Thanks. The application is for an energy conservation application.
The 'a' table defines spaces to be controlled, the 'b' tables the
control schedules and parameters.
It would not be unreasonable to assume the 'a' table has >100 rows.
Each row in the 'a' table is associated with 3 'b' tables, all the names
known in advance and created off line at the same time as the row in the
'a' table.
Each 'b' table has up to 1,440 rows.
The application will loop through the 'a' table, recover a row from the
target 'b' table and execute it on the space described in the 'a' table.
Users can edit (add or delete rows) in the 'b' tables, but nothing else.
There are also 'c' and 'd' tables.
I could do this by composing queries outside sqlite. But that doesn't
seem very elegant and more error prone.
Because the 'a' table looks a lot like the sqlite_master table, I
thought there might be a way do do it all in an sql script.
On 02/24/2015 06:12 PM, R.Smith wrote:
> There's been many discussions on this topic, you can search for it, but
> I will try to recap in short:
>
> SQL does not work like this, not in SQLite or any other SQL engine may
> an entity construct be referenced by an uncontrolled data value. Of
> course it is easy to get around this in code whereby you can read a
> table name from one DB and use it in an SQL statement for any DB, but
> the onus here is on the maker of such software to implement whatever
> safety checks are needed to prevent corruption or indeed SQL injections
> and other mischief made possible by vulnerabilities exposed in this way.
>
> What you are trying here is not possible in pure SQL by design.
>
> There may however be other ways of achieving your goals, maybe
> explaining to us what you would like to do in a system/setup like this
> will help - surely someone here have done some similar thing before and
> they are always glad to assist.
>
>
> On 2015-02-24 11:37 PM, russ lyttle wrote:
>> I got the "Using SQLite" book and didn't find the answer there, or in a
>> Google, DuckDuckGo, or Gigiblast search.
>> I'm trying to create a field in a table to hold the name of a second
>> table, then retrieve that name for use.
>> The code below is the simplest of all the things I've tried. Can anyone
>> say what should be done so (10.) returns the same as (8.)?
>> Thanks
>>
>> 1. sqlite> CREATE TABLE a (id INTEGER PRIMARY KEY, name VARCHAR(16),
>> anotherTable TEXT);
>> 2. sqlite> SELECT * FROM sqlite_master;
>> table|a|a|2|CREATE TABLE a (id INTEGER PRIMARY KEY, name
>> VARCHAR(16), anotherTable TEXT)
>> 3. sqlite> INSERT INTO a (name, anotherTable) VALUES ('table1', 'b');
>> 4. sqlite> SELECT * FROM a;
>> 1|table1|b
>> 5. sqlite> CREATE TABLE b (id INTEGER PRIMARY KEY, name VARCHAR(16),
>> data FLOAT);
>> 6. sqlite> INSERT INTO b (name, data) VALUES ('B1', 35.0);
>> 7. sqlite> INSERT INTO b (name, data) VALUES ('B2', 40.0);
>> 8. sqlite> SELECT * FROM b;
>> 1|B1|35.0
>> 2|B2|40.0
>> 9. sqlite> SELECT anotherTable FROM a WHERE name='table1';
>> b
>> 10. sqlite> SELECT * FROM (SELECT anotherTable FROM a Where
>> name='table1');
>> b
>> sqlite>
>>
>>
>>
>>
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>
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