Aggregating row data using user-defined aggregate in Informix IDS

Implementing mysql group_concat() aggregate in Informix IDS 11.5 - thanks to Jonathan Leffler.

As DBA do:

CREATE FUNCTION gc_init(dummy varchar(255)) RETURNING LVARCHAR;
    RETURN '';
END FUNCTION;

CREATE FUNCTION gc_iter(result LVARCHAR, value VARCHAR(255))
    RETURNING LVARCHAR;
    IF result = '' THEN
        RETURN TRIM(value);
    ELSE
        RETURN result || ',' || TRIM(value);
    END IF;
END FUNCTION;

CREATE FUNCTION gc_comb(partial1 LVARCHAR, partial2 LVARCHAR)
    RETURNING LVARCHAR;
    RETURN partial1 || ',' || partial2;
END FUNCTION;

CREATE FUNCTION gc_fini(final LVARCHAR) RETURNING LVARCHAR;
    RETURN final;
END FUNCTION;

CREATE AGGREGATE group_concat
    WITH (INIT = gc_init, ITER = gc_iter,
          COMBINE = gc_comb, FINAL = gc_fini);

Then you need to grant access to the functions to users that need it:

grant execute on function gc_init to appsql;
grant execute on function gc_iter to appsql;
grant execute on function gc_comb to appsql;
grant execute on function gc_fini to appsql;


Example Use:

select ord_id, group_concat(product)
from ord
group by ord_id

Aubit4GL: connecting to mysql and informix concurrently

Since database connections seems to be compile time, and you have to set A4GL_SQLTYPE in order to compile against database X - I wonder how you can open concurrent connections.. I cannot find any documentation on how to do this - but according to http://aubit4gl.sourceforge.net/aubit4gldoc/manual/html/features_summary.html it maybe that you have to use ODBC connections to each instead of native??

It seems that "open session" and "use session" can be used to dynamically switch at runtime. But compile time seems to be the kicker.. especially if you use "define x like table.column" in 4gl, unless it allows "define x like db.table.column" or searches both databases.

mysqldump to informix DS

Problem: Need to access mysql 5.0 data from 4js BDL (I4gl)

Solution attempts:

1. generate 4js dynamic VM with mysql support.. no mysql 5.0 support (only 4.x) and not forward compatible
2. try aubit4gl with mysql support.. no go.. see this
3. call script to unload mysql table and then load into informix

On solution attempt 3 - this proved more difficult than I first imagined.

I've been spoiled with Informix's very easy "unload to". Mysql simply has no equivalent. There is the "SELECT INTO OUTFILE", but (1) you need to "grant file on *.* to 'user'@'whateverhost'" (besides select permission of course), and (2) can be run from a remote host, but the output file is local to the mysql server instance.. and while you can use NFS, its a pain.

Also there is mysqldump - which I thought might do it.. but alas, if you use the --tab option it uses "SELECT INTO OUTFILE" internally anyway - plus you need to "grant lock tables on db.* to 'user'@'whateverhost'".

Ok - so had to revise my strategy - since I am running this script on remote host... this generates ansi "insert" statements that I will try to execute against informix:

mysqldump -h mysqlhost -usomeuser -psomepassword --compatible=ansi --no-create-info --compact dbname tablename > x.sql

Kinda works.. doesn't like text fields (clob datatype in informix).. and date formating could be an issue (easily fixed with informix DBDATE environment variable).. but certainly not as easy as I imagined.