使用 golang 准备语句的原始 sql 事务

Question

我找不到一些执行以下三项操作的示例：

1) 在 golang 中允许原始 sql 事务。

2) 使用准备好的语句。

3) 查询失败回滚。

我想做这样的事情，但要使用准备好的语句。

    stmt, stmt_err := db.Prepare(`
            BEGIN TRANSACTION;

            -- Insert record into first table.

            INSERT INTO table_1 (
                    thing_1,
                    whatever)
            VALUES(,);

            -- Inert record into second table.

            INSERT INTO table_2 (
                    thing_2,
                    whatever)
            VALUES(,);

            END TRANSACTION;
            `)
    if stmt_err != nil {
            return stmt_err
    }   
    res, res_err := stmt.Exec(
            thing_1,
            whatever,
            thing_2,
            whatever)

当我运行这个时，我得到这个错误： pq: cannot insert multiple commands into a prepared statement

什么给？在 golang 中甚至可以进行符合 ACID 的事务吗？我找不到例子。

编辑没有例子 here.

Answer 1

是的，Go 有一个很好的实现 sql transactions. We start the transaction with db.Begin and we can end it with tx.Commit if everything goes good or with tx.Rollback 以防出错。

type Tx struct { }

Tx is an in-progress database transaction.

A transaction must end with a call to Commit or Rollback.

After a call to Commit or Rollback, all operations on the transaction fail with ErrTxDone.

The statements prepared for a transaction by calling the transaction's Prepare or Stmt methods are closed by the call to Commit or Rollback.

另请注意，我们使用交易变量 tx.Prepare(...)

准备查询

您的函数可能如下所示：

func doubleInsert(db *sql.DB) error {

    tx, err := db.Begin()
    if err != nil {
        return err
    }

    {
        stmt, err := tx.Prepare(`INSERT INTO table_1 (thing_1, whatever)
                     VALUES(,);`)
        if err != nil {
            tx.Rollback()
            return err
        }
        defer stmt.Close()

        if _, err := stmt.Exec(thing_1, whatever); err != nil {
            tx.Rollback() // return an error too, we may want to wrap them
            return err
        }
    }

    {
        stmt, err := tx.Prepare(`INSERT INTO table_2 (thing_2, whatever)
                     VALUES(, );`)
        if err != nil {
            tx.Rollback()
            return err
        }
        defer stmt.Close()

        if _, err := stmt.Exec(thing_2, whatever); err != nil {
            tx.Rollback() // return an error too, we may want to wrap them
            return err
        }
    }

    return tx.Commit()
}

我有一个完整的例子here

Answer 2

我想出了一个可能的解决方案来回滚任何失败而没有任何重大缺陷。虽然我对 Golang 很陌生，但我可能是错的。

func CloseTransaction(tx *sql.Tx, commit *bool) {
  if *commit {
    log.Println("Commit sql transaction")
    if err := tx.Commit(); err != nil {
      log.Panic(err)
    }
  } else {
    log.Println("Rollback sql transcation")
    if err := tx.Rollback(); err != nil {
      log.Panic(err)
    }
  }
}

func MultipleSqlQuriesWithTx(db *sql.DB, .. /* some parameter(s) */)  (.. .. /* some named return parameter(s) */, err error) {
  tx, err := db.Begin()
  if err != nil {
    return
  }
  commitTx := false
  defer CloseTransaction(tx, &commitTx)

  // First sql query
  stmt, err := tx.Prepare(..) // some raw sql
  if err != nil {
    return
  }
  defer stmt.Close()

  res, err := stmt.Exec(..) // some var args
  if err != nil {
    return
  }

  // Second sql query
  stmt, err := tx.Prepare(..) // some raw sql
  if err != nil {
    return
  }
  defer stmt.Close()

  res, err := stmt.Exec(..) // some var args
  if err != nil {
    return
  }

  /*
    more tx sql statements and queries here
  */

  // success, commit and return result
  commitTx = true
  return
}

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