query-builder: Add README

Signed-off-by: Sangwan Kwon <sangwan.kwon@samsung.com>

diff --git a/src/vist/query-builder/README.md b/src/vist/query-builder/README.md
new file mode 100644 (file)
index 0000000..0d370e2
--- /dev/null
+++ b/src/vist/query-builder/README.md
@@ -0,0 +1,152 @@
+# Query Builder to generate Type Safe Query
+Guarantee type safety by preventing type error 
+between sql query and sql schema at compile time.
+
+|   | ours | [sqlpp11](https://github.com/rbock/sqlpp11) | [sqlite_orm](https://github.com/fnc12/sqlite_orm) |
+|---|---|---|---|
+| **Tpye** | query builder | orm | orm |
+| **Language** | c++17 | c++11 ([WIP to c++17](https://github.com/rbock/sqlpp17)) | c++14 |
+| **Schema Location** | header file | header file | source file<br>(This makes hard to expose API.) |
+| **Intuition** | simple | complex | simple |
+| **Usability** | high | low | high |
+| **Backend** | sqlite3<br>(with virtual table) | mysql<br>sqlite3<br>(without virtual table)<br>postgresql<br>odbc | sqlite3<br>(without virtual table) |
+| **Feature** | basic(crud) | variety | variety |
+
+# Sample Code
+## ours
+```cpp
+/// header
+struct User {
+  int id;
+  std::string name;
+  int age;
+  
+  DECLARE_COLUMN(Id, "id", &User::id);
+  DECLARE_COLUMN(Name, "name", &User::name);
+  DECLARE_COLUMN(Age, "age", &User::Age);
+}
+
+DECLARE_TABLE(UserTable, "user", User::Id, User::Name, User::Age);
+
+/// source file
+UserTable.select(User::Id, User::Name, User::Age);
+/// => SELECT id, name, age FROM, user
+UserTable.insert(User::Id = 3, User::Name = "Tom", User::Age = 33);
+/// => INSERT INTO user (id, name, age) VALUES (3, 'Tom', 33)
+UserTable.update(User::Age = 36).where(User::Name == "Tom");
+/// => UPDATE user SET id = 3, name = 'Tom', age = 33 WHERE name = 'Tom'
+UserTable.remove().where(User::Name == "Tom");
+/// => DELETE FROM user WHERE name = 'Tom'
+```
+
+## sqlpp11
+```cpp
+/// header
+namespace TabSample_
+{
+  struct Alpha
+  {
+    struct _name_t
+    {
+      static constexpr const char* _get_name() { return "alpha"; }
+      template<typename T>
+        struct _member_t
+        {
+          T alpha;
+        };
+    };
+    using _value_type = sqlpp::bigint;
+    struct _column_type
+    {
+      using _must_not_insert = std::true_type;
+      using _must_not_update = std::true_type;
+      using _can_be_null = std::true_type;
+      using _trivial_value_is_null = std::true_type;
+      using _foreign_key = decltype(TabFoo::omega);
+    };
+   };
+
+  struct Beta
+  {
+    struct _name_t
+    {
+      static constexpr const char* _get_name() { return "beta"; }
+      template<typename T>
+        struct _member_t
+        {
+          T beta;
+        };
+    };
+    using _value_type = sqlpp::varchar;
+    struct _column_type
+    {
+      using _can_be_null = std::true_type;
+      using _trivial_value_is_null = std::true_type;
+      using _must_not_update = std::true_type;
+    };
+  };
+}
+
+struct TabSample: sqlpp::table_base_t<
+                  TabSample, 
+                  TabSample_::Alpha, 
+                  TabSample_::Beta>
+{
+  using _value_type = sqlpp::no_value_t;
+  struct _name_t
+  {
+    static constexpr const char* _get_name() { return "tab_sample"; }
+    template<typename T>
+      struct _member_t
+      {
+        T tabSample;
+      };
+  };
+  template<typename Db>
+    void serialize_impl(std::ostream& os, Db& db) const
+    {
+      os << _name_t::_get_name();
+    }
+};
+
+/// source code
+const auto t = test::TabBar{};
+select(all_of(t)).from(t).unconditionally());
+insert_into(t).set(t.gamma = true, t.beta = "kirschauflauf");
+update(t).set(t.delta = sqlpp::null).unconditionally();
+remove_from(t).where(t.beta != "transparent"), printer);
+```
+
+## sqlite_orm
+```cpp
+/// header
+struct User{
+  int id;
+  std::string firstName;
+  std::string lastName;
+  int birthDate;
+  std::unique_ptr<std::string> imageUrl;
+  int typeId;
+};
+
+/// source code
+auto table = make_table("users",
+                        make_column("id", &User::id, autoincrement(), primary_key()),
+                        make_column("first_name", &User::firstName),
+                        make_column("last_name", &User::lastName),
+                        make_column("birth_date", &User::birthDate),
+                        make_column("image_url", &User::imageUrl),
+                        make_column("type_id", &User::typeId));
+                        
+table.select(columns(&Employee::id, &Employee::name, &Employee::salary));
+table.insert(Employee{
+        -1,
+        "Allen",
+        25,
+        "Texas",
+        15000.00,
+});
+table.update_all(set(c(&Employee::address) = "Texas", c(&Employee::salary) = 20000.00),
+                 where(c(&Employee::age) < 30));
+
+```