golang数据库之查询

## 查询单条记录

```
package db
 
import (
    "model"    //调用model中定义的数据类型
)
//需要传递的形参以及返回的值个数和数据类型
func Login(account string, password string) (*model.User, error) {
    db, err := connect()
    if err != nil {
        return nil, err
    }
    defer db.Close()
 
    user := model.User{}
        //这里用的是QueryRow
    row := db.QueryRow("select id, account, password, avatar, pay_pwd, users_wallet, all_assets, available_assets,freeze_assets from users where account = ? and password = md5(?)", account, password)
 
    err = row.Scan(&user.ID, &user.Account, &user.Password, &user.Avatar, &user.Pay_pwd, &user.Users_wallet, &user.All_assets, &user.Available_assets, &user.Freeze_assets)
    if err != nil {
        return nil, err
    }
        //这里采用的是返回地址
    return &user, nil
}
```
## 数据库查询多条记录
```
package db
 
import (
    //"log"
    "model"
)
//返回的是一个数组
func CreateOrders(account string) ([]model.Order, error) {
    db, err := connect()
    if err != nil {
        return nil, err
    }
    defer db.Close()
 
    rows, err := db.Query("select * from orders where user_id = (select id from users where account = ?)", account)
    if err != nil {
        return nil, err
    }
    defer rows.Close()
    //定义一个数组
    var orders []model.Order
    order := model.Order{}
 
    for rows.Next() {
        err := rows.Scan(&order.ID, &order.User_ID, &order.Status, &order.Buy_sell, &order.Receipt_wat, &order.Payee, &order.Buy_sell_num, &order.Buy_sell_min, &order.Price, &order.Area, &order.Placard)
        if err != nil {
            return nil, err
        }
        //将每次循环出来的一条数据放入到数组中
        orders = append(orders, order)
    }
 
    err = rows.Err()
    if err != nil {
        return nil, err
    }
        //直接返回数组本身
    return orders, nil
}
```