2021-05-17 07:30:42 +00:00
|
|
|
#include <Functions/IFunction.h>
|
2018-09-08 01:24:09 +00:00
|
|
|
#include <Functions/FunctionHelpers.h>
|
|
|
|
#include <Functions/FunctionFactory.h>
|
|
|
|
#include <DataTypes/DataTypesNumber.h>
|
|
|
|
#include <DataTypes/DataTypeNullable.h>
|
|
|
|
#include <Core/ColumnNumbers.h>
|
|
|
|
#include <Columns/ColumnNullable.h>
|
|
|
|
|
|
|
|
|
|
|
|
namespace DB
|
|
|
|
{
|
2020-09-07 18:00:37 +00:00
|
|
|
namespace
|
|
|
|
{
|
2018-09-08 01:24:09 +00:00
|
|
|
|
|
|
|
/// Implements the function nullIf which takes 2 arguments and returns
|
|
|
|
/// NULL if both arguments have the same value. Otherwise it returns the
|
|
|
|
/// value of the first argument.
|
|
|
|
class FunctionNullIf : public IFunction
|
|
|
|
{
|
|
|
|
private:
|
2021-06-01 12:20:52 +00:00
|
|
|
ContextPtr context;
|
2018-09-08 01:24:09 +00:00
|
|
|
public:
|
|
|
|
static constexpr auto name = "nullIf";
|
|
|
|
|
2021-06-01 12:20:52 +00:00
|
|
|
static FunctionPtr create(ContextPtr context)
|
2018-09-08 01:24:09 +00:00
|
|
|
{
|
|
|
|
return std::make_shared<FunctionNullIf>(context);
|
|
|
|
}
|
|
|
|
|
2021-06-01 12:20:52 +00:00
|
|
|
explicit FunctionNullIf(ContextPtr context_) : context(context_) {}
|
2018-09-08 01:24:09 +00:00
|
|
|
|
|
|
|
std::string getName() const override
|
|
|
|
{
|
|
|
|
return name;
|
|
|
|
}
|
|
|
|
|
|
|
|
size_t getNumberOfArguments() const override { return 2; }
|
|
|
|
bool useDefaultImplementationForNulls() const override { return false; }
|
|
|
|
bool useDefaultImplementationForConstants() const override { return true; }
|
2021-06-22 16:21:23 +00:00
|
|
|
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
|
2018-09-08 01:24:09 +00:00
|
|
|
|
|
|
|
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
|
|
|
|
{
|
|
|
|
return makeNullable(arguments[0]);
|
|
|
|
}
|
|
|
|
|
2020-11-17 13:24:45 +00:00
|
|
|
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
|
2018-09-08 01:24:09 +00:00
|
|
|
{
|
2019-08-21 20:33:38 +00:00
|
|
|
/// nullIf(col1, col2) == if(col1 = col2, NULL, col1)
|
2018-09-08 01:24:09 +00:00
|
|
|
|
2020-10-19 15:27:41 +00:00
|
|
|
auto equals_func = FunctionFactory::instance().get("equals", context)->build(arguments);
|
|
|
|
auto eq_res = equals_func->execute(arguments, equals_func->getResultType(), input_rows_count);
|
2018-09-08 01:24:09 +00:00
|
|
|
|
2020-10-19 15:27:41 +00:00
|
|
|
ColumnsWithTypeAndName if_columns
|
|
|
|
{
|
|
|
|
{eq_res, equals_func->getResultType(), ""},
|
|
|
|
{result_type->createColumnConstWithDefaultValue(input_rows_count), result_type, "NULL"},
|
|
|
|
arguments[0],
|
|
|
|
};
|
2018-09-08 01:24:09 +00:00
|
|
|
|
2020-10-19 15:27:41 +00:00
|
|
|
auto func_if = FunctionFactory::instance().get("if", context)->build(if_columns);
|
|
|
|
auto if_res = func_if->execute(if_columns, result_type, input_rows_count);
|
2019-08-21 01:14:25 +00:00
|
|
|
|
2020-10-19 15:27:41 +00:00
|
|
|
return makeNullable(std::move(if_res));
|
2018-09-08 01:24:09 +00:00
|
|
|
}
|
|
|
|
};
|
|
|
|
|
2020-09-07 18:00:37 +00:00
|
|
|
}
|
2018-09-08 01:24:09 +00:00
|
|
|
|
|
|
|
void registerFunctionNullIf(FunctionFactory & factory)
|
|
|
|
{
|
|
|
|
factory.registerFunction<FunctionNullIf>(FunctionFactory::CaseInsensitive);
|
|
|
|
}
|
|
|
|
|
|
|
|
}
|
|
|
|
|