MySQL学习之go-mysql

1.安装和导入

首先需要安装数据库驱动：

go get -u github.com/go-sql-driver/mysql
go get -u github.com/lib/pq

导入需要的包

import (
	"databse/sql"
	"fmt"
	"log"
	_ "github.com/go-sql-driver/mysql"
)

2.连接数据库

func main(){
	db,err :=sql.Open("msyql","username:password@tcp(127.0.0.1:3306)/dbname")
	if err != nil {
		lgo.Fatal(err)
	}
	defer db.Close()
	err = db.Ping()
	if err != nil {
		log.Fatel(err)
	}
	fmt.Println("数据库连接成功")
}

3.基础CRUD操作

1. 创建表

func createTable(db *sql.DB)error{
	query := `
			CREATE TABLE IF NOT EXSTS users(
				id INT AUTO_INCREAMENT PRIMARY KEY,
				name VARCHAR(100) NOT NULL,
				email VARCAHR(100) UNIQUE NOT NULL,
				age 	INT,
				created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
			)
	`_,err  db.Exec(query)
	return err
}

2. 插入数据

func insertUser(db *sql.DB, name, email string, age int) (int64, error) {
    result, err := db.Exec(
        "INSERT INTO users (name, email, age) VALUES (?, ?, ?)",
        name, email, age,
    )
    if err != nil {
        return 0, err
    }
    
    id, err := result.LastInsertId()
    return id, err
}

3. 查询数据

type User struct {
    ID        int
    Name      string
    Email     string
    Age       int
    CreatedAt string
}

// 查询单个用户
func getUser(db *sql.DB, id int) (*User, error) {
    var user User
    err := db.QueryRow(
        "SELECT id, name, email, age, created_at FROM users WHERE id = ?", 
        id,
    ).Scan(&user.ID, &user.Name, &user.Email, &user.Age, &user.CreatedAt)
    
    if err != nil {
        return nil, err
    }
    return &user, nil
}

// 查询多个用户
func getUsers(db *sql.DB) ([]User, error) {
    rows, err := db.Query("SELECT id, name, email, age, created_at FROM users")
    if err != nil {
        return nil, err
    }
    defer rows.Close()
    
    var users []User
    for rows.Next() {
        var user User
        err := rows.Scan(&user.ID, &user.Name, &user.Email, &user.Age, &user.CreatedAt)
        if err != nil {
            return nil, err
        }
        users = append(users, user)
    }
    
    return users, nil
}

4. 更新数据

func updateUser(db *sql.DB, id int, name, email string, age int) error {
    _, err := db.Exec(
        "UPDATE users SET name = ?, email = ?, age = ? WHERE id = ?",
        name, email, age, id,
    )
    return err
}

5.删除数据

func deleteUser(db *sql.DB, id int) error {
    _, err := db.Exec("DELETE FROM users WHERE id = ?", id)
    return err
}

4.预处理语句

func batchInsertUsers(db *sql.DB,users []User)error{
	stmt,err :=db.Prepare("INSERT INTO users (name, email, age) VALUES (?, ?, ?)")
	if err != nil {
		return err
	}
	defer stmt.Close()
    
    for _, user := range users {
        _, err := stmt.Exec(user.Name, user.Email, user.Age)
        if err != nil {
            return err
        }
    }
    return nil
}

5.事务处理

func transferMoney(db *sql.DB, fromID, toID int, amount float64) error {
    tx, err := db.Begin()
    if err != nil {
        return err
    }
    
    // 执行转账操作
    _, err = tx.Exec("UPDATE accounts SET balance = balance - ? WHERE id = ?", amount, fromID)
    if err != nil {
        tx.Rollback()
        return err
    }
    
    _, err = tx.Exec("UPDATE accounts SET balance = balance + ? WHERE id = ?", amount, toID)
    if err != nil {
        tx.Rollback()
        return err
    }
    
    return tx.Commit()
}

6.连接吃配置

func initDB() *sql.DB {
    db, err := sql.Open("mysql", "user:pass@tcp(localhost:3306)/dbname")
    if err != nil {
        log.Fatal(err)
    }
    
    // 配置连接池
    db.SetMaxOpenConns(25)      // 最大打开连接数
    db.SetMaxIdleConns(10)      // 最大空闲连接数
    db.SetConnMaxLifetime(5 * time.Minute)  // 连接最大生存时间
    
    return db
}

总结

1. sql.Open() 只创建连接对象，不实际连接数据库

2. db.Ping() 用于验证连接

3. db.Exec() 用于执行不返回行的操作

4. db.Query() 用于查询多行数据

5. db.QueryRow() 用于查询单行数据

6. 使用 预处理语句 提高性能和安全性

7. 记得 defer rows.Close() 和 defer stmt.Close()

8. 使用 事务 保证数据一致性

9. 合理配置 连接池 参数