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

Hanfei Shen <>
Mon May 2 18:15:35 CEST 2011


Hi,

I've tried https://github.com/dizzyd/erlang-mysql-driver, it works.

I'm installing unixodbc... Wait a minute. Thnx...


2011/5/3 Ingela Andin <>:
> 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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