startet with connection query intermediates

src/sql/condition.cpp

@@ -0,0 +1,26 @@
+#include "matador/sql/condition.hpp"
+
+namespace matador::sql {
+
+condition<column, placeholder, std::enable_if<true>::type>::condition(const column &fld, basic_condition::operand_t op, const placeholder &val)
+: basic_column_condition(fld, op)
+, value(val)
+{ }
+
+std::string condition<column, placeholder, std::enable_if<true>::type>::evaluate(dialect &d) const {
+  d.add_host_var(field_.name());
+  return d.prepare_identifier(field_.name()) + " " + operand + " " + d.next_placeholder();
+}
+
+condition<column, query>::condition(column col, basic_condition::operand_t op, query &q)
+: basic_column_condition(std::move(col), op)
+, query_(q)
+{}
+
+std::string condition<column, query>::evaluate(dialect &d) const {
+  std::string result(d.prepare_identifier(field_.name()) + " " + operand + " (");
+  result += (")");
+  return result;
+}
+
+}