Error while using Null values in Tableau

[SergeiStradomsky]

Hi! We found some error, while using Null values in Tableau.

We get this error in release https://github.com/ClickHouse/clickhouse-odbc/releases/tag/v1.1.9.20201226, but
in release https://github.com/ClickHouse/clickhouse-odbc/releases/tag/v1.1.1.20191108 everything works just fine.

An error occurred while communicating with the Other Databases (ODBC) data source 'oroboros_test_123 (cubes)'
Bad Connection: Tableau could not connect to the data source.
Error Code: B19090E0
unknown type
SELECT SUM({fn CONVERT(NULL, SQL_BIGINT)}) AS sum_Calculation_3063644052176396288_ok
FROM oroboros_test_123
HAVING (COUNT(1) > 0)

This error occurs while creating Calculation Filed like IF FALSE THEN 1 END
How can we fix this?

UPD:
I changed some code here

clickhouse-odbc/driver/utils/type_info.h

Line 51 in 3c37dbd

throw std::runtime_error("unknown type");

, by replacing this line to throw std::runtime_error("unknown type. Got type " + type);
And got next message

An error occurred while communicating with the Other Databases (ODBC) data source 'cubes_clickhouse__fact_ue_partitioned_distributed (cubes)'
Bad Connection: Tableau could not connect to the data source.
Error Code: B19090E0
unknown type. Got type Nothing
SELECT SUM({fn CONVERT(NULL, SQL_BIGINT)}) AS sum_Calculation_3485082461064859648_ok
FROM cubes_clickhouse__fact_ue_partitioned_distributed
HAVING (COUNT(1) > 0)

As far as I can see, there is no type Nothing here

clickhouse-odbc/driver/utils/type_info.cpp

Line 7 in 3c37dbd

const std::map<std::string, TypeInfo> types_g = {

,
but there is type Nothing in Clickhouse doc https://clickhouse.tech/docs/ru/sql-reference/data-types/special-data-types/nothing/

[SergeiStradomsky]

Can anyone help with this?

[savelov]

Hi Sergei - you need to add mapping to TypeInfo with mapping to some SQL Type and number of bytes required to store it