Correct example codes

Author: peter279k

README.md

@@ -34,46 +34,52 @@ $ make
 ## Example
 
 ```cpp
+#include <iostream>
 #include <clickhouse/client.h>
 
 using namespace clickhouse;
 
-/// Initialize client connection.
-Client client(ClientOptions().SetHost("localhost"));
+int main()
+{
+    /// Initialize client connection.
+    Client client(ClientOptions().SetHost("localhost"));
 
-/// Create a table.
-client.Execute("CREATE TABLE IF NOT EXISTS test.numbers (id UInt64, name String) ENGINE = Memory");
+    /// Create a table.
+    client.Execute("CREATE TABLE IF NOT EXISTS default.numbers (id UInt64, name String) ENGINE = Memory");
 
-/// Insert some values.
-{
-    Block block;
+    /// Insert some values.
+    {
+        Block block;
 
-    auto id = std::make_shared<ColumnUInt64>();
-    id->Append(1);
-    id->Append(7);
+        auto id = std::make_shared<ColumnUInt64>();
+        id->Append(1);
+        id->Append(7);
 
-    auto name = std::make_shared<ColumnString>();
-    name->Append("one");
-    name->Append("seven");
+        auto name = std::make_shared<ColumnString>();
+        name->Append("one");
+        name->Append("seven");
 
-    block.AppendColumn("id"  , id);
-    block.AppendColumn("name", name);
+        block.AppendColumn("id"  , id);
+        block.AppendColumn("name", name);
 
-    client.Insert("test.numbers", block);
-}
+        client.Insert("default.numbers", block);
+    }
 
-/// Select values inserted in the previous step.
-client.Select("SELECT id, name FROM test.numbers", [] (const Block& block)
-    {
-        for (size_t i = 0; i < block.GetRowCount(); ++i) {
-            std::cout << block[0]->As<ColumnUInt64>()->At(i) << " "
-                      << block[1]->As<ColumnString>()->At(i) << "\n";
+    /// Select values inserted in the previous step.
+    client.Select("SELECT id, name FROM default.numbers", [] (const Block& block)
+        {
+            for (size_t i = 0; i < block.GetRowCount(); ++i) {
+                std::cout << block[0]->As<ColumnUInt64>()->At(i) << " "
+                          << block[1]->As<ColumnString>()->At(i) << "\n";
+            }
         }
-    }
-);
+    );
 
-/// Delete table.
-client.Execute("DROP TABLE test.numbers");
+    /// Delete table.
+    client.Execute("DROP TABLE default.numbers");
+
+    return 0;
+}
 ```
 
 ## Thread-safety