Hit the dangerous wobbly ground running: Quick&dirty up to speed with go database/sql

dirtysql.go

type must struct {
	db      *sql.DB
	stmt    *sql.Stmt
	rows    *sql.Rows
	err     error
	closers []io.Closer
}

func Open(dbdriver, dsn string) *must {
	m := &must{}
	m.db, m.err = sql.Open(dbdriver, dsn)
	m.mayPanic(m.db)
	return m
}

func (m *must) mayPanic(closer interface{}) {
	if m.err != nil {
		panic(m.err)
	}
	if c, ok := closer.(io.Closer); ok {
		m.closers = append(m.closers, c)
	}
}

func (m *must) Close() {
	for i := len(m.closers) - 1; i >= 0; i-- {
		_ = m.closers[i].Close()
	}
}

func (m *must) Exec(query string, args ...interface{}) sql.Result {
	if m.rows != nil {
		m.rows, _ = nil, m.rows.Close()
	}
	var result sql.Result
	result, m.err = m.db.Exec(query, args...)
	m.mayPanic(nil)
	return result
}

func (m *must) QueryColumns(query string, args ...interface{}) (cols []string) {
	if m.rows != nil {
		m.rows, _ = nil, m.rows.Close()
	}
	m.rows, m.err = m.db.Query(query, args...)
	m.mayPanic(m.rows)
	if !m.rows.Next() {
		return nil
	}
	cols, m.err = m.rows.Columns()
	m.mayPanic(m.rows)
	return cols
}

func (m *must) ScanNext(args ...interface{}) (hasNext bool) {
	m.err = m.rows.Scan(args...)
	m.mayPanic(nil)
	return m.rows.Next()
}

Used like this:

import (
    "database/sql"
    "fmt"
    _ "github.com/go-sql-driver/mysql"
    "io"
    "os"
    "strings"
)

func main() {
    dsn := os.Getenv("MYSQL_DSN")
    if dsn == "" {
        dsn = "root@tcp(localhost:3306)/"
    }
    mysql := Open("mysql", dsn)
    defer mysql.Close()
    cols := mysql.QueryColumns("SHOW SCHEMAS")
    if len(cols) == 0 {
        panic("Can't show schemas")
    }
    receivers := make([]interface{}, len(cols))
    data := make([]string, len(receivers))
    for i := 0; i < len(receivers); i++ {
        receivers[i] = &data[i]
    }
    fmt.Println(strings.Join(cols, "\t|\t"))
    fmt.Println("=====================================")
    for mysql.ScanNext(receivers...) {
        fmt.Println(strings.Join(data, "\t|\t"))
    }
}