How to write table data into a nested struct in Go

Summary

I am trying to write data from several postgres tables into a nested Go struct for the purpose of returning a single json response to a GET request within my web app.

Questions

1. Is the way I'm declaring a nested struct reasonable from a Go best practices perspective, or is there a reason I should avoid this method and do it another way?
2. What am I doing wrong in Step 3 to prevent my code from working? (I fear the answer is 'everything')

What I've got so far

1. I've declared my struct of structs

type MainObject struct {

	SubObjects []struct {
		SpecificDetail string `json:"specific-detail"`
	                       }  `json:"sub-object"`

    ...(other []structs)...
}

2. I've retrieved rows from the tables

func getMainObjectHandler(w http.ResponseWriter, r *http.Request) {
	
    ...(database connnection)...
	
    MainObjectID := r.URL.Query().Get("moid")
	if MainObjectID != "null" {
		NewMainObject := MainObject{}
		SubObjectDetail_rows, err := db.Query("SELECT specific_detail from the_table WHERE moid= '" + MainObjectID + "'")
		if err != nil {
			log.Fatalf("could not execute query: %v", err)
		}
        
        ...(other db.Query rows)...

3. I've tried (and failed) to build the row data into the struct.

	    for SubObjectDetail_rows.Next() {
		    SpecificDetail := NewMainObject.SubObject.SpecificDetail{}
	        SubObjectDetail_rows.Scan(&SpecificDetail)
		    SubObject = append(SubObject, SpecificDetail)
        }
        NewMainObject = append(MainObject, SubObject)
		defer persona_rows.Close()

4. Finally, I've set up Marshal and write.

		NMOListBytes, err := json.Marshal(NewMainObject)
		if err != nil {
			fmt.Println(fmt.Errorf("Error: %v", err))
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		w.Write(NMOListBytes)

Firstly, please use placeholders when creating your SQL query to avoid injections:

// db.Query("SELECT specific_detail from the_table WHERE moid= '" + MainObjectID + "'")  // not this
db.Query("SELECT specific_detail from the_table WHERE moid=?", MainObjectID)

Unless you're using a framework like GORM you can't Scan() into a single struct value.
From the docs:

> Scan copies the columns in the current row into the values pointed at
> by dest. The number of values in dest must be the same as the number
> of columns in Rows.

It looks like you're pulling JSON from a DB query, as you're only querying one column, so you probably want:

var bs []byte // get raw JSON bytes

err = SubObjectDetail_rows.Scan(&bs) 
if err != nil { /* always check errors */ }

and then unmarshal them to your struct:

err = json.Unmarshal(bs, &SpecificDetail)
if err != nil { /* ... */ }