[erlang-questions] Erlang and MySQL: ODBC, Column type not supported

Ingela Andin <>
Mon May 2 18:08:10 CEST 2011


Hi!

Well the best thing would be if you can provide me with a way to reproduce it.
Do you have the possibility to try another odbc-driver with your database?

Regards Ingela Erlang/OTP team - Ericsson AB


2011/5/2 Hanfei Shen <>:
> Hi,
>
> I had changed the type from SQLINTEGER to SQLSMALLINT, but the problem
> is still there...
>
> (gdb) i func encode_data_type
> File odbcserver.c:
> static void encode_data_type(SQLSMALLINT, SQLINTEGER, SQLSMALLINT, db_state *);
>
> Breakpoint 1, encode_data_type (sql_type=-9, size=255,
> decimal_digits=0, state=0x7fffa5380210) at odbcserver.c:1396
> 1396        switch(sql_type) {
>
> Do you need any details?
>
> 2011/5/2 Ingela Anderton Andin <>:
>> Hi!
>>
>> Hanfei Shen wrote:
>>>
>>> Hi Ingela,
>>>
>>> Did you mean the value of variable "sql_type"?
>>>
>>>
>>
>> Yes.
>>
>>> I tried to inspect it through gdb, setting a break on func
>>> encode_data_type. And then I got:
>>>
>>> Breakpoint 1, encode_data_type (sql_type=-9, size=255,
>>> decimal_digits=0, state=0x7fffc657ec40) at odbcserver.c:1396
>>> 1396        switch(sql_type) {
>>>
>>>
>>
>> Well that is defenetly not a good value. Looking at the code just now
>> I noticed that
>>
>> encode_data_type defines sql_type as "SQLINTEGER sql_type" and it
>> ought to be "SQLSMALLINT sql_type". If you change that does it fix your
>> problem?
>>
>> Regards Ingela Erlang/OTP team - Ericsson AB
>>
>>
>>
>>> 2011/5/2 Ingela Andin <>:
>>>
>>>>
>>>> Hi!
>>>>
>>>> The erlang odbc application supports {sql-varchars,  N} where N = 255
>>>> in your case. The return values
>>>> you get suggest that the odbc-driver you have returns an unexpected
>>>> column type.
>>>>
>>>> In the erlang odbc port program there is a switch that handles type
>>>> when describing a coloumn that if we take out
>>>> the handling code looks like this.
>>>>
>>>> switch(sql_type) {
>>>>   case SQL_CHAR:
>>>>   case SQL_VARCHAR:
>>>>   case SQL_WCHAR:
>>>>   case SQL_WVARCHAR:
>>>>   case SQL_NUMERIC:
>>>>   case SQL_DECIMAL:
>>>>   case SQL_INTEGER:
>>>>   case SQL_TINYINT:
>>>>   case SQL_SMALLINT:
>>>>   case SQL_REAL:
>>>>   case SQL_FLOAT:
>>>>   case SQL_DOUBLE:
>>>>   case SQL_BIT:
>>>>   case SQL_TYPE_DATE:
>>>>   case SQL_TYPE_TIME:
>>>>   case SQL_TYPE_TIMESTAMP:
>>>>   case SQL_BIGINT:
>>>>   case SQL_BINARY:
>>>>   case SQL_LONGVARCHAR:
>>>>   case SQL_VARBINARY:
>>>>   case SQL_LONGVARBINARY:
>>>>   case SQL_INTERVAL_MONTH:
>>>>   case SQL_INTERVAL_YEAR:
>>>>   case SQL_INTERVAL_DAY:
>>>>   case SQL_INTERVAL_MINUTE:
>>>>   case SQL_INTERVAL_HOUR_TO_SECOND:
>>>>   case SQL_INTERVAL_MINUTE_TO_SECOND:
>>>>   case SQL_UNKNOWN_TYPE:
>>>>   default: /* Will probably never happen */
>>>>       ei_x_encode_atom(&dynamic_buffer(state), "ODBC_UNSUPPORTED_TYPE");
>>>>       break;
>>>>   }
>>>>
>>>>
>>>> And you end up in the default clause which is very unexpected and the
>>>> root to your problem.  If  you can figur out
>>>> what your driver returns for the ODBC C-API function SQLDescribeCol we
>>>> could know if the driver is at fault or if the odbc-port program is.
