Add a code example for inserting many records in a single query

examples/insert_many/main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/vingarcia/ksql"
+	"github.com/vingarcia/ksql/adapters/ksqlite3"
+)
+
+var UsersTable = ksql.NewTable("users")
+
+type User struct {
+	ID   int    `ksql:"id"`
+	Name string `ksql:"name"`
+	Age  int    `ksql:"age"`
+
+	UpdatedAt time.Time `ksql:"updated_at,timeNowUTC"`
+	CreatedAt time.Time `ksql:"created_at,timeNowUTC/skipUpdates"`
+}
+
+func main() {
+	ctx := context.Background()
+
+	db, err := ksqlite3.New(ctx, "/tmp/hello.sqlite", ksql.Config{
+		MaxOpenConns: 1,
+	})
+	if err != nil {
+		panic(err.Error())
+	}
+	defer db.Close()
+
+	// In the definition below, please note that BLOB is
+	// the only type we can use in sqlite for storing JSON.
+	_, err = db.Exec(ctx, `CREATE TABLE IF NOT EXISTS users (
+	  id INTEGER PRIMARY KEY,
+		age INTEGER,
+		name TEXT,
+		address BLOB,
+		created_at DATETIME,
+		updated_at DATETIME
+	)`)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	db.Exec(ctx, `DELETE FROM users`)
+
+	err = insertManyUsers(ctx, db, []User{
+		{Name: "User1", Age: 22},
+		{Name: "User2", Age: 32},
+		{Name: "User3", Age: 42},
+	})
+	if err != nil {
+		panic(err.Error())
+	}
+
+	var users []User
+	err = db.Query(ctx, &users, `FROM users WHERE name like 'User%'`)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	b, err := json.MarshalIndent(users, "", "  ")
+	if err != nil {
+		panic(err.Error())
+	}
+
+	fmt.Println("users:", string(b))
+}
+
+func insertManyUsers(ctx context.Context, db ksql.Provider, users []User) error {
+	if len(users) == 0 {
+		return nil
+	}
+
+	query := []string{}
+	values := []interface{}{}
+
+	for i, user := range users {
+		query = append(query, fmt.Sprintf(`($%d, $%d, $%d, $%d)`, i*5+1, i*5+2, i*5+3, i*5+4))
+		values = append(values, user.Age, user.Name, time.Now().UTC(), time.Now().UTC())
+	}
+
+	_, err := db.Exec(ctx, `INSERT INTO users (age, name, created_at, updated_at) VALUES `+strings.Join(query, ", "), values...)
+	return err
+}