Development using MySQL and Go language: How to implement data filtering function

Using MySQL and Go language development: How to implement the data filtering function

1. Introduction
When developing web applications, the data filtering function is a common requirement. We often need to obtain specific data from the database to satisfy the user's search criteria. This article will introduce how to use MySQL and Go language development to implement data filtering functions.

2. Preparation
Before we start, we need to prepare the following environment and tools:

1. Install the MySQL database and create a database and data table;
2. Install the Go language environment;
3. Install the Go MySQL driver package. You can use the "go get" command to install it. The command is: go get github.com/go-sql-driver/mysql

3. Connect to the database
First, we need to connect in the Go program to the MySQL database. You can create a file named "database.go" and add the following code in it:

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/go-sql-driver/mysql"
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(127.0.0.1:3306)/database")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    err = db.Ping()
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println("Connected to MySQL database!")

    // 在这里写入数据筛选的代码
}

Please replace "user", "password" and "database" with your own MySQL username and password and database name.

4. Implement the data filtering function
Next, we will implement the data filtering function in the above code. Suppose we have a data table named "users" which contains three fields: "id", "name" and "age". We want to filter data based on user-specified conditions.

The following is an example of data filtering code, which can obtain user data that meets the conditions based on user input:

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/go-sql-driver/mysql"
)

type User struct {
    ID   int
    Name string
    Age  int
}

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(127.0.0.1:3306)/database")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    err = db.Ping()
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println("Connected to MySQL database!")

    // 数据筛选
    rows, err := db.Query("SELECT id, name, age FROM users WHERE age > ?", 18)
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()

    var users []User

    for rows.Next() {
        var user User
        err := rows.Scan(&user.ID, &user.Name, &user.Age)
        if err != nil {
            log.Fatal(err)
        }

        users = append(users, user)
    }

    err = rows.Err()
    if err != nil {
        log.Fatal(err)
    }

    for _, user := range users {
        fmt.Println(user)
    }
}

In the above code, we use the "db.Query" method to execute Create a SQL query statement to retrieve records that meet the condition (age>18). Then, we use the "rows.Scan" method to read the query results into the User structure, and finally print out the user data that meets the conditions.

5. Summary
Through the introduction of this article, we have learned how to use MySQL and Go language to develop data filtering functions. We connected to the MySQL database and wrote code to implement data filtering. This is just a simple example. In actual development, we can design more complex data filtering functions according to specific needs.

6. Reference materials

1. Go MySQL driver: https://github.com/go-sql-driver/mysql
2. MySQL official documentation: https: //dev.mysql.com/doc/
3. Go language official documentation: https://golang.org/doc/

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