Golang如何使用sql查詢行檢查錯誤

Question

我正在使用postgres數據庫，並以用於API的字符串形式從數據庫返回Json響應。我的問題是，我不知道如何使用QueryRow方法檢查錯誤。這就是我的代碼，它正常工作。這只是表明Json的迴應。但是我有一個自定義函數，如果代碼出現錯誤，QueryRow不會讓我檢查錯誤是否有任何建議？

var result string 
db.QueryRowContext(ctx,"select json_build_object('Profile', array_to_json(array_agg(t))) from" + 
        " (select p.id,p.fullname,z.thirtylatmin as latmin,z.thirtylatmax as latmax,z.thirtylonmin as lonmin," + 
          "z.thirtylonmax as lonmax,p.latitudes,p.longitudes,p.location as location" + 
        ",p.picture,p.is_gold from profiles p join zips z on (z.city='Boston' " + 
       "and z.state='MA') where email=$1) t;",email).Scan(&result) 

io.writestring(w, result) 

如果我上面的代碼更改爲此然後它用錯誤的郵件，但是我怎麼能返回一個字符串

SqlStatement,err := db.QueryContext(ctx,"select json_build_object('Profile', array_to_json(array_agg(t))) from" + 
       " (select p.id,p.fullname,z.thirtylatmin as latmin,z.thirtylatmax as latmax,z.thirtylonmin as lonmin," + 
         "z.thirtylonmax as lonmax,p.latitudes,p.longitudes,p.location as location" + 
       ",p.picture,p.is_gold from profiles p join zips z on (z.city='Boston' " + 
      "and z.state='MA') where email=$1) t;",email) 

      if err != nil { 
       log_errors("sql statement error",err.Error(),w) 
      } 
      io.WriteString(w, "How can I get SqlStatement as 1 whole String ??") 

上面的語句，讓我記錄任何錯誤，並將其插入到數據庫，現在我怎麼能得到SqlStatement返回爲1整個字符串？ SQL語句返回完美，現在我只需要讓它進入io.WriteString以字符串格式

Answer 1

你應該只檢查Row.Scan方法的返回值，就像這樣：

row := db.QueryRow(
    `SELECT 
     json_build_object('Profile', array_to_json(array_agg(t))) 
    FROM 
     (
      SELECT 
       p.id, 
       p.fullname, 
       z.thirtylatmin as latmin, 
       z.thirtylatmax as latmax, 
       z.thirtylonmin as lonmin, 
       z.thirtylonmax as lonmax, 
       p.latitudes, 
       p.longitudes, 
       p.location as location, 
       p.picture, 
       p.is_gold 
      FROM 
       profiles p 
      JOIN zips z on (z.city='Boston'AND z.state='MA') 
      WHERE 
       email=$1 
     ) t`, 
    email, 
) 

var result string 
if err := Scan(&result); err != nil { 
    log.Fatal(err) 
} 

fmt.Fprint(w, result)