go-sql-driver将driver.Value类型[] uint8转换为float64：无效的语法

Question

我使用gorm查询mysql sum sql，但是，发生错误：

sql: Scan error on column index 0, name "transaction_amount": converting driver.Value type []uint8 ("-1,225.67") to a float64: invalid syntax

这是我定义的结构：

type AdsPayment struct {
    Model
    SellerID          string    `gorm:"size:32"`
    TransactionType   string    `json:"transactionType"`
    Currency          string    `gorm:"size:8" json:"currency"`
    BaseAmount        float64   `gorm:"type:decimal(10,2)" json:"baseAmount"`
    TransactionAmount float64   `gorm:"type:decimal(10,2)" json:"transactionAmount"`
    TaxAmount         float64   `gorm:"type:decimal(10,2)" json:"taxAmount"`
    InvoiceID         string    `gorm:"size:64" json:"invoiceId"`
    PostedDate        time.Time `json:"postedDate"`}

这是查询代码：

var ads AdsPayment
DB.Select(floatFmt+"(SUM(transaction_amount), 2) As transaction_amount").Group(dateFmt).First(&ads, "seller_id=? And currency=? And "+dateFmt+"=?", "A3VFS4SD0I640V", "USD", "2019-01")