I have to perform lexical analysis on the oracle query and separate the query to various parts (based on the clauses)in perl. For example,Consider :
Select deleteddate,deletedby from temptable where id = 10;
I need to print
select : deleteddate , deletedby
from : temptable
where : id = 10
I used this code snippet :
my $parser= SQL::Statement->new();
$parser->{PrinteError}=1;
my $query = SQL::Statement->new("select deleteddate,deletedby from temptable where id =10",$parser);
my #columns = $query->columns();
print $columns[0]->name();
Though this prints deleteddate, this fails when i give a subquery inside the select clause:
Select deleteddate,deletedby,(select 1+1 from dual) from temptable where id = 10;
Can you please point me in the correct direction.
Thanks.
It looks to be a limitation of that package; it seems to be a general purpose parser and not something that can understand advanced features like subqueries or Oracle-specific constructs like "from dual".
What are the constraints of your system? If python is an option it looks like this is a more fully-featured library:
http://code.google.com/p/python-sqlparse/
The other option would be to use the actual Oracle database, if that's an option. You would:
use the DBI and DBD::Oracle modules to create a connection to Oracle & get a database handle,
create a statement handle by calling prepare() on the database handle using your query,
execute the query (there may be an option in Oracle to execute in "test only" or "parse only" mode),
examine the statement handle (such as the NAMES_hash property) to get the column names.
Otherwise it seems the SQL::Statement module unfortunately just isn't up to the task...
Related
I am using the new scripting feature of Big Query to declare a variable and then am using that variable in a standard SQL query.
The structure of the query is :
DECLARE {name of variable} {data type};
SET {name of variable} = {Value}'
(A SQL QUERY THEN FOLLOWS USING THE ABOVE VARIABLE)
I understand that this is now a script a no longer a typical query, and thus when I run it, it runs as a sequence of executable tasks. But is there anyway in the script to explicitly state that I only want to output the resulting table of the SQL query as opposed to both the result of declaring the variable and SQL query?
What BQ Outputs
Depending on how you "capture" the output, if you are sending a query from Python/Java/CLI, then the last SELECT statement in script is the only output that you receive with the API.
Please also note that each "output" that you see come with a cost/bytes-billed, which is another reason for them to be visible at all time.
Update:
If you need to capture the output of SELECT statement to a table, depending on your intention, you may use:
CREATE OR REPLACE TABLE <your_destination_table> AS SELECT ...
or
INSERT INTO TABLE <your_destination_table> SELECT ...
I'm reading sql code which has a line that looks like this:
SELECT INTO _user tag FROM login.user WHERE id = util.uuid_to_int(_user_id)::oid;
What exactly does this do? The usual way to use SELECT INTO requires specifying the columns to select after the SELECT token, e.g.
SELECT * INTO _my_new_table WHERE ...;
The database is postgresql.
This line must appear inside of a PL/pgSQL function. In that context the value from column tag is assigned to variable _user.
According to the documentation:
Tip: Note that this interpretation of SELECT with INTO is quite different from PostgreSQL's regular SELECT INTO command, wherein the INTO target is a newly created table.
and
The INTO clause can appear almost anywhere in the SQL command. Customarily it is written either just before or just after the list of select_expressions in a SELECT command, or at the end of the command for other command types. It is recommended that you follow this convention in case the PL/pgSQL parser becomes stricter in future versions.
I'm attempting to write an extension for SQL Developer to better support Postgres. These are just XML configuration files with SQL snippets in them. To display the values for a postgres sequence, I need to run a simple query of the following form:
select * from schema.sequence
The trouble with this is that the Oracle SQL Developer environment provides the correct schema and node (sequence) name as bind variables. This would mean that I should format the query as:
select * from :SCHEMA.:NAME
The trouble with this is that bind variables are only valid in the select clause or the where clause (as far as I'm aware), and using this form of the query returns a "syntax error at or near "$1" error message.
Is there a way to return the values in the sequence object without directly selecting them from the sequence? Perhaps some obtuse joined statement from pg_catalog tables?
Try this:
select *
from information_schema.sequences
where sequence_name = :name
and sequence_schema = :schema;
It's not exactly the same thing as doing a select from the sequence, but the basic information is there.
This should be stupidly simple to answer, but for the life of me I cannot find a definitive answer on this.
Can you use "?" in postgres, like you can in other database engines?
For example:
SELECT * FROM MyTable WHERE MyField = ?
I know I can use the $n syntax for this, for example from psql this works:
CREATE TABLE dummy (id SERIAL PRIMARY KEY, value INT);
PREPARE bar(int) AS INSERT INTO dummy (value) VALUES ($1);
EXECUTE bar(10);
SELECT * FROM DUMMY;
But if I try to prepare a statement using "?", eg.
PREPARE bar(int) AS INSERT INTO dummy (value) VALUES (?);
I get:
ERROR: syntax error at or near ")"
LINE 1: PREPARE bar(int) AS INSERT INTO dummy (value) VALUES (?);
...and yet, in various places I read that "postgres supports the ? syntax".
What's going on here? Does postgres support using ? instead of $1, $2, etc.
If so, how do you use it?
Specifically, this is making my life a pain porting a bunch of existing sql server queries to postgres, and if I can avoid having to rewrite all the where conditions an all of the sql statements that would be very, very nice.
SQL-level PREPARE in PostgreSQL does not support the ? placeholder, it uses the $1 ... $n style.
Most client libraries support the standard placeholders used by that language in parameterized queries, eg PgJDBC uses ? placeholders.
If you're sending your queries via a client library like nPgSQL, psqlODBC, PgJDBC, psycopg2, etc then you should be able to use the usual placeholders for that language and client.
in MS-SQL I can do something like this
#myVar AS int;
#myVar = 12;
SELECT * FROM table WHERE field = #myVar;
this totally bombs out in DB2 - and I'm not sure if it's RDBMS specific or if it's because I've FUBAR'd the syntax...
Any help is appreciated
there are a limited number of things you can do dynamically in db2 sql compared to ms-sql. most of the syntax for what you appear to be attempting is reserved for use only in a procedure in db2. see the documentation here http://publib.boulder.ibm.com/infocenter/db2luw/v9r5/topic/com.ibm.db2.luw.sql.ref.doc/doc/r0004240.html for what you can do dynamically in db2.
if you are ok supplying parameter value on the fly just use
select * from table where field = ?; when you run it, it will ask you to supply a value for the parm.
If you are using ADO.NET Data Provider to connect to the DB2 Express-C, you can prefix bound SQL parameters with #.
I'm not sure about other DB2 environments, but common symbols used in other databases are: : and ?, so it might be worth trying one of those.