in turn is used to execute SQL queries. Finally, before coming out, it ensures that database connection is closed and resources are released.
Creating Database Table
Once a database connection is established, we are ready to create tables or records into the database tables using execute method of the created cursor.
Example
Let us create Database table EMPLOYEE −
INSERT Operation
It is required when you want to create your records into a database table.
Example
The following example, executes SQL INSERT statement to create a record into EMPLOYEE table −
Python Mysqldb For Mac Installer
Above example can be written as follows to create SQL queries dynamically −
Example
Following code segment is another form of execution where you can pass parameters directly −
READ Operation
READ Operation on any database means to fetch some useful information from the database.
Once our database connection is established, you are ready to make a query into this database. You can use either fetchone() method to fetch single record or fetchall() method to fetech multiple values from a database table.
fetchone() − It fetches the next row of a query result set. A result set is an object that is returned when a cursor object is used to query a table.
fetchall() − It fetches all the rows in a result set. If some rows have already been extracted from the result set, then it retrievesthe remaining rows from the result set.
rowcount − This is a read-only attribute and returns the number of rows that were affected by an execute() method.
Example
The following procedure queries all the records from EMPLOYEE table having salary more than 1000 −
This will produce the following result −
Update Operation
UPDATE Operation on any database means to update one or more records, which are already available in the database.
The following procedure updates all the records having SEX as 'M'. Here, we increase AGE of all the males by one year.
Example
DELETE Operation
DELETE operation is required when you want to delete some records from your database. Following is the procedure to delete all the records from EMPLOYEE where AGE is more than 20 −
Example
Performing Transactions
Transactions are a mechanism that ensures data consistency. Transactions have the following four properties −
Atomicity − Either a transaction completes or nothing happens at all.
Consistency − A transaction must start in a consistent state and leave the system in a consistent state.
Isolation − Intermediate results of a transaction are not visible outside the current transaction.
Durability − Once a transaction was committed, the effects are persistent, even after a system failure.
The Python DB API 2.0 provides two methods to either commit or rollback a transaction.
Example
You already know how to implement transactions. Here is again similar example −
COMMIT Operation
Commit is the operation, which gives a green signal to database to finalize the changes, and after this operation, no change can be reverted back.
Here is a simple example to call commit method.
ROLLBACK Operation
If you are not satisfied with one or more of the changes and you want to revert back those changes completely, then use rollback() method.
Here is a simple example to call rollback() method.
Disconnecting Database
To disconnect Database connection, use close() method.
If the connection to a database is closed by the user with the close() method, any outstanding transactions are rolled back by the DB. However, instead of depending on any of DB lower level implementation details, your application would be better off calling commit or rollback explicitly.
Handling Errors
There are many sources of errors. A few examples are a syntax error in an executed SQL statement, a connection failure, or calling the fetch method for an already canceled or finished statement handle.
The DB API defines a number of errors that must exist in each database module. The following table lists these exceptions.
| Sr.No. | Exception & Description |
|---|---|
| 1 | Warning Used for non-fatal issues. Must subclass StandardError. |
| 2 | Error Base class for errors. Must subclass StandardError. |
| 3 | InterfaceError Used for errors in the database module, not the database itself. Must subclass Error. |
| 4 | DatabaseError Used for errors in the database. Must subclass Error. |
| 5 | DataError Subclass of DatabaseError that refers to errors in the data. |
| 6 | OperationalError Subclass of DatabaseError that refers to errors such as the loss of a connection to the database. These errors are generally outside of the control of the Python scripter. |
| 7 | IntegrityError Subclass of DatabaseError for situations that would damage the relational integrity, such as uniqueness constraints or foreign keys. |
| 8 | InternalError Subclass of DatabaseError that refers to errors internal to the database module, such as a cursor no longer being active. |
| 9 | ProgrammingError Subclass of DatabaseError that refers to errors such as a bad table name and other things that can safely be blamed on you. |
| 10 | NotSupportedError Subclass of DatabaseError that refers to trying to call unsupported functionality. |
Python Mysqldb Connect
Your Python scripts should handle these errors, but before using any of the above exceptions, make sure your MySQLdb has support for that exception. You can get more information about them by reading the DB API 2.0 specification.