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.
Related
I do not have sufficient privileges to use a CREATE statement, I can only SELECT. I have a script that has three distinct parts and calculations that need to run and each one references the same complicated WITH statement selection that redundantly clutters the code and is a pain to maintain in three separate locations.
I have tried creating temp tables and views, but again, privileges do not support. Is there a way using either SQL or PL/SQL syntax to define my WITH statement ONCE without using CREATE, and then reference it like I would any other table? Example:
--Define the temp table
WITH tempview AS (SELECT .... FROM ...);
--First query
SELECT ... FROM tempview;
/
--Second query
SELECT ... FROM tempview;
/
--Third query
SELECT ... FROM tempview;
/
Getting the correct permissions and creating permanent objects is the best approach. It sounds like this view would only be used in a single script, which doesn't necessarily make it any less valid to create it, but you might find it harder to justify depending on your DBA and policies. It's certainly worth trying that approach, as #DCookie suggested.
If that fails then there may be hacky workarounds, depending on the client you will run this script in.
For instance, in SQL*Plus it's possible to abuse substitution variables to get something close to what you describe. This uses the define command to create a substitution variable that contains the 'view' query, and then uses that variable inside a WITH clause. (You can't replace the entire with like this, but it's maybe clearer like this anyway). I'm used a trivial dummy query:
define tempview_query = 'SELECT * -
FROM dual -
UNION ALL -
SELECT * -
FROM dual'
WITH tempview AS (&tempview_query)
SELECT * FROM tempview;
WITH tempview AS (&tempview_query)
SELECT * FROM tempview;
When the script is run the output produced is:
D
-
X
X
2 rows selected.
D
-
X
X
2 rows selected.
I've also executed set verify off to hide the substitutions, but turning it on might be instructive to see what's happening.
Notice the dashes at the end of each line of the query; that's the continuation character, and as the define docs mention:
If the value of a defined variable extends over multiple lines (using the SQL*Plus command continuation character), SQL*Plus replaces each continuation character and carriage return with a space.
so the 'new' query shown by set verify on will have your entire view query on a single line (if you display it). It's feasible that with a long enough query you'd hit some line length limit but hopefully you won't reach that point (except you did; see below).
You can do the same thing in SQL Developer, but there the continuation needs to use two dashes, so:
define tempview_query = 'SELECT * --
FROM dual --
UNION ALL --
SELECT * --
FROM dual'
except it isn't quite the same as the continuation in SQL*Plus; here the define has to end with a dash, but it is not replaced in the way the SQL*Plus docs describe - so with a single dash the define works but the query ends up invalid. (At least in 4.2.0; possibly a bug...) By using two dashes the multi-line define still works, the dashes remain part of the query, but they're treated as comment markers; so they make the substituted query look odd (again, if you display it) but don't stop it working. You won't notice with set verify off unless someone looks in v$sql.
If your query exceeds 240 characters - which is rather likely unless it's trivial enough to repeat anyway - you'll hit something like:
string beginning "'SELECT * ..." is too long. maximum size is 240 characters.
Both SQL*Plus and SQL Developer allow you to set a substitution variable from a query, using the column ... new_value command:
column tempalias new_value tempview_query
set termout off
select q'[SELECT *
FROM dual
UNION ALL
SELECT *
FROM dual]'
FROM dual;
set termout on
The query selects the text of your view query as a string; I've used the alternative quoting mechanism, with [] as the delimiters, so you don't have to escape any single quotes in the view query. (You need to pick a delimiter that can't appear in the query too, of course). Also note that you don't need the line continuation character any more.
The text literal that query generates is aliased as tempalias. The column command sets the tempview_query substitution variable to whatever that aliased column expression contains. Using the substitution variable is then the same as in the previous examples.
WITH tempview AS (&tempview_query)
SELECT * FROM tempview;
The set termout lines just hide that generating query; you can temporarily omit the off line to see what the query produces, and that it does exactly match the view query you expected.
Other clients might have similar mechanisms, but those are the only two I'm really familiar with. I should probably also reiterate that this is a bit of a hack, and not something I'd necessarily recommend...
