2015-02-25 19:23 GMT+01:00 Aaron Cohen <aa...@assonance.org>:
> On Wed, Feb 25, 2015 at 1:08 PM, Cecil Westerhof <cldwester...@gmail.com>
> wrote:
>
>>
>>
>> 2015-02-25 18:14 GMT+01:00 Andy Fingerhut <andy.finger...@gmail.com>:
>>
>>> doseq does not have anything precisely like C/Java/Perl/etc.'s 'break'
>>> or 'continue'. The closest thing might be the :while keyword. You can see
>>> some one example of its use near the end of the examples on this page:
>>> http://clojuredocs.org/clojure.core/doseq
>>>
>>> The best way I know to get such behavior is to use Clojure's loop, where
>>> if/when/whatever-conditional-statements-you-wish can used to control
>>> explicitly to do another loop iteration using recur, or not.
>>>
>>
>> I made the following with loop:
>> (defn do-show-table
>> [table]
>> (loop [all-tables (show-tables db-spec)]
>> (let [this-table (get (first all-tables) :table_name)]
>> (if (= all-tables ())
>> (printf "Table not found: %s\n" table)
>> (if (= (lower-case table) (lower-case this-table))
>> (let [format "%-20s %-30s %-5s %-5s %-20s\n"]
>> (printf "Table %s:\n" table)
>> (printf format "Field" "Type" "Null?" "Key" "Default")
>> (doseq [{:keys [field type null key default]}
>> (jdbc/query db-spec [(str "SHOW COLUMNS FROM "
>> table)])]
>>
>
> Please don't get into the habit of doing db queries like this, you're one
> "Little Bobby Tables" away from an sql injection. In this case you should
> do (jdbc/query db-spec ["SHOW COLUMNS FROM ?" table]).
>
That gives:
JdbcSQLException Syntax error in SQL statement "SHOW COLUMNS FROM ?";
expected "identifier"; SQL statement:
SHOW COLUMNS FROM ? [42001-184] org.h2.engine.SessionRemote.done
(SessionRemote.java:622)
That is why I do it in this way. As I understood it this has to do with
that with a 'show columns from' the table can not be supplied. (I first
tried Yesql, only when that did not work I went to JDBC.)
> I think you would be well-served by a general clojure principle here of
> trying to get the data you're are dealing within into "values" as quickly
> as possible, and then working with those.
>
> Rather than inter-mixing your querying and display as you're doing here, I
> would design this as a query to fill some maps describing your tables, and
> then use clojure.pprint/print-table to print out the resulting map when
> desired.
>
This was just a proof of concept to get things working in the REPL. Later
on it should be done much neater. (For example a text
based version and a GUI version.)
> (printf format field type null key default))
>
>>
>> (println))
>> (recur (rest all-tables)))))))
>>
>> It solves both problems.
>>
>>
>> On Wed, Feb 25, 2015 at 8:59 AM, Cecil Westerhof <cldwester...@gmail.com>
>>> wrote:
>>>
>>>> At the moment I have the following function:
>>>> (defn do-show-table
>>>> [table]
>>>> (doseq [{:keys [table_name]} (show-tables db-spec)]
>>>> (when (= (lower-case table) (lower-case table_name))
>>>> (let [format "%-20s %-30s %-5s %-5s %-20s\n"]
>>>> (printf format "Field" "Type" "Null?" "Key" "Default")
>>>> (doseq [{:keys [field type null key default]}
>>>> (jdbc/query db-spec [(str "SHOW COLUMNS FROM
>>>> " table)])]
>>>> (printf format field type null key default))))))
>>>>
>>>> In this case it is not very important, because the outer sequence will
>>>> not be very big. But I would like to leave the doseq at the moment that the
>>>> when is executed. It will be done 0 or 1 times, so after it is done, there
>>>> is no use in continuing the sequence walk.
>>>>
>>>> The second part is that I would like to do an action if it is done 0
>>>> times after the doseq. Is this possible?
>>>>
>>>
--
Cecil Westerhof
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