I have some SQL in which I want to test whether a certain record exists. I initially tried
perform select from vote,file
where vote.file_id=file.file_id and vote.uid = userId and
file.basename=aBase[1];
with the idea of testing whether the item with given uid and basename was found. The compiler complained about an error at select. To make it compile I had to declare version and write:
select file.basename into version from vote,file ....
Can someone explain why the perform here failed? I have other seemingly identical code which works fine.
Thanks.
From PostGreSQL DOC, SEE http://www.postgresql.org/docs/9.1/static/plpgsql-statements.html
Note: One might expect that writing SELECT directly would accomplish
this result, but at present the only accepted way to do it is PERFORM.
A SQL command that can return rows, such as SELECT, will be rejected
as an error unless it has an INTO clause.
Related
I was creating a function following an example from a database class which included the creation of a temporary variable (base_salary) and using a SELECT INTO to calculate its value later.
However, I did not realize I used a different order for the syntax (SELECT ... FROM ... INTO base_salary) and the function could be used later without any visible issues (values worked as expected).
Is there any difference in using "SELECT ... FROM ... INTO" syntax order? I tried looking about it in the PostgreSQL documentation but found nothing about it. Google search did not provide any meaningful information neither. Only thing I found related to it was from MySQL documentation, which only mentioned about supporting the different order in an older version.
There is no difference. From the docs of pl/pgsql:
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.
Notice that in (non-procedural) SQL, there is also a SELECT INTO command which works like CREATE TABLE AS, in this version the INTO must come right after the SELECT clause.
I always use SELECT ... INTO ... FROM , I believe that is the standard supported notation
https://www.w3schools.com/sql/sql_select_into.asp
I would recommend using this, also if there are any updates or if the other version might become unsupported as you mentioned...
I'm playing around with a DB and I'm generating random data to test my frontend. Everytime I wish to set every row a certain way I write
UPDATE medley
SET option = true
At this point Datagrip complains about a missing WHERE clause warning me that my query will update the whole table. But that's what I want!
Is there any generic WHERE clause that I can use like WHERE any?
For now I've added an ID so that I can WHERE id >= 0 but I was curious if there were any alternatives.
In DataGrip, there is a settings you need to change.
It will prevent you from running these queries and also show you the warning beforehand.
Unsafe query: Update statement without where clause updates all table rows
You will get the error: Error code: 1175 because you are using the safe mode.
To disable the safe mode:
toggle the option in Preferences -> SQL Editor and reconnect
You can add a where clause that is always true:
UPDATE medley
SET option = true
WHERE true;
After you run this kind of query, there are options to Execute and Execute and supress
I have a generic code that is used to retrieve DDL information from a Firebird database (FB2.1). It generates SQL code like
SELECT * FROM MyTable where 'c' <> 'c'
I cannot change this code. Actually, if that matters, it is inside Report Builder 10.
The fact is that some tables from my database are becoming a litle too populated (>1M records) and that query is starting to take too long to execute.
If I try to execute
SELECT * FROM MyTable where SomeIndexedField = SomeImpossibleValue
it will obviously use that index and run very quickly.
Well, it wouldn´t be that hard to the database find out that that is an impossible matcher and make some sort of optimization and avoid testing it against each row.
Is there any way to make my firebird database to optimize that search?
As the filter condition is a negative proposition (and also doesn't refer a column to search, but only a value to compare to another value), Firebird need to do a full table scan (without use any index) to confirm that aren't any record that meet your criteria.
If you can't change you need to wait for the upcoming 3.0 version, that will implement the Boolean data type, and therefore should start to evaluate "constant" fake comparisons in advance (maybe the client library will do this evaluation before send the statement to the server?).
I am using the DB2Driver in my code like
Class.forName("com.ibm.db2.jcc.DB2Driver");
and I am getting the result set in my java code which is scroll sensitive. my sql query look like this select distinct day , month , year from XXX . here table XXX is read only for the user which I am using ... so it is giving the following error
com.ibm.db2.jcc.a.SqlException: DB2 SQL Error: SQLCODE=-243, SQLSTATE=36001, SQLERRMC=SQL_CURSH200C3, DRIVER=3.51.90 .. I know this is the problem of read only .. but when i try to execute the same query in db2 control center it is working
please help me out in this
PubLib is your friend :-)
SQL0243NSENSITIVE cursor <cursor-name> cannot be defined for the specified SELECT statement.
Explanation:
Cursor <cursor-name> is defined as SENSITIVE, but the content of the SELECT statement requires DB2 to build a temporary result table of the cursor, and DB2 cannot guarantee that changes made outside this cursor will be visible. This situation occurs when the content of the query makes the result table read-only. For example, if the query includes a join, the result table is read-only. In these cases, the cursor must be defined as INSENSITIVE or ASENSITIVE.
The statement cannot be processed.
User response:
Either change the content of the query to yield a result table that is not read-only, or change the type of the cursor to INSENSITIVE or ASENSITIVE.
If you can't change the cursor type, look in to the use of materialised queriey tables. These are like views but also provide temporary backing storage for the data so that it's not forced read-only by the query type.
Whether that will help in situations where you've forced the user to be read only, I'm not entirely sure but you may be able to have different permission on the materialised data and real data (unfortunately, I haven't done a lot of work with these, certainly none where permissions were locked down to read-only level).
I get the following error when running an sqr report on DB2:
SQL0100W - No row was found for FETCH, UPDATE or DELETE; or the result of a query is an empty table. SQLSTATE=02000
The sql in question runs correctly when I paste it into RapidSQL, replacing the parameters. The sql in question is an insert-select. No rows are returned by the select, and this is fine... I expect the report to be blank for my parameters.
Any idea how I can get around this?
DB2 returns always an SQL0100 warning (this is a warning, not an error - errors would have negative values) when no rows are returned. That's the way it is.
I don't know peoplesoft at all - so I can't give you any pointers with that. Back when I was programming for DB2 we ignored those SQL0100 warnings.
If SQR can't gracefully handle a NOT_FOUND SQL0100 return, then code a preliminary query to return a count of the number of rows that satisfy the conditions of the actual query. Check the result of the count in an if-then block in SQR to run the actual query if and only if the row count returned by the preceding query was not zero.
Turns out to be an environment setup issue. Got resolved with no change from me after a couple of builds....
Strange :-/
if you delete delete more than one record using logic operation like delete from tabname where columnnmae=deleterecord and columnnmae=deleterecord then they show this type error.machine an