dump #sql tables in #golang

tables.go

package main

import (
	"database/sql"
	"flag"
	"fmt"
	"log"

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

var (
	dbUser = flag.String("user", "user", "username")
	dbPass = flag.String("pass", "pass", "password")
	dbHost = flag.String("host", "tcp(127.0.0.1:3306)", "hostname")
	dbName = flag.String("name", "base", "database")
)

func showTables(db *sql.DB) ([]string, error) {
	rows0, err := db.Query("show tables")
	if err != nil {
		return nil, err
	}
	defer rows0.Close()

	n := 0
	tables := make([]string, 0)
	for rows0.Next() {
		var s string

		n++
		err = rows0.Scan(&s)
		if err != nil {
			return nil, fmt.Errorf("rows.Scan %d failed: %v", n, err)
		}

		tables = append(tables, s)
	}

	return tables, nil
}

type Desc struct {
	Name    string
	Type    string
	Null    string
	Key     *string
	Default *string
	Extra   *string
}

func describe(db *sql.DB, table string) (map[string]*Desc, error) {
	rows0, err := db.Query("describe " + table)
	if err != nil {
		return nil, err
	}
	defer rows0.Close()

	n := 0
	descs := make(map[string]*Desc)
	for rows0.Next() {
		var d Desc

		n++
		err = rows0.Scan(&d.Name, &d.Type, &d.Null, &d.Key, &d.Default, &d.Extra)
		if err != nil {
			return nil, fmt.Errorf("rows.Scan %d failed: %v", n, err)
		}

		descs[d.Name] = &d
	}

	return descs, nil
}

func main() {
	flag.Parse()

	dbSrc := fmt.Sprintf("%s:%s@%s/%s?parseTime=true", *dbUser, *dbPass, *dbHost, *dbName)

	db, err := sql.Open("mysql", dbSrc)
	if err != nil {
		log.Fatalf("sql.Open failed: %v", err)
	}
	defer db.Close()

	// sql.Open() does not establish any connections to the database ...

	err = db.Ping()
	if err != nil {
		log.Fatalf("db.Ping failed: %v", err)
	}

	tables, err := showTables(db)
	if err != nil {
		log.Fatalf("showTables failed: %v\n", err)
	}

	for _, table := range tables {
		ds, err := describe(db, table)
		if err != nil {
			log.Fatalf("describe failed: %v\n", err)
		}

		fmt.Printf("%s:\n", table)
		for _, d := range ds {
			fmt.Printf("\t%-20s %s\n", d.Name, d.Type)
		}
	}
}