ClickHouse/dbms/src/Functions/currentDatabase.cpp

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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <Interpreters/Context.h>
#include <DataTypes/DataTypeString.h>
namespace DB
{
class FunctionCurrentDatabase : public IFunction
{
const String db_name;
public:
static constexpr auto name = "currentDatabase";
static FunctionPtr create(const Context & context)
{
return std::make_shared<FunctionCurrentDatabase>(context.getCurrentDatabase());
}
explicit FunctionCurrentDatabase(const String & db_name) : db_name{db_name}
{
}
String getName() const override
{
return name;
}
size_t getNumberOfArguments() const override
{
return 0;
}
DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
{
return std::make_shared<DataTypeString>();
}
bool isDeterministic() const override { return false; }
void executeImpl(Block & block, const ColumnNumbers &, size_t result, size_t input_rows_count) override
{
block.getByPosition(result).column = DataTypeString().createColumnConst(input_rows_count, db_name);
}
};
void registerFunctionCurrentDatabase(FunctionFactory & factory)
{
factory.registerFunction<FunctionCurrentDatabase>();
}
}