I have an oracle query which has a select statement
select table.columnname = ${sometext_sometext_sometext}
I would like to know what is the purpose of ${}.
Also this throws an error in Oracle SQL developer. Kindly advise what is the work around.
This isn't Oracle syntax, this is a common syntax for interpolating variables into a string found in Perl, Groovy, and a bunch of other languages.
You don't say what the context is here, but what is probably going on is something modifies the file, probably with environment-related properties, before the SQL gets run, the ${} is there to identify to the modifying script what value to substitute here. This is a common thing to do when you have environment-specific properties that need to be injected into a SQL script.
Can you give some background as to where you got this SQL statement? It appears that you are working with a query that requires pre-processing via Java, PHP, a Bash shell script, etc. Standard Oracle SQL or PL/SQL does not know what to do with the "${}" syntax.
I have used this syntax in a standard SQL template that I then process in Java or a bash shell script to generate the final SQL statement.
Related
I am trying to run the following Firebird SQL query in LibreOffice, which has embedded Firebird:
SELECT RDB$GET_CONTEXT('SYSTEM', 'ENGINE_VERSION') AS "VERSION"
FROM "RDB$DATABASE";
I get the message Syntax error in SQL statement. Can anyone tell me what I am doing wrong? This works in FlameRobin, but not in LibreOffice.
The error "Syntax error in SQL statement" is a HSQLDB error. So, first, make sure your LibreOffice Base project is actually created as a Firebird Embedded project.
I was able to reproduce the error in LibreOffice Base 6.4.4.2 with a Firebird Embedded project. It looks like LibreOffice first tries to parse the query using HSQLDB (probably to be able to transform HSQLDB syntax to Firebird syntax), and only then forwards it to Firebird.
The cause of the error is the $ in RDB$GET_CONTEXT which is not a valid character in an unquoted object name in the HSQLDB SQL syntax, while it is valid in the Firebird SQL syntax. Normally, double quoting the specific object name would solve this, but RDB$GET_CONTEXT is not actually a function, but a syntax construct, so it can't be quoted in Firebird.
To be able to execute this query, you need to enable the 'Run SQL command directly' option in the SQL View, either under Edit > 'Run SQL command directly', or using the 'Run SQL command directly' button in the toolbar (database icon with >_).
I have the following SQL script (all names replaced with metasyntactic variables):
DELETE FROM FOO
WHERE UPPER(BAR)=? AND UPPER(BAZ)=? AND UPPER(QUX)=? AND UPPER(QUUX)=? AND UPPER(CORGE)=?;
When I run it in SQL Developer, I get the following error, as expected: SQL Error: Missing IN or OUT parameter at index:: 1
Is there a way in SQL Developer to pass test parameters to these values (in this case, BAR, BAZ, QUX, QUUX, and CORGE) or do I have to manually replace the question marks? Thanks!
UPDATE: I've been looking on the internet to try to find the answer with no luck; none of the articles I found deal with the FOO=? syntax. I know that that is the proper syntax to access (and in this case, delete from) the database from a Java program, but I would like to test the SQL script before embedding it in the program.
A query that way is called a prepared statement. It is used as a way to send SQL statements from a program to the database.
First you have to prepare the prepared statement object and later you supply the parameters and finally execute the statement. When setting the parameters, you refer to each question mark in the order they apear in the statement. So in you case, BAR would be parameter 1 and CORGE will be parameter 5.
http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html
For testing a query like this is quite useless in my experience. You could change the paramters to variables or even substitution variables if that is more convenient while testing.
http://docs.oracle.com/cd/B19306_01/server.102/b14357/ch5.htm#i1211130
I've decided to use postgreSQL as database for a game project(C++).
At the moment I'm using Oracle and it's Pro*C precompiler at work and heard that postgreSQL also has something similar called ECPG.
It's also possible to access data from the the postgres database directly by using the SQL in a string.
So the difference between "normal" and using ECPG, is that you can write your SQL statements like code?, or are there any other differences I should be aware of?.
(PS: i know I'm using it at work, but I haven't noticed any other differences)
Looking forward to hearing from you guys.
Yes, ECPG is covered in the documentation.
So the difference between "normal" and using ECPG, is that you can
write your SQL statements like code?
Well, SQL statements are code. A SQL statement just looks like a SQL statement. This is what a CREATE TABLE statement might look like in ECPG.
EXEC SQL CREATE TABLE foo (number integer, ascii char(16));
ECPG allows variable substitution. (Maybe that's what you meant by "write your SQL statements like code".)
EXEC SQL INSERT INTO sometable VALUES (:v1, 'foo', :v2);
All this stuff is in the documentation.
3GLs provide mechanisms to prepare statements before executing them. E.g.
