如何使用Python更改 SQLite 表？

在本文中，我们将讨论如何使用 sqlite3 模块从Python程序更改 SQLite 数据库中的表。

我们可以通过使用 ALTER 语句来做到这一点。它允许：

• 向表中添加一列或多列

更改表的名称。

向表中添加列

在 SQLite 中的现有表中添加新列的 ALTER TABLE 语法如下：

ALTER TABLE table_name ADD COLUMN column_name colume_type

该列已添加，但所有值都将为 NULL。

要创建表：

Python3

import sqlite3
 
# Connecting to sqlite
connection_obj = sqlite3.connect('geek.db')
 
# cursor object
cursor_obj = connection_obj.cursor()
 
# Drop the GEEK table if already exists.
cursor_obj.execute("DROP TABLE IF EXISTS GEEK")
 
# Creating table
table = """ CREATE TABLE GEEK (
            Email VARCHAR(255) NOT NULL,
            Name CHAR(25) NOT NULL,
            Score INT
        ); """
 
cursor_obj.execute(table)
 
# Inserting data into geek table
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek1",25)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek2",15)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek3",36)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek4",27)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek5",40)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek6",14)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("[e-mail]","Geek7",10)""")
 
# Display table
data = cursor_obj.execute("""SELECT * FROM GEEK""")
print('GEEK Table:')
for row in data:
    print(row)
 
connection_obj.commit()
 
# Close the connection
connection_obj.close()

输出：

现在我们添加一个新列“用户名”：

蟒蛇3

import sqlite3
 
# Connecting to sqlite
connection_obj = sqlite3.connect('geek.db')
 
# cursor object
cursor_obj = connection_obj.cursor()
 
# Add a new column to geek table
new_column = "ALTER TABLE GEEK ADD COLUMN UserName CHAR(25)"
 
cursor_obj.execute(new_column)
 
# Display table
data = cursor_obj.execute("SELECT * FROM GEEK")
print('GEEK Table:')
for row in data:
    print(row)
 
connection_obj.commit()
 
# Close the connection
connection_obj.close()

输出：

更改表名

下面给出了在 SQLite 中更改表名称的 ALTER TABLE 语法：

ALTER TABLE table_name RENAME TO newTableName;

我们将使用我们在上面创建的相同的 GEEK 表：

蟒蛇3

import sqlite3
 
# Connecting to sqlite
connection_obj = sqlite3.connect('geek.db')
 
# cursor object
cursor_obj = connection_obj.cursor()
 
# select from sqlite_master
cursor_obj.execute("SELECT * FROM sqlite_master")
 
table = cursor_obj.fetchall()
print("Before changing the name of Table")
print("The name of the table:", table[0][2])
 
# Rename the SQLite Table
renameTable = "ALTER TABLE GEEK RENAME TO GFG"
cursor_obj.execute(renameTable)
 
 
# select from sqlite_master
cursor_obj.execute("SELECT * FROM sqlite_master")
 
table = cursor_obj.fetchall()
 
print("After changing the name of Table")
print("The name of the table:", table[0][2])
 
connection_obj.commit()
 
connection_obj.close()

输出：