sqlite3/sqlite3vfs/example_test.go

package sqlite3vfs_test

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

	_ "embed"

	_ "github.com/ncruces/go-sqlite3/driver"
	_ "github.com/ncruces/go-sqlite3/embed"
	"github.com/ncruces/go-sqlite3/sqlite3vfs"
	"github.com/psanford/httpreadat"
)

//go:embed testdata/test.db
var testDB []byte

func ExampleMemoryVFS_embed() {
	sqlite3vfs.Register("memory", sqlite3vfs.MemoryVFS{
		"test.db": sqlite3vfs.NewMemoryDB(testDB),
	})

	db, err := sql.Open("sqlite3", "file:test.db?vfs=memory&_pragma=journal_mode(memory)")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	_, err = db.Exec(`INSERT INTO users (id, name) VALUES (3, 'rust')`)
	if err != nil {
		log.Fatal(err)
	}

	rows, err := db.Query(`SELECT id, name FROM users`)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	for rows.Next() {
		var id, name string
		err = rows.Scan(&id, &name)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("%s %s\n", id, name)
	}
	// Output:
	// 0 go
	// 1 zig
	// 2 whatever
	// 3 rust
}

func ExampleReaderVFS_http() {
	sqlite3vfs.Register("httpvfs", sqlite3vfs.ReaderVFS{
		"demo.db": httpreadat.New("https://www.sanford.io/demo.db"),
	})

	db, err := sql.Open("sqlite3", "file:demo.db?vfs=httpvfs&mode=ro")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	magname := map[int]string{
		3: "thousand",
		6: "million",
		9: "billion",
	}
	rows, err := db.Query(`
		SELECT period, data_value, magntude, units FROM csv
			WHERE period > '2010'
			LIMIT 10`)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	for rows.Next() {
		var period, units string
		var value int64
		var mag int
		err = rows.Scan(&period, &value, &mag, &units)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("%s: %d %s %s\n", period, value, magname[mag], units)
	}
	// Output:
	// 2010.03: 17463 million Dollars
	// 2010.06: 17260 million Dollars
	// 2010.09: 15419 million Dollars
	// 2010.12: 17088 million Dollars
	// 2011.03: 18516 million Dollars
	// 2011.06: 18835 million Dollars
	// 2011.09: 16390 million Dollars
	// 2011.12: 18748 million Dollars
	// 2012.03: 18477 million Dollars
	// 2012.06: 18270 million Dollars
}

func ExampleReaderVFS_embed() {
	sqlite3vfs.Register("reader", sqlite3vfs.ReaderVFS{
		"test.db": sqlite3vfs.NewSizeReaderAt(bytes.NewReader(testDB)),
	})

	db, err := sql.Open("sqlite3", "file:test.db?vfs=reader&mode=ro")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	rows, err := db.Query(`SELECT id, name FROM users`)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	for rows.Next() {
		var id, name string
		err = rows.Scan(&id, &name)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("%s %s\n", id, name)
	}
	// Output:
	// 0 go
	// 1 zig
	// 2 whatever
}