Oracle 12cR1 - I have a complex business process I am putting into a query.
In general, the process will be
with t1 as (select CATEGORY, PRODUCT from ... )
select <some manipulation> from t1;
t1 -aka the output of the first line- will look like this:
CATEGORY PRODUCT
Database Oracle, MS SQL Server, DB2
Language C, Java, Python
I need the 2nd line of the SQL query (aka the manipulation) to keep the CATEGORY column, and to split the PRODUCT column on the comma. The output needs to look like this
CATEGORY PRODUCT
Database Oracle
Database MS SQL Server
Database DB2
Language C
Language Java
Language Python
I have looked at a couple of different CSV splitting options. I cannot use the DBMS_Utility.comma_to_Table function as this has restrictions with special characters or starting with numbers. I found a nice TABLE function which will convert a string to separate rows, called f_convert. This function is on StackOverflow about 1/3 the way down the page here.
Since this is a table function, it is called like so...And will give me 3 rows, as expected.
SELECT * FROM TABLE(f_convert('Oracle, MS SQL Server, DB2'));
How do I treat this TABLE function as it is was a "column function"? Although this is totally improper SQL, I am looking for something like
with t1 as (select CATEGORY, PRODUCT from ... )
select CATEGORY from T1, TABLE(f_convert(PRODUCT) as PRODUCT from t1;
Any help appreciated...
Use connect by to "loop" through the elements of the list where a comma-space is the delimiter. regexp_substr gets the list elements (the regex allows for NULL list elements) and the prior clauses keep the categories straight.
with t1(category, product) as (
select 'Database', 'Oracle, MS SQL Server, DB2' from dual union all
select 'Language', 'C, Java, Python' from dual
)
select category,
regexp_substr(product, '(.*?)(, |$)', 1, level, NULL, 1) product
from t1
connect by level <= regexp_count(product, ', ')+1
and prior category = category
and prior sys_guid() is not null;
CATEGORY PRODUCT
-------- --------------------------
Database Oracle
Database MS SQL Server
Database DB2
Language C
Language Java
Language Python
6 rows selected.
SQL>
Related
In SQL Developer, we can use parameters in order to test our query with different values - for example:
I have a table called Fruits (code, name). I want to retrieve code's apples.
SELECT *
FROM fruits
WHERE name IN (:PM_NAME)
It works correctly when I fill out one value (in this case :PM_NAME equal apple)
But when I want to fill out many values it doesn't work! I've tried these forms and these separators but still..
apple;orange
'apple';'orange'
('apple','orange')
['apple','orange']
"apple","orange"
In a nutshell what's the correct format to fill out multiple values in a SQL parameter in SQL Developer ?
I can't take credit for this 'trick' but the solution lies in a regular expression.
I want to search on multiple types of objects, fed to a :bind, and used in a WHERE clause.
SELECT owner,
object_name,
object_type
FROM all_objects
WHERE object_name LIKE :SEARCH
AND owner NOT IN (
'SYS',
'MDSYS',
'DBSNMP',
'SYSTEM',
'DVSYS',
'APEX_050100',
'PUBLIC',
'ORDS_METADATA',
'APEX_LISTENER'
)
AND object_type IN (
SELECT regexp_substr(:bind_ename_comma_sep_list,'[^,]+',1,level)
FROM dual CONNECT BY
regexp_substr(:bind_ename_comma_sep_list,'[^,]+',1,level) IS NOT NULL
)
ORDER BY owner,
object_name,
object_type;
I first learned of this 'trick' or technique from here.
So your query would look like this
SELECT *
FROM fruits
WHERE name IN (
SELECT regexp_substr(:PM_NAME,'[^,]+',1,level)
FROM dual CONNECT BY
regexp_substr(:PM_NAME,'[^,]+',1,level) IS NOT NULL
)
When you're prompted for values by SQL Developer, don't quote the strings, just comma separate them. Also, no spaces.
So in the input box, enter
apple,orange
And I suppose if you want ; vs , then update the regex call as needed.
Postgres 9.1 - I have a schema that has tables "partitioned" by month (a new table is created each month, all columns the same). It is not set up as normal partitioning with a "master" table. I am currently writing a fairly large query, that I will have to run a few times each month.
Schema: augmented_events
tables:
p201301 (January 2013)
p201302 (Feb 2013)
p201303 (March 2013)
...
p201312 (December 2013)
p201401 (January 2014)
Right now I have to write my (simplified) query as:
select *
from augmented_events.p201301
union
select *
from augmented_events.p201302
union
select *
from augmented_events.p201303
union
select *
from augmented_events.p201312
union
select *
from augmented_events.p201401
And every month I need to add in the new month. I would like to make this a little more scalable without me having to revisit it every month. Is there a function I can create (or one that exists) that loops through each table in the augmented_events schema, and treats it as if I was to union these tables?
