Go language sqlx library operation SQLite3 database addition, deletion, modification and query

0. quote

sqlx Than database/sql It's better to use a little , In fact, almost …
sqlx Address :https://github.com/jmoiron/sqlx

import (
	"database/sql"
	"fmt"
	"github.com/jmoiron/sqlx"
	_ "github.com/mattn/go-sqlite3"
)

1. Connect to database

• sql.Open
• sql.Close

var db *sql.DB

func InitDB() (err error) {
    
	dsn := "./data.db"
	db, err = sql.Open("sqlite3",dsn)
	if err != nil {
    
		fmt.Printf("connect DB failed, err:%v\n", err)
		return
	}
	return
}

func Close()  {
    
	db.Close()
}

Generally, there is no error when connecting to the database , If the file does not exist, it will be created

2. Create data table

SQLite A file is a database , Just create a new data table under the database

func testCreateTable() error {
    
	sqlc := ` CREATE TABLE "user_info" ( "id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "uid" INTEGER(8) NOT NULL, "name" text(255) NOT NULL, "group" TEXT(255) NOT NULL, "balance" integer(8) NOT NULL, "proportion" real(8) NOT NULL, "create_time" integer(4) NOT NULL, "comments" TEXT(255) ); CREATE INDEX "indexs" ON "user_info" ( "name", "group" ); CREATE UNIQUE INDEX "uniques" ON "user_info" ( "uid" ); `
	_, err := db.Exec(sqlc)
	if err != nil {
    
		return err
	}
	return nil
}

3. Additions and deletions

Addition, deletion, modification and MySQL PostgreSQL It's almost the same
Refer to the previous article ：https://blog.csdn.net/xuehu96/article/details/124648300
The code hardly needs to be changed

After testing , Place holder with $1, $2, $3 and ?,?,? It's all right

3.1 insert

func testInsert() error {
    
	sqli := `INSERT INTO "main"."user_info" ("uid", "name", "group", "balance", "proportion", "create_time", "comments") VALUES ($1, $2, $3, $4, $5, $6, $7);`
	_, err := db.Exec(sqli, 100, "xuehu96", " Group ", 2.33, 27.148, "2022-06-27 18:11:22", nil)
	if err != nil {
    
		return err
	}
	fmt.Printf("insert success\n")
	return nil
}

3.2 delete

Delete id by 2 The line of

func testDelete() error {
    
	sqld := `DELETE FROM "main"."user_info" WHERE "id" = $1`
	ret, err := db.Exec(sqld, 2)
	if err != nil {
    
		fmt.Printf("delete failed, err:%v\n", err)
		return err
	}
	n, err := ret.RowsAffected() //  Number of rows affected by operation 
	if err != nil {
    
		fmt.Printf("get RowsAffected failed, err:%v\n", err)
		return err
	}
	fmt.Printf("delete success, affected rows:%d\n", n)
	return nil
}

3.3 update

hold uid by 3 Of name Change to Zhang San

func testUpdate() error {
    
	sqlu := `UPDATE "main"."user_info" SET "name" = $1 WHERE "uid" = $2`
	//sqlu := `UPDATE "main"."user_info" SET "name" = ? WHERE "uid" = ?` //  use ? Space occupying is also OK 
	ret, err := db.Exec(sqlu, " Zhang San ", 3)
	if err != nil {
    
		fmt.Printf("update failed, err:%v\n", err)
		return err
	}
	n, err := ret.RowsAffected() //  Number of rows affected by operation 
	if err != nil {
    
		fmt.Printf("get RowsAffected failed, err:%v\n", err)
		return err
	}
	fmt.Printf("update success, affected rows:%d\n", n)
	return nil
}

4. check

Write a query structure first , Bind directly after finding

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 string         `db:"create_time"` // SQLite Doesn't seem to support time.Time
	Comments   sql.NullString `db:"comments"`
}

4.1 Query single line data

func testSelectOne() error {
    
	sqls := `SELECT * FROM "main"."user_info" WHERE "uid" = $1`
	var user UserInfoType
	err := db.Get(&user, sqls, 3)
	if err != nil {
    
		fmt.Printf("get failed, err:%v\n", err)
		return err
	}
	fmt.Printf("one user: %#v\n", user)
	return nil
}

4.2 Query multiple rows of data

func testSelectAll() error {
    
	sqls := `SELECT * FROM "main"."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 err
	}
	fmt.Printf("all users: %#v\n", users)
	return nil
}

5. main function

func main() {
    
	err := InitDB()
	if err != nil {
    
		panic(err)
	}
	defer CloseDB()

	err = testSelectAll()
	if err != nil {
    
		panic(err)
	}
}