Can Any one please let me know Difference between oracle function,procedures and PostgreSQL functions,Stored Procedures?
That question is too broad, but I'll try to enumerate some of the major differences:
They are written in different languages. Oracle has PL/SQL and Java, while with PostgreSQL you can use almost any language you want.
PostgreSQL's PL/pgSQL is a clone of PL/SQL, but there are significant differences.
The syntax of the CREATE FUNCTION and CREATE PROCEDURE statements is quite different:
PostgreSQL has the code as a string literal, Oracle doesn't.
The syntax for declaring function results differs quite a bit.
Both systems have set returning functions (Orable calls them “pipelined”), but the syntax is different.
Oracle has a huge body of libraries in its data dictionary that makes upgrades a pain, but is very useful for writing functions. PostgreSQL has little of that, you typically write Perl or Python functions to interact with the system.
Support for procedures has only recently been added to PostgreSQL (v11), so they are not feature-complete yet.
You cannot have transaction management in PostgreSQL functions, and you cannot have what Oracle calls an “autonomous transaction”
You can work around some of these restrictions to some extent, but it is not the same.
Oracle functions are executed in the user context of the owner by default, while in PostgreSQL the default is to run them in the user context of the invoker.
Related
I am not sure in case of Stored Procedures, if Postgresql treats static sql any differently from a query submitted as a quoted string.
When I create a stored procedure in PostgreSQL using static sql, there seems to be no validation of the table names and table columns or column types but when I run the procedure I get the listing of the problems if any.
open ref_cursor_variable for
select usr_name from usres_master;
-- This is a typing mistake. The table name should be users_master. But the stored procedure is created and the error is thrown only when I run the procedure.
When I run the procedure I (naturally) get some error like :
table usres_master - invalid table name
The above is a trivial version. The real procedures we use at work combine several tables and run to at least a few hundred lines. In PostgresQL stored procedure, is there no advantage to using static sql over dynamic sql i.e. something like open ref_cursor_variable for EXECUTE select_query_string_variable.
The static SQL should be preferred almost time - dynamic SQL should be used only when it is necessary
from performance reasons (dynamic SQL doesn't reuse execution plans). One shot plan can be better some times (and necessary).
can reduce lot of code
In other cases uses static SQL every time. Benefits:
readability
reuse of execution plans
it is safe against SQL injection by default
static check is available
The source of a function is just a string to Postgres. The main reason for this is the fact that Postgres (unlike other DBMS) supports many, even installable languages for functions and procedures. As the Postgres core can't possibly know the syntax of all languages, it can not validate the "inner" part of a function. To my knowledge the "language API" does not contain any "validate" method (in theory this would probably be possible though).
If you want to statically validate your PL/pgSQL functions (and procedures since Postgres 11) you could use e.g. https://github.com/okbob/plpgsql_check/
I'm new to pl/sql and my question is: is it possible to "compile" a script in sql plus or sql developer and give the file to other person in order to allow other to execute the code but not allowing them to read the code?
It sounds like you are talking about the Oracle wrap utility (a separate command-line application that is part of your Oracle client install and not a part of SQL Developer) or the dbms_ddl.wrap function which you could invoke from SQL Developer. These create obfuscated statements that will create a stored procedure (or package or function) that behaves normally but where the text in the data dictionary is not human readable. The wrap utility doesn't provide perfect security-- there are unwrapping tools and presentations on the internet that would let an attacker unwrap the code you hand them. And you can often figure out what the unwrapped code is really doing by looking at other data dictionary views (v$sql will show the unwrapped SQL statements that are executed for example) or by tracing a session.
It depends also of definition of the word give. You can store PL/SQL code in the database. Give users right to execute it, to see the source code of the package header, but not to see the source of package body. But of course DBAs can read it, They can also trace it (even if it is wrapped).
Also note that PL/SQL packages are wrapped in a different way than PL/SQL procedures. As of 11g packages are wrapped using simple one-to-one byte substitution. While for PL/SQL procedures, there is stored obfuscated bytecode of DIANA virtual machine. AFAIK there is no accessible unwrap for PL/SQL procedures, it is much harder to reverse engineer.
Is it possible to use or add parameters on a simple query without the need of creating stored procedures or function? Are Bind Variables possible without creating a stored procedures?
where are you running the code from? If your running from a language like Java / VB you would use a stored procedure or prepared statement.
If using from Sql *Plus terminal or other Sql UI
SQL> variable deptno number
SQL> exec :deptno := 10
SQL> select * from
emp where deptno = :deptno;
From a high level language like Java or VB use stored procedures, following is from the article you linked to so not sure why you are asking this?
In fact, the answer to this is actually quite simple. When you put
together an SQL statement using Java, or VB, or whatever, you usually
use an API for accessing the database; ADO in the case of VB, JDBC in
the case of Java. All of these APIs have built-in support for bind
variables, and it's just a case of using this support rather than just
concatenating a string yourself and submitting it to the database.
For example, Java has PreparedStatement, which allows the use of bind
variables, and Statement, which uses the string concatenation
approach. If you use the method that supports bind variables, the API
itself passes the bind variable value to Oracle at runtime, and you
just submit your SQL statement as normal. There's no need to
separately pass the bind variable value to Oracle, and actually no
additional work on your part. Support for bind variables isn't just
limited to Oracle - it's common to other RDBMS platforms such as
Microsoft SQL Server, so there's no excuse for not using them just
because they might be an Oracle-only feature.
Not sure why you are asking as this information is there on the site http://www.akadia.com/services/ora_bind_variables.html
Well, assuming you will perform queries using an external programming language, prepared statements will make the job.
See http://en.wikipedia.org/wiki/Prepared_statement
I am working on migration project of Oracle to Teradata.
The tables have been migrated using datastage jobs.
How do I migrate Oracle Views to Teradata?
Direct script copying is not working due to SQL statements difference of both databases
Please help?
The DECODE() Oracle function is available as part of the Oracle UDF Library on the Teradata Developer Exchange Downloads section. Otherwise, you are using the DECODE function in your example in the same manner in which the ANSI COALESCE() function behaves:
COALESCE(t.satisfaction, 'Not Evaluated')
It should be noted that the data types of the COALESCE() function must be implicitly compatible or you will receive an error. Therefore, t.satisfaction would need to be at least CHAR(13) or VARCHAR(13) in order for the COALESCE() to evaluate. If it is not, you can explicitly cast the operand(s).
COALESCE(CAST(t.satisfaction AS VARCHAR(13)), 'Not Evaluated')
If your use of DECODE() includes more evaluations than what is in your example I would suggest implementing the UDF or replacing it with a more standard evaluated CASE statement. That being said, with Teradata 14 (or 14.1) you will find that many of the Oracle functions that are missing from Teradata will be made available as standard functions to help ease the migration path from Oracle to Teradata.
Does anybody know if Common Table Expressions and User-defined functions (not from Java) are supported on Sybase 12.5? I'm trying but could not seem to make these work. Thanks guys.
Both are not supported by ASE 12.5
You can use stored procedure instead of functions. I am not sure about what you are referring to by saying common table expressions
Sorry I have to disagree. Microsoft SQL Server is based on Sybase 7.0. So there may not be Common Table Expressions and User-Defined Functions, there are equivalent ways to do the same thing.
For example CTE can be done either in nested queries or via temp tables using a number sign (#) in front of the table name.
For User Defined Functions, create a stored procedure with simple SQL code and call it via the exec function for example "exec my_sql_code". This allows nesting of stored procedures.
Good SQL, good night.