生成准确表达文章主题的标题 使用 SQL 进行选择并更新的正确方法

BEGIN; -- 开启事务
SELECT id, condition, task FROM todos WHERE ... FOR UPDATE;
-- 在这里进行业务逻辑处理
UPDATE todos SET ... WHERE id = ...;
COMMIT; -- 提交事务

package main

import (
    "database/sql"
    "fmt"
    _ "github.com/lib/pq" // 导入 PostgreSQL 驱动
    "log"
)

func main() {
    // 数据库连接信息
    connStr := "user=your_user password=your_password dbname=your_db sslmode=disable"
    db, err := sql.Open("postgres", connStr)
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    // 开启事务
    tx, err := db.Begin()
    if err != nil {
        log.Fatal(err)
    }
    defer func() {
        if p := recover(); p != nil {
            tx.Rollback()
            panic(p) // re-throw panic after Rollback
        } else if err != nil {
            tx.Rollback()
            log.Fatalf("rollback error: %v", err)
        } else {
            err = tx.Commit()
            if err != nil {
                log.Fatal(err)
            }
        }
    }()

    // 查询并锁定需要更新的行
    rows, err := tx.Query("SELECT id, condition, task FROM todos WHERE condition = 0 FOR UPDATE")
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()

    // 遍历结果集并更新数据
    for rows.Next() {
        var id int
        var condition int
        var task string
        err = rows.Scan(&id, &condition, &task)
        if err != nil {
            log.Fatal(err)
        }

        // 更新数据
        newTask := fmt.Sprintf("Updated task for id: %d", id)
        _, err = tx.Exec("UPDATE todos SET task = $1 WHERE id = $2", newTask, id)
        if err != nil {
            log.Fatal(err)
        }
        fmt.Printf("Updated task for id: %d\n", id)
    }

    err = rows.Err()
    if err != nil {
        log.Fatal(err)
    }
    // 提交事务
    // 事务在 defer 语句中已经提交，此处无需重复提交
    fmt.Println("Transaction completed successfully.")
}

UPDATE todos
SET task = 'new task'
FROM (SELECT id FROM todos WHERE condition = 0) AS subquery
WHERE todos.id = subquery.id;