GO DB.Query用法及代碼示例

GO語言"database/sql"包中"DB.Query"類型的用法及代碼示例。

用法:

func(db *DB) Query(query string, args ...any)(*Rows, error)

Query 執行返回行的查詢，通常是 SELECT。 args 用於查詢中的任何占位符參數。

查詢在內部使用 context.Background；要指定上下文，請使用QueryContext

示例(多個結果集)：

package main

import (
	"context"
	"database/sql"
	"log"
)

var (
	ctx context.Context
	db  *sql.DB
)

func main() {
	age := 27
	q := `
create temp table uid (id bigint); -- Create temp table for queries.
insert into uid
select id from users where age < ?; -- Populate temp table.

-- First result set.
select
	users.id, name
from
	users
	join uid on users.id = uid.id
;

-- Second result set.
select 
	ur.user, ur.role
from
	user_roles as ur
	join uid on uid.id = ur.user
;
	`
	rows, err := db.Query(q, age)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	for rows.Next() {
		var (
			id   int64
			name string
		)
		if err := rows.Scan(&id, &name); err != nil {
			log.Fatal(err)
		}
		log.Printf("id %d name is %s\n", id, name)
	}
	if !rows.NextResultSet() {
		log.Fatalf("expected more result sets: %v", rows.Err())
	}
	var roleMap = map[int64]string{
		1: "user",
		2: "admin",
		3: "gopher",
	}
	for rows.Next() {
		var (
			id   int64
			role int64
		)
		if err := rows.Scan(&id, &role); err != nil {
			log.Fatal(err)
		}
		log.Printf("id %d has role %s\n", id, roleMap[role])
	}
	if err := rows.Err(); err != nil {
		log.Fatal(err)
	}
}

相關用法

注：本文由純淨天空篩選整理自golang.google.cn大神的英文原創作品 DB.Query。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。