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2022/2/21

Golang sql PostgreSQL新增範例

Go程式新增一筆資料到PostgreSQL資料庫範例如下。


範例環境:

  • Go 1.17
  • PostgreSQL 14

PostgreSQL的postgres資料庫的employee資料表如下。

CREATE TABLE IF NOT EXISTS employee (
   id bigserial PRIMARY KEY,
   name varchar(60) UNIQUE NOT NULL,
   age integer,
   created_at timestamp NOT NULL
);

在專案根目錄執行go get github.com/lib/pq下載driver。

~/../go-demo$ go get github.com/lib/pq

下面程式連線到PostgresSQL資料庫並新增一筆資料至employee資料表並回傳idRETURNING用來返回INSERT後自動產生的id序號。

CreateEmployee()中調用sql.Tx.QueryRow()執行新增SQL並帶入參數,接著調用Row.Scan()讀取id欄位值返回。

sql.DB.Begin()sql.Tx.Rollback()sql.Tx.Commit()交易/事務管理範圍。

main.go

package main

import (
    "database/sql"
    "fmt"
    "time"

    _ "github.com/lib/pq"
)

type Employee struct {
    ID        int64
    Name      string
    Age       int
    CreatedAt time.Time
}

const (
    HOST     = "localhost"
    PORT     = "5432"
    DATABASE = "postgres"
    USER     = "admin"
    PASSWORD = "12345"
    SSL      = "disable"
)

func connect() *sql.DB {
    driver := "postgres"
    dsn := fmt.Sprintf(
        "host=%s port=%s user=%s password=%s dbname=%s sslmode=%s",
        HOST, PORT, USER, PASSWORD, DATABASE, SSL)

    db, err := sql.Open(driver, dsn)
    if err != nil {
        panic("open database error")
    }
    return db
}

func main() {
    db := connect()
    emp := Employee{
        Name: "tony",
        Age:  23,
    }
    id, err := CreateEmployee(db, &emp)
    if err != nil {
        panic(err)
    }
    fmt.Println(id)
}

func CreateEmployee(db *sql.DB, emp *Employee) (int64, error) {
    tx, err := db.Begin()
    if err != nil {
        return 0, err
    }
    defer tx.Rollback()

    id := int64(0)
    query := `INSERT INTO employee (name, age, created_at) 
            VALUES ($1, $2, $3) 
            RETURNING id`

    err = tx.QueryRow(query, &emp.Name, &emp.Age, time.Now()).Scan(&id)
    if err != nil {
        return 0, err
    }

    if err = tx.Commit(); err != nil {
        return 0, err
    }

    return id, nil
}

github


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