Getting Started with Go Language: Basic Concepts of Database Connections

Learning Go language: basic knowledge of connecting to database, specific code examples are required

Go语言是一种开源的编程语言，其简洁、高效的特性让越来越多的开发者喜爱和使用。在开发过程中，经常需要与数据库建立连接，进行数据的读取、写入、更新和删除等操作。因此，学会如何在Go语言中连接数据库是非常重要的技能。

1. Database driver
   In Go language, connect The database requires the use of a database driver. Currently, the main database drivers of the Go language are as follows:

   • database/sql: It is the database driver interface provided in the Go language standard package and supports a variety of databases, such as MySQL, PostgreSQL, SQLite, etc. .
   • go-sqlite3: is the driver for SQLite database, used to connect and operate SQLite database.
   • pq: is the driver for the PostgreSQL database, used to connect and operate the PostgreSQL database.
   • go-mysql-driver: It is the driver for MySQL database, used to connect and operate MySQL database.

   In this article, we take the MySQL database as an example to explain.

2. Install database driver
   Before using go-mysql-driver to connect to the MySQL database, you need to install the driver first. You can use the following command to install:

   go get github.com/go-sql-driver/mysql

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   After the installation is complete, you can import the package in the Go program and use the functions and structures in it.

3. Connecting to the database
   In the Go language, the steps to connect to the MySQL database are as follows:

   • Import the database driver package: use in the code The import keyword imports the "go-sql-driver/mysql" package.
   • Use the sql.Open() function to open the database connection. The parameters of this function are the driver name and connection string of the database. For example, sql.Open("mysql", "Username: Password@tcp(localhost:3306)/database name").
   • Call the Ping() method of database connection to determine whether the connection is successful, that is, whether the database can be successfully connected.

   The following is a sample code:

   package main
   
   import (
       "database/sql"
       "fmt"
   
       _ "github.com/go-sql-driver/mysql"
   )
   
   func main() {
       // 打开数据库连接
       db, err := sql.Open("mysql", "用户名:密码@tcp(localhost:3306)/数据库名称")
       if err != nil {
           fmt.Println("数据库连接失败：", err)
           return
       }
       defer db.Close()
   
       // 测试连接
       err = db.Ping()
       if err != nil {
           fmt.Println("连接失败：", err)
           return
       }
   
       fmt.Println("连接成功！")
   }

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4. Query data
   After the connection is successful, database operations can be performed. The following is a sample code for querying data:

   rows, err := db.Query("SELECT * FROM table_name")
   if err != nil {
       fmt.Println("查询失败：", err)
       return
   }
   defer rows.Close()
   
   for rows.Next() {
       var id int
       var name string
       err := rows.Scan(&id, &name)
       if err != nil {
           fmt.Println("扫描行失败：", err)
           return
       }
       fmt.Println("ID:", id, "Name:", name)
   }
   
   if err = rows.Err(); err != nil {
       fmt.Println("遍历结果集失败：", err)
       return
   }

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   The above code queries the data in the database through the db.Query() method, and then uses rows.Next() Loop through the query results. Inside the loop, row data is scanned through the rows.Scan() method and the results are stored in variables.

5. Insert data
   In addition to querying data, the Go language can also insert data into the database through the db.Exec() method. The following is a sample code for inserting data:

   result, err := db.Exec("INSERT INTO table_name (name) VALUES (?)", "John")
   if err != nil {
       fmt.Println("插入数据失败：", err)
       return
   }
   
   affectedRows, _ := result.RowsAffected()
   fmt.Println("插入成功，影响的行数为：", affectedRows)

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   Execute the SQL insert statement through the db.Exec() method, where ? represents the parameter placeholder, which can be used Replace with a specific value, such as "John".

6. Updating and deleting data
   In Go language, you can use the db.Exec() method to update and delete data in the database. The following is a sample code for updating data:

   result, err := db.Exec("UPDATE table_name SET name = ? WHERE id = ?", "Tom", 1)
   if err != nil {
       fmt.Println("更新数据失败：", err)
       return
   }
   
   affectedRows, _ := result.RowsAffected()
   fmt.Println("更新成功，影响的行数为：", affectedRows)

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   Execute the SQL update statement through the db.Exec() method, where ? represents the parameter placeholder, which can be used Replace with specific values.

   Similarly, you can use the db.Exec() method to execute SQL delete statements, for example:

   result, err := db.Exec("DELETE FROM table_name WHERE id = ?", 1)

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   The above code deletes table_nameThe id in the table is 1 data.

   Through the introduction of this article, I believe that readers have basically understood the basic knowledge of connecting to databases in Go language. Database operation is a skill that is often used in actual development. I hope the content of this article can be helpful to readers and apply it in actual projects.

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