How to export database records from Golang?

Use the database/sql package in Go to export database records. The method is as follows: install the database/sql package; connect to the database; write SQL query statements; execute the query and store the results; iterate the result set and obtain the record values. The exported records can be further converted to CSV format and output.

Export records from the database using Golang

In Golang, we can use the database/sql package to export records from the database. The following are the steps:

1. Install dependencies

Use the following command to install the database/sql package:

go get -u github.com/go-sql-driver/mysql

2. Connect to the database

Establish a connection to the database:

import (
    "database/sql"
    "fmt"

    _ "github.com/go-sql-driver/mysql" // 注册 MySQL 驱动
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(localhost:3306)/database")
    if err != nil {
        // 处理错误
    }
    defer db.Close()
}

3. Write an export query

Write a SQL query to export records:

SELECT * FROM table_name;

4. Execute the query

Use the Query function to execute the query and store the results in *sql.Rows:

rows, err := db.Query("SELECT * FROM table_name")
if err != nil {
    // 处理错误
}

5. Iterate the result set

UseNext The function iterates through the result set and gets each record.

for rows.Next() {
    // 获取每一行的列值
    var id int
    var name string
    var age int

    err := rows.Scan(&id, &name, &age)
    if err != nil {
        // 处理错误
    }

    // 使用这些值进行进一步的操作（例如导出到 CSV 文件）
}

Practical case: Export to CSV file

The following is the code to export the results to a CSV file:

import (
    "csv"
    "os"
)

// 将记录导出到 CSV 文件
func exportToCSV(records [][]string) error {
    f, err := os.Create("export.csv")
    if err != nil {
        return err
    }
    defer f.Close()

    w := csv.NewWriter(f)
    if err := w.WriteAll(records); err != nil {
        return err
    }

    return nil
}

// 将结果集转换成 CSV 记录
func toCSVRecords(rows *sql.Rows) ([][]string, error) {
    var records [][]string
    for rows.Next() {
        var id int
        var name string
        var age int

        if err := rows.Scan(&id, &name, &age); err != nil {
            return nil, err
        }

        records = append(records, []string{strconv.Itoa(id), name, strconv.Itoa(age)})
    }

    return records, nil
}

Usage example:

// 从数据库导出记录并导出到 CSV 文件
func main() {
    db, err := sql.Open("mysql", "user:password@tcp(localhost:3306)/database")
    if err != nil {
        // 处理错误
    }
    defer db.Close()

    rows, err := db.Query("SELECT * FROM table_name")
    if err != nil {
        // 处理错误
    }

    records, err := toCSVRecords(rows)
    if err != nil {
        // 处理错误
    }

    if err := exportToCSV(records); err != nil {
        // 处理错误
    }
}

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