Python MySQL如何使用select查询（代码示例）

Python数据库API(应用程序接口)是标准Python的数据库接口。大多数Python数据库接口都遵守该标准。 Python数据库支持各种数据库服务器, 例如MySQL, GadFly, mSQL, PostgreSQL, Microsoft SQL Server 2000, Informix, Interbase, Oracle, Sybase等。要从Python与MySQL数据库服务器连接, 我们需要导入mysql.connector模块。
下面是一个与MySQL数据库连接的程序极客.

# importing required library import mysql.connector# connecting to the database dataBase = mysql.connector.connect( host = "localhost" , user = "user" , passwd = "pswrd" , database = "geeks" ) # preparing a cursor object cursorObject = dataBase.cursor() # disconnecting from server dataBase.close()

上面的程序说明了与MySQL数据库的连接极客其中主机名是本地主机, 用户名是用户密码是pswrd.
SELECT查询在MySQL中连接数据库后, 我们可以从其中的表中SELECT查询。
语法如下：
为了从表中选择特定的属性列, 我们编写属性名称。

SELECT attr1, attr2 FROM table_name

为了从表格中选择所有属性列, 我们使用星号" *"。

SELECT * FROM table_name

示例1：让我们考虑一下表格如下所示–

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下面是一个从数据库表中选择查询的程序。

# importing required library import mysql.connector # connecting to the database dataBase = mysql.connector.connect( host = "localhost" , user = "user" , passwd = "pswrd" , database = "geeks" ) # preparing a cursor object cursorObject = dataBase.cursor()print ( "Displaying NAME and ROLL columns from the STUDENT table:" )# selecting query query = "SELECT NAME, ROLL FROM STUDENT" cursorObject.execute(query)myresult = cursorObject.fetchall()for x in myresult: print (x)# disconnecting from server dataBase.close()

输出如下：

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示例2：让我们看另一个在表中选择查询的示例。

# importing required library import mysql.connector # connecting to the database dataBase = mysql.connector.connect( host = "localhost" , user = "user" , passwd = "pswrd" , database = "geeks" )# preparing a cursor object cursorObject = dataBase.cursor()print ( "Displaying NAME and ROLL columns from the STUDENT table:" )# selecting query query = "SELECT * FROM STUDENT" cursorObject.execute(query)myresult = cursorObject.fetchall()for x in myresult: print (x)# disconnecting from server dataBase.close()

输出如下：