英文:
MySQL Insert Float32 and Float64 Go
问题
我正在尝试向MySQL表中插入一行数据:
package main
import (
"strconv"
"io/ioutil"
"strings"
"os/exec"
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
func main() {
temp_cpu := getCPUTemp() // 返回 float32
temp_gpu := getGPUTemp() // 返回 float64
db, err := sql.Open("mysql", "user:pass@/sysStats")
handleError(err)
_, err = db.Query("INSERT INTO temperatures (id, cpu, gpu, timestamp) VALUES (?, ?, ?, ?)", 1, temp_gpu, temp_cpu, time.Now())
handleError(err)
db.Close()
return
}
它成功构建,但当我运行生成的二进制文件时,它在很长时间后超时,并显示一个通用的超时错误。
该表具有以下模式:
+----------------+-----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------+-----------+------+-----+---------+-------+
| idtemperatures | int(11) | NO | PRI | NULL | |
| cpu | float | YES | | NULL | |
| gpu | float | YES | | NULL | |
| timestamp | timestamp | YES | | NULL | |
+----------------+-----------+------+-----+---------+-------+
我在与MySQL实例托管的同一台服务器上运行此代码,并且可以在终端中使用用户/密码访问数据库。
有什么帮助吗?
谢谢!
英文:
I'm trying to insert a row into a MySQL table:
package main
import (
"strconv"
"io/ioutil"
"strings"
"os/exec"
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
func main() {
temp_cpu := getCPUTemp() // returns float32
temp_gpu := getGPUTemp() // returns float64
db, err := sql.Open("mysql", "user:pass@/sysStats")
handleError(err)
_, err = db.Query("INSERT INTO temperatures (id, cpu, gpu, timestamp) VALUES (?, ?, ?, ?)", 1, temp_gpu, temp_cpu, time.Now())
handleError(err)
db.Close()
return
}
It builds successfully but when I run the resulting binary it just times out after a long time with a generic timeout error.
The table has the following schema:
+----------------+-----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------+-----------+------+-----+---------+-------+
| idtemperatures | int(11) | NO | PRI | NULL | |
| cpu | float | YES | | NULL | |
| gpu | float | YES | | NULL | |
| timestamp | timestamp | YES | | NULL | |
+----------------+-----------+------+-----+---------+-------+
I am running this on the same server the MySQL instance is hosted and I can access the database with the user/password from the terminal.
Any help?
Thanks!
答案1
得分: 0
你的数据库中的id/主键字段被称为"idtemperatures",而你在SQL语句中使用了"id"。
另外,由于你执行的是一个"INSERT"语句而不是查询,你应该使用"DB.Exec()"方法来执行它。你永远不应该使用"DB.Query()"来执行DML(数据操作语言)语句。
如果无法连接到数据库,你可能会遇到超时错误。确保它使用默认的协议(TCP)和主机(localhost:3306)。另一个原因可能是因为你使用"DB.Query()"来执行SQL的"INSERT"语句,而"DB.Query()"返回一个"*sql.Rows"值,它会一直持有数据库连接,直到你使用"Rows.Close()"方法关闭它——而你从未这样做过;你甚至没有存储返回的"db.Rows"值。
此外,你应该在打开数据库后的错误检查之后,作为延迟语句调用"db.Close()"。
修正后的示例代码:
db, err := sql.Open("mysql", "user:pass@/sysStats")
if err != nil {
fmt.Println("打开数据库失败:", err)
return
}
defer db.Close()
s := "INSERT INTO temperatures (idtemperatures, cpu, gpu, timestamp) VALUES (?, ?, ?, ?)"
res, err = db.Exec(s, 1, temp_gpu, temp_cpu, time.Now())
if err != nil {
fmt.Println("执行INSERT失败:", err)
} else {
n, err := res.RowsAffected()
fmt.Println("INSERT执行成功,受影响的行数:", n, err)
}
英文:
The id / primary key field in your db is called "idtemperatures"
and you used "id"
in your SQL statement.
Also since you're not executing a query (but an INSERT
), you should use the DB.Exec()
method to execute it. You should never use DB.Query()
to execute DML (Data Manipulation Language) statements.
You may get a timeout error if you can't connect to your database. Make sure it uses default protocol (TCP) and host (localhost:3306). Another reason may be because you used DB.Query()
to execute your SQL INSERT
statement, and DB.Query()
returns an *sql.Rows
value which holds a database connection until you close it with the Rows.Close()
method - which you never do; you didn't even store the returned db.Rows
value.
Also you should call db.Close()
as a deferred statement, right after the error check after opening it.
Corrected example:
db, err := sql.Open("mysql", "user:pass@/sysStats")
if err != nil {
fmt.Println("Failed to open DB:", err)
return
}
defer db.Close()
s := "INSERT INTO temperatures (idtemperatures, cpu, gpu, timestamp) VALUES (?, ?, ?, ?)"
res, err = db.Exec(s, 1, temp_gpu, temp_cpu, time.Now())
if err != nil {
fmt.Println("Failed to execute INSERT:", err)
} else {
n, err := res.RowsAffected()
fmt.Println("INSERT executed, rows affected: ", n, err)
}
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