Another trick with SQL*Plus is to import code from a second SQL script. You can do this with the # command (making sure to put the # at the very start of a line), e.g.:
tempview.sql
WITH tempview AS (SELECT .... FROM ...)
(notice there is no ending semicolon ; here, and make sure you either don't have a blank line at the end of the file or set sqlblanklines on)
main.sql
--First query
#tempview.sql
SELECT ... FROM tempview
/
--Second query
#tempview.sql
SELECT ... FROM tempview
/
--Third query
#tempview.sql
SELECT ... FROM tempview
/
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.
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...
I am writing a database abstraction layer that also abstracts some of the different query types. One of them is called "field_exists" - its purpose should be pretty self-explanatory.
And I want to implement that for SQLite.
The problem I am having is that I need to use one query that either returns a row confirming that the field exists or none if it doesn't. Thus, I cannot use the PRAGMA approach.
So, what query can I use to check whether a field exists in SQLite, that fulfills the above criteria?
EDIT: I should add that the query needs to be able to run in PHP code (using PDO).
Also, the query should look something like this (which only works with MySQL):
SHOW COLUMNS FROM table LIKE 'field'
Trying to select a field that doesn't exist will return an exception, then you can catch it and return nothing.
Use the .schema TABLENAME command. It will tell you the command that was issued to create the table. For more info chekcout the SQLite command shell documentation.
If you don't have access to the sqlite command line, you can always query the sqlite_master table. Let's say you want to know the command used to create the table MyTable. You'd issue this:
select sql from sqlite_master where name='MyTable';
This then gives you the sql command that was used to create the table. Then just grep through that output and see if the column you're looking for is in the command used to create the table.
UPDATE 2:
Actually better than the sql I posted above, you can use this:
PRAGMA table_info(*table_name*)
This will show you all the columns in a given table along with their types and other info.
Normally, I call my function like so:
SELECT *
FROM TABLE(
package_name.function(parameters)
)
I'm trying to call this function across a database link. My intuition is that the following is the correct syntax, but I haven't gotten it to work:
SELECT *
FROM TABLE(
package_name.function#DBLINK(parameters)
)
> ORA-00904: "PACKAGE_NAME"."FUNCTION": invalid identifier
I've tried moving around the database link to no effect. I've tried putting it after the parameter list, after the last parenthesis, after the package name...I've also tried all of the above permutations including the schema name before the package name. I'm running out of ideas.
This is oracle 10g. I'm suspicious that the issue may be that the return type of the function is not defined in the schema in which I'm calling it, but I feel like I should be getting a different error if that were the case.
Thanks for your help!
What you're trying is the correct syntax as far as I know, but in any case it would not work due to the return type being user-defined, as you suspect.
Here's an example with a built-in pipelined function. Calling it locally works, of course:
SELECT * FROM TABLE(dbms_xplan.display_cursor('a',1,'ALL'));
Returns:
SQL_ID: a, child number: 1 cannot be found
Calling it over a database link:
SELECT * FROM TABLE(dbms_xplan.display_cursor#core('a',1,'ALL'));
fails with this error:
ORA-30626: function/procedure parameters of remote object types are not supported
Possibly you are getting the ORA-904 because the link goes to a specific schema that does not have access to the package. But in any case, this won't work, even if you define an identical type with the same name in your local schema, because they're still not the same type from Oracle's point of view.
You can of course query a view remotely, so if there is a well-defined set of possible parameters, you could create one view for each parameter combination and then query that, e.g.:
CREATE VIEW display_cursor_a_1_all AS
SELECT * FROM TABLE(dbms_xplan.display_cursor('a',1,'ALL'))
;
If the range of possible parameter values is too large, you could create a procedure that creates the needed view dynamically given any set of parameters. Then you have a two-step process every time you want to execute the query:
EXECUTE package.create_view#remote(parameters)
SELECT * FROM created_view#remote;
You have to then think about whether multiple sessions might call this in parallel and if so how to prevent them from stepping on each other.