>>>>
>>>> Regards  Ingela Erlang/OTP team - Ericsson AB
>>>>
>>>> 2011/5/1 Hanfei Shen <>:
>>>>
>>>>>
>>>>> Dear all,
>>>>>
>>>>> I'm a newbie programming in erlang. When I used ODBC to connect to a
>>>>> MySQL database through Connector/ODBC (MyODBC), I got some error when
>>>>> calling odbc:sql_query(Conn, "SELECT * FROM action"):
>>>>>
>>>>> {error,"Column type not supported"}
>>>>>
>>>>> Then I call odbc:describe_table(Conn, "action"), it returned:
>>>>>
>>>>> {ok,[{"id",sql_integer},
>>>>>     {"code",'ODBC_UNSUPPORTED_TYPE'},
>>>>>     {"compliment_desc",'ODBC_UNSUPPORTED_TYPE'},
>>>>>     {"status_desc",'ODBC_UNSUPPORTED_TYPE'},
>>>>>     {"parameter",'ODBC_UNSUPPORTED_TYPE'},
>>>>>     {"cause",'ODBC_UNSUPPORTED_TYPE'},
>>>>>     {"disabled",sql_tinyint}]}
>>>>>
>>>>> And desc the table in mysql client:
>>>>> mysql> desc action;
>>>>>
>>>>> +-----------------+--------------+------+-----+---------+----------------+
>>>>> | Field           | Type         | Null | Key | Default | Extra
>>>>>  |
>>>>>
>>>>> +-----------------+--------------+------+-----+---------+----------------+
>>>>> | id              | int(11)      | NO   | PRI | NULL    | auto_increment
>>>>> |
>>>>> | code            | varchar(255) | NO   |     | NULL    |
>>>>>  |
>>>>> | compliment_desc | varchar(255) | NO   |     |         |
>>>>>  |
>>>>> | status_desc     | varchar(255) | NO   |     |         |
>>>>>  |
>>>>> | parameter       | varchar(255) | NO   |     |         |
>>>>>  |
>>>>> | cause           | varchar(255) | NO   | UNI |         |
>>>>>  |
>>>>> | disabled        | tinyint(1)   | NO   |     | 0       |
>>>>>  |
>>>>>
>>>>> +-----------------+--------------+------+-----+---------+----------------+
>>>>>
>>>>> It seems that Erlang ODBC driver does not support the mysql type
>>>>> varchar? How can I use the database without touching the db schema?
>>>>>
>>>>>
>>>>> Some details about the system env:
>>>>>
>>>>> $ uname -a
>>>>> Linux 2.6.36-gentoo-r8 #4 SMP Thu Apr 7 20:13:18 CST 2011 x86_64
>>>>> Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz GenuineIntel GNU/Linux
>>>>>
>>>>> $ erl
>>>>> Erlang R13B04 (erts-5.7.5) [source] [64-bit] [smp:2:2] [rq:2]
>>>>> [async-threads:0] [kernel-poll:false]
>>>>>
>>>>> $ emerge -vp erlang
>>>>> dev-lang/erlang-13.2.4  USE="doc kpoll odbc smp ssl -emacs -hipe -java
>>>>> -sctp -tk -wxwidgets"
>>>>>
>>>>> eshell> code:which(odbc).
>>>>> "/usr/lib64/erlang/lib/odbc-2.10.7/ebin/odbc.beam"
>>>>>
>>>>> $ mysql -V
>>>>> mysql  Ver 14.14 Distrib 5.1.51, for pc-linux-gnu (x86_64) using
>>>>> readline 5.1
>>>>>
>>>>> Server version: 5.1.51-log Gentoo Linux mysql-5.1.51
>>>>>
>>>>> $ emerge -vp myodbc
>>>>> dev-db/myodbc-5.1.6  USE="-debug -doc -qt4 -static"
>>>>>
>>>>>
>>>>> Any help will be greatly appreciated.  Thanks in advance.
>>>>> Sorry for my poor English, I'm not a native...
>>>>>
>>>>> Best,
>>>>>
>>>>> --
>>>>> Hanfei
>>>>> _______________________________________________
>>>>> erlang-questions mailing list
>>>>> 
>>>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>>>
>>>>>
>>>
>>>
>>
>>
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