I'm trying to use RJDBC to connect to a SAP HANA database and query for a temporary table, which is stored with a #-prefix:
test <- dbGetQuery(jdbcConnection,
"SELECT * FROM #CONTROL_TBL")
# Error in [...]: invalid table name: Could not find table/view #CONTROL_TBL in schema USER
If I execute the SQL statement in HANA, it works perfectly fine. I'm also able to query for permanent tables. Therefore I assume that R doesn't pass over the hashtag. Inserting escapes like "SELECT * FROM \\#CONTROL_TBL" however didn't solve my problem.
It's not possible to query for the data of a local or global temporary table from a different session, since they are by definition session-specific. In the case of a global temporary table one can query for the metadata of the table because they are shared across sessions.
Source: Tutorial for HANA temporary tables
You have to double-quote the table because it contains special characters, see SAP Help, identifiers for details.
test <- dbGetQuery(jdbcConnection,
'SELECT * FROM "#CONTROL_TBL"')
See also related discussion on stackoverflow.
Ok, local temporary tables are always only visible to the session in which they've been defined, while global temporary tables are visible just like normal tables, but the data is session private.
So, if you created the local temp. table (name starts with #) in a different session, then no wonder it cannot be found.
For your example, the question is: why do you need a temporary table in the first place?
Instead of that, you could e.g. define a view or a table function to select data from.
Related
I'm developing a Rust application for user registration via SSH (like the one working for SDF).
I'm using the SQLite3 database as a backend to store the information about users.
I'm opening the database file (or creating it if it does not exist) but I don't know the approach for checking if the necessary tables with expected structure are present in the database.
I tried to use PRAGMA schema_version for versioning purposes, but this approach is unreliable.
I found that there are posts with answers that are heavily related to my question:
How to list the tables in a SQLite database file that was opened with ATTACH?
How do I retrieve all the tables from database? (Android, SQLite)
How do I check in SQLite whether a table exists?
I'm opening the database file (or creating it if it does not exist)
but I don't know the approach for checking if the necessary tables
I found querying sqlite_master to check for tables, indexes, triggers and views and for columns using PRAGMA table_info(the_table_name) to check for columns.
e.g. the following would allow you to get the core basic information and to then be able to process it with relative ease (just for tables for demonstration):-
SELECT name, sql FROM sqlite_master WHERE type = 'table' AND name LIKE 'my%';
with expected structure
PRAGMA table_info(mytable);
The first results in (for example) :-
Whilst the second results in (for mytable) :-
Note that type is blank/null for all columns as the SQL to create the table doesn't specify column types.
If you are using SQLite 3.16.0 or greater then you could use PRAGMA Functions (e.g. pragma_table_info(table_name)) rather than the two step approach need prior to 3.16.0.
I am trying to connect to a table that is not in the sys schema. The code below works if sys.tablea exists.
conn <- dbConnect(dbDriver("MonetDB"), "monetdb://localhost/demo")
frame <- monet.frame(conn,"tablea")
If I define tablea in a different schema, e.g. xyz.tablea, then I get the error message
Server says 'SELECT: no such table 'tablea'' [#NA]
The account used to connect has rights to the table.
In a related question, is it possible to use camel-case from MonetDB.R? When I change the table name to TableA, the server again responds with
Server says 'SELECT: no such table 'tablea'' [#NA]
where the table name is all lower-case.
Using tables in other schemata is not possible with the current constructor of monet.frame. However, you can work around the issue as follows:
frame <- monet.frame(conn,"select * from xyz.tablea")
This trick also works with CamelCased table names.
For the next version, I am planning to fix the issue.
I need to add FTS to an existing database.
Started to test external content FTS tables, where the FTS indexes reside in the default (main) DB. Everything worked satisfactorily, except a few things (such as index rebuild) could take considerable amount of time.
Then I read about the possibility to put FTS index into attached DB. This seemed to promise several advantages, hence I decided to give it a try. However, all my trials failed. Here are a few examples:
Situation
We have a table 'account' with a text column 'code', and
Want to create FTS index for that column and place it into separate database file
Test1) ERROR: near ".": syntax error
ATTACH 'ZipFts.sdf' AS ZipFts; CREATE VIRTUAL TABLE ZipFts.account USING fts4(content=account, code);
INSERT INTO ZipFts.account(ZipFts.account) VALUES('rebuild');
Test 2) ERROR: Stack overflow (infinite recursion inside sqlite engine)
ATTACH 'ZipFts.sdf' AS ZipFts; CREATE VIRTUAL TABLE ZipFts.account USING fts4(content=account, code);
INSERT INTO ZipFts.account(account) VALUES('rebuild');
Test3) ERROR: no such table: ZipFts.account
ATTACH 'ZipFts.sdf' AS ZipFts; CREATE VIRTUAL TABLE ZipFts.ZipFts_account USING fts4(content="account", code);
INSERT INTO ZipFts_account(ZipFts_account) VALUES('rebuild');
Test4) ERROR: no such table: ZipFts.main.account
ATTACH 'ZipFts.sdf' AS ZipFts; CREATE VIRTUAL TABLE ZipFts.ZipFts_account USING fts4(content="main.account", code);
INSERT INTO ZipFts_account(ZipFts_account) VALUES('rebuild');
Does anybody know how these things work? Thanks in advance.
