函數Go執行數據庫選擇查詢並返回json輸出

Question

我正在編寫一個函數來執行對數據庫的select查詢。

輸入：字符串例如「Select some id，name，age from sometable」 此查詢每次更改。

輸出：以json格式輸出選擇查詢。

示例預期輸出： {「Data」：[{「id」：1，「name」：「abc」，「age」：40}，{「id」：2，「name」 XYZ」， 「年齡」：45}]}

樣品的實際輸出： { 「數據」：[[1， 「ABC」，40]，[2， 「XYZ」，45]]}

而不是ie列名：值，我只得到值。 如何獲得預期的輸出？

func executeSQL(queryStr string) []byte { 
connString := createConnectString() 
conn, err := sql.Open("mssql", connString) 
if err != nil { 
    log.Fatal("Error while opening database connection:", err.Error()) 
} 
defer conn.Close() 

rows, err := conn.Query(queryStr) 
if err != nil { 
    log.Fatal("Query failed:", err.Error()) 
} 
defer rows.Close() 

columns, _ := rows.Columns() 
count := len(columns) 

var v struct { 
    Data []interface{} // `json:"data"` 
} 

for rows.Next() { 
    values := make([]interface{}, count) 
    valuePtrs := make([]interface{}, count) 
    for i, _ := range columns { 
     valuePtrs[i] = &values[i] 
    } 
    if err := rows.Scan(valuePtrs...); err != nil { 
     log.Fatal(err) 
    } 
    v.Data = append(v.Data, values) 
} 
jsonMsg, err := json.Marshal(v) 
return jsonMsg 
} 

Answer 1

得到了解決方案。這是我做的。

func executeSQL(queryStr string) []byte { 
connString := createConnectString() 
conn, err := sql.Open("mssql", connString) 
if err != nil { 
    log.Fatal("Error while opening database connection:", err.Error()) 
} 
defer conn.Close() 

rows, err := conn.Query(queryStr) 
if err != nil { 
    log.Fatal("Query failed:", err.Error()) 
} 
defer rows.Close() 

columns, _ := rows.Columns() 
count := len(columns) 

var v struct { 
    Data []interface{} // `json:"data"` 
} 

for rows.Next() { 
    values := make([]interface{}, count) 
    valuePtrs := make([]interface{}, count) 
    for i, _ := range columns { 
     valuePtrs[i] = &values[i] 
    } 
    if err := rows.Scan(valuePtrs...); err != nil { 
     log.Fatal(err) 
    } 

//Created a map to handle the issue 
    var m map[string]interface{} 
    m = make(map[string]interface{}) 
    for i := range columns { 
     m[columns[i]] = values[i] 
    } 
    v.Data = append(v.Data, m) 
} 
jsonMsg, err := json.Marshal(v) 
return jsonMsg 
} 

讓我知道是否存在更好的解決方案。

Answer 2

這段代碼是直接從我的「沙箱」爲MSSQL（使用denisenkom /復mssqldb和jmoiron/SQLX） - 我認爲它有助於展示不同的方法和可能QueryIntoMap就是你要找的人：

package main 

import (
    "log" 
    "fmt" 
    _ "github.com/denisenkom/go-mssqldb" 
    "time" 
    "github.com/jmoiron/sqlx" 
    "encoding/json" 
) 

type Customer struct { 
    CustomerId string `db:"customerID" json:"customer_id"` 
    Company interface{} `db:"companyName" json:"company_name"` 
    Contact interface{} `db:"contactName" json:"contact_name"` 
} 

func main() { 
    connection := "server=192.168.55.3\\SqlExpress2012;database=Northwind;user id=me;Password=secret" 

    //QueryIntoMap(connection) 
    ScanIntoSlice(connection) 
} 

func QueryIntoMap(connection string) { 

    fmt.Println("QueryIntoMap sample") 
    fmt.Println("--------------------") 

    sel := `select customerId, companyName, contactName 
    from customers 
    where customerId = :id` 

    values := make(map[string]interface{}) 


    db, err := sqlx.Open("mssql", connection) 
    //db.MapperFunc(strings.ToUpper) 
    e(err) 
    defer db.Close() 
    tx := db.MustBegin() 
    stmt, err := tx.PrepareNamed(sel) 
    e(err) 

    stmt.QueryRowx(map[string]interface{}{"id": "BONAP"}).MapScan(values) 
    tx.Commit() 

    for k, v := range values { 
     fmt.Printf("%s %v\n", k, v) 
    } 

    js, err := json.Marshal(values) 
    if err != nil { 
     fmt.Println(err) 
    } 
    fmt.Println(string(js)) 
    fmt.Println("--------------------") 
} 

func ScanIntoStruct(connection string) { 
    fmt.Println("Scan into struct sample") 
    fmt.Println("--------------------") 

    db, err := sqlx.Open("mssql", connection) 
    e(err) 
    defer db.Close() 

    customer := Customer{} 

    rows, err := db.Queryx(`select customerID, companyName, contactName 
    from Customers`) 

    for rows.Next() { 
     err = rows.StructScan(&customer) 
     if err != nil { 
      log.Fatalln(err) 
     } 
     //fmt.Printf("%#v\n", user) 
     fmt.Printf("%-10s %-50v %-50v\n", 
      customer.CustomerId, 
      customer.Company, 
      customer.Contact) 
     js, err := json.Marshal(customer) 
     e(err) 
     fmt.Println(string(js)) 
    } 
    fmt.Println("--------------------") 

} 

func ScanIntoSlice(connection string) { 
    fmt.Println("Scan into slice sample") 
    fmt.Println("--------------------") 
    start := time.Now() 
    db, err := sqlx.Open("mssql", connection) 
    e(err) 
    defer db.Close() 

    customers := []Customer{} 

    err = db.Select(&customers, `select customerID, companyName, contactName from customers`) 
    e(err) 

    for i, customer := range customers { 
     fmt.Printf("%3d. %-10s %-50v %-50v\n", 
      i, 
      customer.CustomerId, 
      customer.Company, 
      customer.Contact) 
    } 
    js, err := json.Marshal(customers) 
    e(err) 

    fmt.Println(string(js)) 

    fmt.Printf("%s", time.Since(start)) 
    fmt.Println("--------------------") 

} 

func e(err error) { 
    if err != nil { 
     log.Fatal(err) 
    } 
}