#include #include #include #include namespace DB { namespace { /// Returns name of IColumn instance. class FunctionToColumnTypeName : public IFunction { public: static constexpr auto name = "toColumnTypeName"; static FunctionPtr create(const Context &) { return std::make_shared(); } String getName() const override { return name; } bool useDefaultImplementationForNulls() const override { return false; } size_t getNumberOfArguments() const override { return 1; } DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override { return std::make_shared(); } ColumnPtr executeImpl(ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override { return DataTypeString().createColumnConst(input_rows_count, arguments[0].column->getName()); } ColumnPtr getResultIfAlwaysReturnsConstantAndHasArguments(const ColumnsWithTypeAndName & arguments) const override { return DataTypeString().createColumnConst(1, arguments[0].type->createColumn()->getName()); } }; } void registerFunctionToColumnTypeName(FunctionFactory & factory) { factory.registerFunction(); } }