After some searching in sqlite3.c I found what might be the answer.
Look at the bottom of the function fts3ReadExprList(). The name of the content table is prefixed with the DB name here! This explains everything.
Moreover, this seems to be the only non-trivial use of zContentTbl (= the name of the content table). When I slightly modified fts3ReadExprList() function as shown in the code underneath, the problem disappeared.
// Code inserted by #JS-->
// Do not prefix zContentTbl with the database name. The table might reside in main database, for example.
if( p->zContentTbl){
fts3Appendf(pRc, &zRet, " FROM '%q' AS x", p->zContentTbl);
}
else
// <--#JS
fts3Appendf(pRc, &zRet, " FROM '%q'.'%q%s' AS x",
...
Note that I did not test the code sufficiently. (So far I only know that the FTS index was created.)
Anyway, for the time being, I consider this an SQLite bug and I'll try to go on with my fix.
I think this is as designed.
If it were otherwise, the underlying table for an external content table could change as databases are attached or detached.
You might be able to achieve this using a contentless FTS Table though.
Dan Kennedy.
Here's the situation. Due to the design of the database I have to work with, I need to write a stored procedure in such a way that I can pass in the name of the table to be queried against if at all possible. The program in question does its processing by jobs, and each job gets its own table created in the database, IE table-jobid1, table-jobid2, table-jobid3, etc. Unfortunately, there's nothing I can do about this design - I'm stuck with it.
However, now, I need to do data mining against these individualized tables. I'd like to avoid doing the SQL in the code files at all costs if possible. Ideally, I'd like to have a stored procedure similar to:
SELECT *
FROM #TableName AS tbl
WHERE #Filter
Is this even possible in SQL Server 2005? Any help or suggestions would be greatly appreciated. Alternate ways to keep the SQL out of the code behind would be welcome too, if this isn't possible.
Thanks for your time.
best solution I can think of is to build your sql in the stored proc such as:
#query = 'SELECT * FROM ' + #TableName + ' as tbl WHERE ' + #Filter
exec(#query)
not an ideal solution probably, but it works.
The best answer I can think of is to build a view that unions all the tables together, with an id column in the view telling you where the data in the view came from. Then you can simply pass that id into a stored proc which will go against the view. This is assuming that the tables you are looking at all have identical schema.
example:
create view test1 as
select * , 'tbl1' as src
from job-1
union all
select * , 'tbl2' as src
from job-2
union all
select * , 'tbl3' as src
from job-3
Now you can select * from test1 where src = 'tbl3' and you will only get records from the table job-3
This would be a meaningless stored proc. Select from some table using some parameters? You are basically defining the entire query again in whatever you are using to call this proc, so you may as well generate the sql yourself.
the only reason I would do a dynamic sql writing proc is if you want to do something that you can change without redeploying your codebase.
But, in this case, you are just SELECT *'ing. You can't define the columns, where clause, or order by differently since you are trying to use it for multiple tables, so there is no meaningful change you could make to it.
In short: it's not even worth doing. Just slop down your table specific sprocs or write your sql in strings (but make sure it's parameterized) in your code.
I currently have multiple queries that query data from a few tables linked through ODBC, and some temporary tables that are edited through the user interface. I have complex criteria in my queries such as:
SELECT * from ThingsData
WHERE (Thing In(SELECT Thing from ListOfThings) AND getThingFlag() = True);
In this case Thing is a field and ListOfThings is a temporary table that the user defines from the user interface. Basically, the user puts together a list of the field Thing that he/she wants to filter the data based on and I want to query only the data that matches the Thing values that the user adds to his/her list. Currently, the data I am querying is in the linked ODBC table, and the temp table ListOfThings is just a regular, local table and everything works peachy. I want to get rid of the linked table and use a pass through query instead. However, when i do that, unless the criteria is incredibly simplistic, i get an error:
"ODBC--Call Failed. Invalid object name ListOfThings."
If I dont have any criteria it works fine.
Long story short: In a pass through query, how do I apply criterias that include SELECTs and functions from my modules and just basically filter the pass through table based on data from my local tables?
What is at the other end of that ODBC link? In a pass-through query you will have to honor the syntax required by the database server, not Access syntax. I would first suspect that you can't have mixed case table names and I would try listofthings as the name.
If you have a tool that can be used to test queries directly against the database server, get the query working there and then simply cut and paste it into an Access pass-through query.