Master the practical application scenarios of rowcount function

To master the actual application scenarios of the rowcount function, specific code examples are required

In database operations, it is often necessary to add, delete, modify, and query data. For query operations, we often need to get the number of rows in the returned results. At this time, you can use the rowcount function in the database.

The rowcount function is a database operation method used to return the number of record rows affected by the previous executed SQL statement. It can return an integer value representing the number of rows that were modified, inserted, or deleted.

Below, we will introduce common application scenarios of the rowcount function based on actual code examples.

Scenario 1: Data update operation

Suppose we have a student table (student), which contains basic information of students, such as student number (id), name (name) and age (age) ). Now, we want to update the age in the student information to increase the age of all students by 1 year.

First, we need to connect to the database and build a database cursor. Then, execute a SQL statement to update the age field in the student table. The code is as follows:

import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', port=3306, user='root', passwd='123456', db='test')

# 构建数据库游标
cur = conn.cursor()

# 更新学生年龄
sql = "UPDATE student SET age = age + 1"

# 执行SQL语句
cur.execute(sql)

# 获取更新的行数
row_count = cur.rowcount

# 提交事务
conn.commit()

# 关闭游标和连接
cur.close()
conn.close()

# 打印更新的行数
print(f"成功更新了{row_count}条记录")

In the above code, we execute an UPDATE statement to increment the age field in the student table by 1. When executing the cur.rowcount statement, the row_count variable gets the updated row count. Finally, we print out the updated row count to confirm that the operation was successful.

Scenario 2: Data deletion operation

Suppose we need to delete student records older than 20 years old in the student table (student).

First, connect to the database and build a database cursor. Then, execute a SQL statement to delete records that meet the conditions in the student table. The code is as follows:

import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', port=3306, user='root', passwd='123456', db='test')

# 构建数据库游标
cur = conn.cursor()

# 删除年龄大于20岁的学生记录
sql = "DELETE FROM student WHERE age > 20"

# 执行SQL语句
cur.execute(sql)

# 获取删除的行数
row_count = cur.rowcount

# 提交事务
conn.commit()

# 关闭游标和连接
cur.close()
conn.close()

# 打印删除的行数
print(f"成功删除了{row_count}条记录")

In the above code, we execute a DELETE statement to delete records in the student table that are older than 20 years old. Through the cur.rowcount statement, we obtain the number of successfully deleted rows and print them out.

Summary:

The rowcount function has important application value in database operations. It can help us accurately obtain the number of record rows affected by addition, deletion and modification operations, thus facilitating our data processing and monitoring. In the above code example, we show two common application scenarios of the rowcount function: data update and data deletion. Through these examples, we can better understand and master the practical application of the rowcount function. I hope this article can provide some help to readers when using the rowcount function in database operations.

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