first prototype of an actual commandline tool

cmd/go-sqlite3/main.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	_ "github.com/mattn/go-sqlite3"
+	"log"
+	"os"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		log.Fatal("not enough arguments")
+	}
+	path := os.Args[1]
+	query := os.Args[2]
+	db, err := sql.Open("sqlite3", path)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer db.Close()
+	runQuery(db, query)
+}
+
+func runQuery(db *sql.DB, query string) (err error) {
+	rows, err := db.Query(query)
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+	cols, err := rows.ColumnTypes()
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+	// http://go-database-sql.org/varcols.html
+	vals := make([]interface{}, len(cols))
+	for i, types := range cols {
+		vals[i] = new(sql.RawBytes)
+		fmt.Printf("%-50s\t", types.Name())
+		/* debugging...
+		        length, ok := types.Length()
+				if !ok {
+					length = 0
+				}
+				fmt.Printf("%s[%s]\t", types.DatabaseTypeName(), length)
+		*/
+	}
+	fmt.Printf("\n")
+	for rows.Next() {
+		if err := rows.Scan(vals...); err != nil {
+			log.Println(err)
+			return err
+		}
+		// Now you can check each element of vals for nil-ness,
+		// and you can use type introspection and type assertions
+		// to fetch the column into a typed variable.
+		for i, _ := range vals {
+			if vals[i] == nil {
+				fmt.Printf("%-50s\t", "NULL")
+			} else {
+				fmt.Printf("%-50s\t", vals[i])
+			}
+		}
+		fmt.Printf("\n")
+	}
+	if err := rows.Err(); err != nil {
+		log.Println(err)
+	}
+	return err
+}