SELECT name
FROM people
WHERE age=:AGE
The same query can then be executed for different ages. But can such a statement also be prepared in a "plain" Oracle SQL client? Can the same be done in e.g. SQL Plus or dbForge Studio for Oracle as in Java or C# or any other programming language that supports prepared statements?
In dbForge Studio for Oracle, named parameters can be used, preceded by a colon :
SELECT *
FROM people
WHERE name=:name
The parameters can then be filled in with the "Edit parameters dialog box", available from the SQL toolbar.
I know you didn't ask about PostgreSQL but about Oracle. However, of note, PostgreSQL has this feature right in its SQL language.
The SQL standard includes a PREPARE statement, but it is only for use in embedded SQL. The PostgreSQL version of the PREPARE statement works like this:
PREPARE nameByAge(number) AS
SELECT name
FROM People
WHERE age=$1;
and you use it like this:
EXECUTE nameByAge(18);
EXECUTE nameByAge(50);
So unfortunately for Oracle SQLPlus the answer seems to be no, not bind variables. But SQLPlus has substitution variables, similar to shell scripts. You use them as &1, &2, &3, ... and they get their parameters from the way you call the SQLPlus script.
sqlplus user/password #script.sql 18
sqlplus user/password #script.sql 50
with the script.sql being
SELECT name
FROM People
WHERE age=&1;
this would work, even though it is not bind. But then, do you really care about the slight savings in repeat parse time? In fact Oracle hashes SQL statements and already replaces constants with bind variables to be able to better reuse query plans. So the savings you would get with PREPARE and BIND are really minuscule.
I would like to run some ad hoc select statements in the IBM System I Navigator tool for DB2 using a variable that I declare.
For example, in the SQL Server world I would easily do this in the SQL Server Management Studio query window like so:
DECLARE #VariableName varchar(50);
SET #VariableName = 'blah blah';
select * from TableName where Column = #VariableName;
How can I do something similar in the IBM System I Navigator tool?
I ran across this post while searching for the same question. My coworker provided the answer. It is indeed possible to declare variables in an ad hoc SQL statement in Navigator. This is how it is done:
CREATE OR REPLACE VARIABLE variableName VARCHAR(50);
SET variableName = 'blah';
SELECT * FROM table WHERE column = variableName;
DROP VARIABLE variableName;
If you don't drop the variable name it will hang around until who knows when...
At the moment, we're working on the same issue at work. Unfortunaly, we concluded that this is not possible. I agree, it would be great but it just doesn't work that way. iNavigator doesn't support SET or Define. You can do that in embedded SQL but this is not embedded SQL. Even if you create a separate document (xxx.sql), then need to open this document to run the script what makes it an interactive script (that is, DECLARE SECTION is not allowed).
As an alternative, in the SQL screen/script you can use CL:. Anything after this prefix is executed as CL command. You may manipulate your tables (e.g. RNMF) this way.
As a second alternative, the iSeries does support Rexx scripts (default installed with the os). Rexx is good dynamic script language and it does support embedded SQL. I've done that a lot of times and it works great. I even created scripts for our production environment.
Just create one 'default' script with an example PREPARE and CURSOR statement and copy at will. With that script you can play around. See the Rexx manual for the correct syntax of exec-sql. Also, you do have STDIN and STDOUT but you can use 'OVRDBF' to point to a database table (physical file). Just let me know if you need an example Rexx script.
Notice that the manual "SQL embedded programming" does have Rexx examples.
Here are a couple of other alternatives.
Data Transfer Tool - You can run the iSeries Data Transfer Tool from the command line (RTOPCB). First, run the GUI version and create a definition file. If you edit this file with a text editor, you will see that this is just an old-fashioned INI file and you can easily find the line with the query in it. From there, you could write a batch file or otherwise pre-process the text file to allow you to manipulate the query before submitting it to the query tool.
QSHELL - If you can log on to the iSeries interactively, then you may find the QSHELL environment more familiar than CL or REXX (although REXX is kind of fun). QSHELL is a full POSIX environment running on the iSeries. Use the command STRQSH to start QSHELL. You can have ksh or csh as a shell. Inside QSHELL, there is a command called "db2" that submits queries. So, you should be able to do something like this inside QSHELL:
system> VariableName = 'blah blah'
system> db2 "select * from TableName where Column = \'$VariableName\'"
You may have to fiddle with the quotes to get ksh to pass them correctly.
Also, inside QSHELL, you should have a full Perl installation that will allow you to use DBI to get data.
Some other ways to interact with data on the iSeries: query from the client with Python via ODBC; query from the client with Jython via JDBC; install Jython directly on the iSeries and then query via JDBC.