Go语言sqlx库操作PostgreSQL数据库增删改查

0. 引用

sqlx地址:https://github.com/jmoiron/sqlx
PostgreSQL官网:https://www.postgresql.org/

1. PostgreSQL安装、运行

可以到官网下载二进制包 https://www.postgresql.org/download/
也可以用apt、源代码或者WAPP、LAPP等方式安装

由于docker更方便，直接用docker安装运行
创建数据存放的目录

mkdir /data
mkdir /data/postgres

运行PostgreSQL

docker run -it --name postgres --restart always -e POSTGRES_PASSWORD='admin123' -e ALLOW_IP_RANGE=0.0.0.0/0 -v /data/postgres:/var/lib/postgresql -p 54321:5432 -d postgres

• -e POSTGRES_PASSWORD='abc123' 设置密码为admin123
• -e ALLOW_IP_RANGE=0.0.0.0/0 所有ip可以连接
• -v /data/postgres:/var/lib/postgresql 数据存在本地/data/postgres
• -p 54321:5432 指定端口为54321

PgAdmin4连接测试

2. Go连接数据库

最主要是设置dsn, host设置为数据库ip或域名，port为端口默认5432，我这里用54321，user是postgres ，password是刚才设置的admin123 ，dbname根据需求设置

package main

import (
	"fmt"

	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq"
)

var db *sqlx.DB

func initDB() (err error) {
    
    
	dsn := "host=X.X.X.X port=54321 user=postgres password=admin123 dbname=postgres sslmode=disable"
	db, err := sqlx.Connect("postgres", dsn)
	if err != nil {
    
    
		fmt.Printf("connect DB failed, err:%v\n", err)
		return
	}
	db.SetMaxOpenConns(50)
	db.SetMaxIdleConns(5)
	return
}

func main() {
    
    
	err := initDB()
	if err != nil {
    
    
		return
	}
	fmt.Println("DB Connected...")
}

3. 建立测试用的库和表

新建一个数据库test用于测试

CREATE DATABASE "test"
WITH
  ENCODING = 'UTF8'
;

再建一个表user_info

CREATE TABLE "public"."user_info" (
  "id" serial4,
  "uid" int8 NOT NULL,
  "name" varchar(255) NOT NULL,
  "group" varchar(255) NOT NULL,
  "balance" decimal(8,2) NOT NULL,
  "proportion" float8 NOT NULL,
  "create_time" timestamp NOT NULL,
  "comments" varchar(255),
  PRIMARY KEY ("id")
);

CREATE INDEX "indexs" ON "public"."user_info" USING btree (
  "name",
  "group"
);

CREATE UNIQUE INDEX "uniques" ON "public"."user_info" USING btree (
  "uid"
);

4. 增删改

增删改用sqlx的exec

增 Insert

插入数据 要注意MySQL占位符用的? ,? ,? 而PG用的$1 ,$2 ,$3

func testInsert() {
    
    
	sqli := `INSERT INTO "public"."user_info" 
    ("uid", "name", "group", "balance", "proportion", "create_time", "comments") 
	VALUES ($1, $2, $3, $4, $5, $6, $7);`
	_, err := db.Exec(sqli, 100, "名字", "组", 2.33, 27.148, "2022-05-08 18:11:22", nil)
	if err != nil {
    
    
		fmt.Printf("insert failed, err:%v\n", err)
		return
	}
	fmt.Printf("insert success\n")
}

删 Delete

删除id为6的行

func testDelete() {
    
    
	sqld := `DELETE FROM "public"."user_info" WHERE "id" = $1`
	ret, err := db.Exec(sqld, 6)
	if err != nil {
    
    
		fmt.Printf("delete failed, err:%v\n", err)
		return
	}
	n, err := ret.RowsAffected() // 操作影响的行数
	if err != nil {
    
    
		fmt.Printf("get RowsAffected failed, err:%v\n", err)
		return
	}
	fmt.Printf("delete success, affected rows:%d\n", n)
}

改 Update

把uid为100的name改为张三

func testUpdate() {
    
    
	sqlu := `UPDATE "public"."user_info" SET "name" = $1 WHERE "uid" = $2`
	ret, err := db.Exec(sqlu, "张三", 100)
	if err != nil {
    
    
		fmt.Printf("update failed, err:%v\n", err)
		return
	}
	n, err := ret.RowsAffected() // 操作影响的行数
	if err != nil {
    
    
		fmt.Printf("get RowsAffected failed, err:%v\n", err)
		return
	}
	fmt.Printf("update success, affected rows:%d\n", n)
}

5. 查

查询前先写一个结构体，查到后直接绑定

type UserInfoType struct {
    
    
	Id         int            `db:"id"`
	Uid        int64          `db:"uid"`
	Name       string         `db:"name"`
	Group      string         `db:"group"`
	Balance    float64        `db:"balance"`
	Proportion float64        `db:"proportion"`
	CreateTime time.Time      `db:"create_time"`
	Comments   sql.NullString `db:"comments"`
}

5.1 查询单行数据

func testSelectOne() {
    
    
	sqls := `SELECT * FROM "public"."user_info"  WHERE "uid" = $1`
	var user UserInfoType
	err := db.Get(&user, sqls, 100)
	if err != nil {
    
    
		fmt.Printf("get failed, err:%v\n", err)
		return
	}
	fmt.Printf("one user: %#v\n", user)
}

5.2 查询多行数据

func testSelectAll() {
    
    
	sqls := `SELECT * FROM "public"."user_info" WHERE "uid" > $1`
	var users []UserInfoType
	err := db.Select(&users, sqls, 0)
	if err != nil {
    
    
		fmt.Printf("query failed, err:%v\n", err)
		return
	}
	fmt.Printf("all users: %#v\n", users)
}

5.3 In查询

查询uid为 集合(2,3)的行

func testSelectIn() {
    
    
	uids := []int{
    
    2, 3}
	sqlin := `SELECT * FROM "public"."user_info" WHERE "uid" in(?)`
	query, args, err := sqlx.In(sqlin, uids)
	if err != nil {
    
    
		fmt.Printf("sqlin failed, err:%v\n", err)
		return
	}
	query = db.Rebind(query)
	fmt.Println(query)
	var users []UserInfoType
	err = db.Select(&users, query, args...)
	if err != nil {
    
    
		fmt.Printf("query failed, err:%v\n", err)
		return
	}
	fmt.Printf("all user: %#v\n", users)
}