MySQL and PostgreSQL: How to use databases in mobile development?

MySQL and PostgreSQL: How to use databases in mobile development?

With the popularity of mobile devices, the development of mobile applications has become a hot topic. The database plays an important role in mobile applications for storing and managing data. This article will introduce how to use MySQL and PostgreSQL databases in mobile development and give corresponding code examples.

1. MySQL

MySQL is a common relational database management system with a wide range of applications and good performance. To use MySQL in mobile development, we need to first install the MySQL database on the mobile device and introduce the corresponding library files.

1. Install MySQL database

First, we need to download and install the MySQL database. A mobile-friendly version can be downloaded from the official MySQL website. After the installation is complete, remember the username and password for the database for subsequent connections.

2. Introducing MySQL library files

During the construction process of mobile applications, we need to introduce MySQL library files in order to use related APIs for database operations. In Android development, you can introduce the MySQL library by adding the following dependency:

implementation 'mysql:mysql-connector-java:8.0.22'

In iOS development, you can use CocoaPods Introduce the MySQL library:

pod 'MySQL', '~> 8.0'

3. Establish a database connection

In the mobile application, we need to establish Connection to the MySQL database for reading and writing data. In Android development, you can use the following code to establish a connection:

String url = "jdbc:mysql://localhost:3306/database_name";
String username = "root";
String password = "123456";

try {

Connection conn = DriverManager.getConnection(url, username, password);

} catch (SQLException e) {

e.printStackTrace();

}

In iOS development, you can use the following code Establish a connection:

NSURL *url = [NSURL URLWithString:@"mysql://localhost:3306/database_name"];
NSDictionary *options = @{

@"user": @"root",
@"password": @"123456"

};

NSError *error;
PGConnection *conn = [PGConnection connectionWithURL:url options:options error:&error];

4. Database operation

Establish After connecting, we can use the relevant APIs to perform database operations. The following are some commonly used operation examples:

4.1 Data query

String sql = "SELECT * FROM table_name";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);

while (rs.next()) {

int id = rs.getInt("id");
String name = rs.getString("name");
// do something with the data

}

4.2 Data insertion

String sql = " INSERT INTO table_name (name, age) VALUES ('John', 25)";
Statement stmt = conn.createStatement();
stmt.executeUpdate(sql);

4.3 Data update

String sql = "UPDATE table_name SET age = 26 WHERE id = 1";
Statement stmt = conn.createStatement();
stmt.executeUpdate(sql);

4.4 Data deletion

String sql = "DELETE FROM table_name WHERE id = 1";
Statement stmt = conn.createStatement();
stmt.executeUpdate(sql);

二, PostgreSQL

PostgreSQL is another popular relational database management system and a powerful open source database. Using PostgreSQL in mobile development is similar to using MySQL, but you need to pay attention to how different library files are introduced.

1. Install PostgreSQL database

First, we need to download and install the PostgreSQL database. A mobile-friendly version can be downloaded from the official PostgreSQL website. After the installation is complete, remember the username, password and database name for subsequent connections.

2. Introducing PostgreSQL library files

In Android development, you can introduce the PostgreSQL library by adding the following dependencies:

implementation 'org.postgresql:postgresql :42.2.18'

In iOS development, you can use the following code to introduce the PostgreSQL library:

pod 'libpq', '~> 5.1'

3. Establishing a database connection

In the mobile application, we need to establish a connection with the PostgreSQL database. The process is similar to establishing a MySQL connection.

Connection establishment example in Android development:

String url = "jdbc:postgresql://localhost:5432/database_name";
String username = "root";
String password = "123456";

try {

Connection conn = DriverManager.getConnection(url, username, password);

} catch (SQLException e) {

e.printStackTrace();

}

Connection establishment example in iOS development ：

NSURL *url = [NSURL URLWithString:@"postgresql://localhost:5432/database_name"];
NSDictionary *options = @{

@"user": @"root",
@"password": @"123456"

};

NSError *error;
PGConnection *conn = [PGConnection connectionWithURL:url options:options error:&error];

4. Database operation

After establishing the connection , we can use related APIs to perform database operations, similar to MySQL. Here are some examples:

4.1 Data Query

String sql = "SELECT * FROM table_name";
Statement stmt = conn.createStatement();
ResultSet rs = stmt. executeQuery(sql);

while (rs.next()) {

int id = rs.getInt("id");
String name = rs.getString("name");
// do something with the data

}

4.2 Data insertion, update and deletion

Similar to MySQL , use corresponding SQL statements to insert, update and delete data.

3. Summary

This article introduces how to use MySQL and PostgreSQL databases in mobile terminal development, and gives corresponding code examples. No matter which database is used, we can achieve data storage and management by establishing a database connection and using related API operations. I hope readers can learn about the methods of using databases in mobile development through this article, and lay a solid foundation for developing efficient and stable mobile applications.

Note: The above example code is for reference only. In actual development, it needs to be adjusted appropriately according to the specific situation.

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