SNOW-829187 Add multistatement query example (#810)

cmd/multistatement/.gitignore

@@ -0,0 +1 @@
+multistatement

cmd/multistatement/Makefile

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+include ../../gosnowflake.mak
+CMD_TARGET=multistatement
+
+## Install
+install: cinstall
+
+## Run
+run: crun
+
+## Lint
+lint: clint
+
+## Format source codes
+fmt: cfmt
+
+.PHONY: install run lint fmt

cmd/multistatement/multistatement.go

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+package main
+
+import (
+	"context"
+	"database/sql"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+
+	sf "github.com/snowflakedb/gosnowflake"
+)
+
+func getDSN() (string, *sf.Config, error) {
+	env := func(key string, failOnMissing bool) string {
+		if value := os.Getenv(key); value != "" {
+			return value
+		}
+		if failOnMissing {
+			log.Fatalf("#{key} environment not set")
+		}
+		return ""
+	}
+
+	account := env("SNOWFLAKE_TEST_ACCOUNT", true)
+	user := env("SNOWFLAKE_TEST_USER", true)
+	password := env("SNOWFLAKE_TEST_PASSWORD", true)
+	host := env("SNOWFLAKE_TEST_HOST", false)
+	portStr := env("SNOWFLAKE_TEST_PORT", false)
+	protocol := env("SNOWFLAKE_TEST_PROTOCOL", false)
+
+	port := 443
+	var err error
+	if len(portStr) > 0 {
+		port, err = strconv.Atoi(portStr)
+		if err != nil {
+			return "", nil, err
+		}
+	}
+
+	cfg := &sf.Config{
+		Account:  account,
+		User:     user,
+		Password: password,
+		Host:     host,
+		Port:     port,
+		Protocol: protocol,
+	}
+
+	dsn, err := sf.DSN(cfg)
+	return dsn, cfg, err
+}
+
+func main() {
+	if !flag.Parsed() {
+		flag.Parse()
+	}
+
+	dsn, config, err := getDSN()
+	if err != nil {
+		log.Fatalf("Failed to create DSN from config: %v, error: %v", config, err)
+	}
+
+	db, err := sql.Open("snowflake", dsn)
+	if err != nil {
+		log.Fatalf("Failed to connect, dsn: %v, error: %v", dsn, err)
+	}
+
+	defer db.Close()
+
+	numberOfQueries := 2
+	query := `
+		WITH table1 AS (SELECT 'table 1, row 1', 11 UNION SELECT 'table 1, row 2', 12)
+		SELECT * FROM table1;
+
+		WITH table2 AS (SELECT 'table 2, row 1', 21 UNION SELECT 'table 2, row 2', 22)
+		SELECT * FROM table2;
+	`
+
+	context, err := sf.WithMultiStatement(context.Background(), numberOfQueries)
+	if err != nil {
+		log.Fatalf("Error while creating multi statement context: %v", err)
+	}
+
+	result, err := db.QueryContext(context, query)
+	if err != nil {
+		log.Fatalf("Error while querying snowflake: %v", err)
+	}
+
+	defer result.Close()
+
+	for result.NextResultSet() {
+		for result.Next() {
+			var str string
+			var int int
+			err := result.Scan(&str, &int)
+			if err != nil {
+				log.Fatalf("Error while scanning row: %v", err)
+			}
+			fmt.Println(str, " | ", int)
+		}
+	}
+	if result.Err() != nil {
+		log.Fatalf("Error while reading results: %v", err)
+	}
+}