英文:
How to set Limit or query Go Language Mysql?
问题
如何在Go语言中设置mysql的限制？我在php中尝试过，它可以工作，但在Go语言中，它显示<nil>值，不知道如何修复。
php代码示例：
$sql = "SELECT My_Data FROM page_data";// 或者$sql = "SELECT My_Data FROM page_data limit 0,10";
Go代码示例：
myquery, err := db.Prepare("SELECT pages_old FROM app_library")fmt.Println("Data---", myquery)
当我运行以下命令时：
q := "SELECT `data` FROM `page_data`"rows, err := db.Query(q)if err != nil {fmt.Println(err)}defer rows.Close()for rows.Next() {var data string // 与数据库中的类型相同if err := rows.Scan(&data); err != nil {log.Fatal(err)}fmt.Println(data)}
然后出现以下错误：
Error: error:-- commands out of sync. Did you run multiple statements at once?panic: runtime error: invalid memory address or nil pointer dereferencepanic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x10bee7a]
英文:
How to Set mysql limit in Go Language? I try it to php it is working but in the Go language, it show <nil> value didn't know how to fixed
php:--- $sql = "SELECT My_Data FROM page_data"; or $sql = "SELECT My_Data FROM page_data limit 0,10";Go :- SHOW <nil> >>>myquery, err := db.Prepare("SELECT pages_old FROM app_library")fmt.Println("Data---", myquery)
When I hit the below command :-
q := "SELECT data FROM page_data"
rows, err := db.Query(q)if err != nil {fmt.Println(err)}defer rows.Close()for rows.Next() {var data string // same database typeif err := rows.Scan(&data); err != nil {log.Fatal(err)}fmt.Println(data)}
Then Got the below error:
> Error: error :-- commands out of sync. Did you run multiple statements
> at once? panic: runtime error: invalid memory address or nil pointer
> dereference panic: runtime error: invalid memory address or nil
> pointer dereference [signal SIGSEGV: segmentation violation code=0x1
> addr=0x0 pc=0x10bee7a]
答案1
得分: 1
[Prepare][1] 用于创建一个预处理语句，以供以后查询或执行使用。
如果你想执行一个返回行的查询，请使用 [Query][2]。
完整示例：
package mainimport ("database/sql""fmt""log"_ "github.com/go-sql-driver/mysql")const (dbUser = ""dbPassword = ""dbName = "")func main() {db, err := sql.Open("mysql", dbUser+":"+dbPassword+"@/"+dbName+"?charset=utf8")if err != nil {log.Fatal(err)}q := "SELECT `data` FROM `page_data`"rows, err := db.Query(q)if err != nil {fmt.Println(err)}defer rows.Close()for rows.Next() {var data string // 相同的数据库类型if err := rows.Scan(&data); err != nil {log.Fatal(err)}fmt.Println(data)}}
示例已经被编辑过了。
[1]: https://golang.org/pkg/database/sql/#DB.Prepare
[2]: https://golang.org/pkg/database/sql/#DB.Query
英文:
[Prepare][1] used to creates a prepared statement for later queries or executions.
if you want to executes a query that returns rows use [Query][2]
Full Example:
package mainimport ("database/sql""fmt""log"_ "github.com/go-sql-driver/mysql")const (dbUser = ""dbPassword = ""dbName = "")func main() {db, err := sql.Open("mysql", dbUser+":"+dbPassword+"@/"+dbName+"?charset=utf8")if err != nil {log.Fatal(err)}q := "SELECT `data` FROM `page_data`"rows, err := db.Query(q)if err != nil {fmt.Println(err)}defer rows.Close()for rows.Next() {var data string // same database typeif err := rows.Scan(&data); err != nil {log.Fatal(err)}fmt.Println(data)}}
example it has been edited
[1]: https://golang.org/pkg/database/sql/#DB.Prepare
[2]: https://golang.org/pkg/database/sql/#DB.Query
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