Parsing the correct implementation method for operating Sqlite in Python

The Python programming language has many advantages. Its programming features are mainly reflected in the scalability. In the next article, we will introduce the application skills related to Python-based Sqlite operations in detail, hoping to help you.

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I. Installation

Go to the PySqlite homepage to download the installation package, which has the windows version. Now supports Python 2.3 and 2.5.

2. Create a database/open a database

Python uses a file as a database to operate Sqlite. You can specify the location of the database file.

 
 

  
  
>>> import sqlite3 >>> cx = sqlite.connect("d:/test.db", 
encoding='cp936') 
 
 

You can use sqlite connect to create a database file. The path is specified above. When the database file does not exist, it is automatically created. If the file already exists, open the file. Encoding indicates the encoding used to save the data. cp936 is a self-contained encoding in Python, which is actually GBK encoding. Cx is the database connection object.

III. Basic database objects

3.1 database connection object

Like the preceding cx is a database connection object, it can perform the following operations:

 
 

  
  
Commit () -- transaction commit
  
  
Rollback () -- transaction rollback
  
  
Close () -- close a database connection
  
  
Cursor () -- create a cursor
 
 

3.2 cursor object

All SQL statements must be executed under the cursor object.

 
 

  
  
Cu = cx. cursor () defines a cursor. The cursor object has the following operations:
  
  
Execute () -- execute an SQL statement
  
  
Executemany -- execute multiple SQL statements
  
  
Close () -- close the cursor
  
  
Fetchone () -- get a record from the result
  
  
Fetchrecords () -- retrieve multiple records from the results
  
  
Fetchall () -- retrieve multiple records from the result
  
  
Scroll () -- cursor scroll
 
 

For object methods, go to the Python homepage to view detailed database API documentation. But PySqlite? I don't know what programs support DB APIs. All the operations I listed are supported, but I have not used them all.

Iv. Examples

4.1 database creation

We already have it. We will not repeat it. If you are interested in these examples, you can try it directly in the Python interaction environment)

4.2 create a table

 
 

  
  
>>> cu=cx.cursor() >>> cu.execute("""create table catalog 
( id integer primary key, pid integer, name varchar(10) UNIQUE )""") 
 
 

The preceding statement creates a table named catalog, which has a primary key id, a pid, and a name and name that cannot be repeated.

For the data types supported by Python to operate Sqlite, see Version 2 DataTypes?

4.3 insert)

 
 

  
  
>>> cu.execute("insert into catalog values(0, 0, 'name1')") 
>>> cu.execute("insert into catalog values(1, 0, 'hello')") >>> cx.commit() 
 
 

If you want to, you can always use the cu cursor object. Note that the transaction statement commit () or rollback () must be used to modify the data, and the object is the database connection object. cx is used here.

4.4 select)

 
 

  
  
>>> cu.execute("select * from catalog") >>> cu.fetchall() 
[(0, 0, 'name2'), (1, 0, 'hello')]fetchall()  
 
 

Returns all data in the result set. The result is a tuple list. Each tuple element is arranged in the order of fields in the table creation. Note that a cursor is stateful and records the first few records of the result. Therefore, you can traverse the result set only once. In the preceding case, if fetchone () is executed, null is returned. Note This during testing.

 
 

  
  
>>> cu.execute("select * from catalog where id = 1") 
>>> cu.fetchone() (1, 0, 'hello') 
 
 

If no statement is modified for the database, you do not need to execute the transaction statement after execution.

4.5 update (modify)

 
 

  
  
>>> Cu.exe cute ("update catalog set name = 'name2' where id = 0 ")
>>> Cx. commit () >>> cu.exe cute ("select * from catalog ")
>>> Cu. fetchone () (0, 0, 'name2') 4.6 delete (delete)
  
  
>>> Cu.exe cute ("delete from catalog where id = 1") >>> cx. commit ()
>>> Cu.exe cute ("select * from catalog") >>> cu. fetchall () [(0, 0, 'name2')]
 
 

The above is a simple example of how to use Python to operate Sqlite.