Proper solution
... would be partitioning via inheritance. It's rather simple actually. Consider this related answer:
Select (retrieve) all records from multiple schemas using Postgres
For now
While stuck with your unfortunate design, you can use dynamic SQL in a plpgsql function with EXECUTE.
Create this function once:
CREATE OR REPLACE FUNCTION f_all_in_schema_foo()
RETURNS SETOF t
LANGUAGE plpgsql AS
$func$
BEGIN
RETURN QUERY EXECUTE (
SELECT string_agg(format('SELECT * FROM %s', c.oid ::regclass)
,E'\nUNION ALL\n'
ORDER BY relname)
FROM pg_namespace n
JOIN pg_class c ON c.relnamespace = n.oid
WHERE n.nspname = 'foo'
AND c.relkind = 'r'
);
END
$func$;
Note how I carefully avoid any possibility for SQL injection (table names have to be considered as "user input"!). See:
Table name as a PostgreSQL function parameter
Generates and executes a query of the form:
SELECT * FROM foo.p201301
UNION ALL
SELECT * FROM foo.p201302
UNION ALL
SELECT * FROM foo.p201303
UNION ALL
...
Tables are ordered by name due to the ORDER BY clause in string_agg().
You can use this table function just like a table. Call:
SELECT * FROM f_all_in_schema_foo();
Performance should be good.
You can find similar examples with explanation and links here on SO with this search.
I doubt there's anything like this possible in straight SQL, but you could use outside code (PHP, Perl, .NET; whatever's familiar to you). It would query the schema, drop the old view, and create the new. Schedule it to run daily and you'll be able to use the view without giving a thought to which tables are included.
This is a Band-Aid: better would be to correct this pseudo-partitioning.
I'm working with an oracle DB and need to manipulate a string column within it. The column contains multiple email addresses in this format:
jgooooll#gmail.com;dhookep#gmail.com;amoore#outlook.com
What I want to do is take out anything that does not have '#gmail.com' at the end (in this example amoore#outlook.com would be removed) however amoore#outlook.com may be the first email in the next row of the column so in this way there is no real fixed format, the only format being that each address is seperated by a semi-colon.
Is there anyway of implementing this through one command to run through every row in the column and remove anything thats not #gmail.com? I'm not really sure if this kind of processing is possible in SQL. Just looking for your thoughts!!
Thanks a lot you guys. Look forward to hearing from you!
Applicable to Oracle 11g (11.2) onward only. Because listagg function is supported only in 11.2 onward. If you are using 10.1 onward up to 11.1, you can write your own string aggregate function or take this one.
with T1 as (
select 1 id, 'jhd#jk.com;jgooooll#gmail.com;dhookep#gmail.com;amoore#outlook.com' emails from dual union all
select 2 id, 'jhd#jk.com;jgooooll#gmail.com;dhookep#gmail.com;amoore#outlook.com' emails from dual
)
select id
, listagg(email, ';') within group(order by id) emails
from (select id
, regexp_substr(emails,'[^;]+', 1, rn) email
from t1
cross join (select rownum rn
from(select max (regexp_count(emails, '[^;]+')) ml
from t1
)
connect by level <= ml
)
)
where email like '%#gmail.com%'
group by id
Id Emails
--------------------------------------
1 dhookep#gmail.com;jgooooll#gmail.com
2 dhookep#gmail.com;jgooooll#gmail.com
Here is a Demo
This answer is actually for SQL Server, as that is what I know. That being said, perhaps having an example of how to do it in one system will give you an idea of how to do it in yours. Or maybe there is a way to convert the code into the same type of thing in Oracle.
First, the thought process: In SQL Server combining the FOR XML PATH and STUFF functionality allows you to make a comma separated list. I'm adding a WHERE Split.SplitValue LIKE ... clause into this to filter it to only gmail addresses. I'm cross applying this whole thing to the main table, and that turns it into a filtered email list. You could then further filter the main table to run this on a more targeted set of rows.
Second, the SQL Server implementation:
SELECT
*
FROM #Table Base
CROSS APPLY
(
SELECT
STUFF(
(SELECT
';' + Split.SplitValue AS [text()]
FROM dbo.fUtility_Split(Base.Emails, ';') Split
WHERE Split.SplitValue LIKE '%#gmail.com'
FOR XML PATH (''))
, 1, 1, '') Emails
) FilteredEmails
EDIT: I forgot to mention that this answer requires you have some sort of function to split a string column based on a separator value. If you don't have that already, then google for it. There are tons of examples.
How do I create a temporary result set for use in an SQL without creating a table and inserting the data?
Example: I have a list of, say 10 codes for example. I want to put this into a query, and then query the database to see which codes in this temporary list do not exist in a table.
If it was already in a table, I could do something like:
SELECT
ITEM_CODE
FROM
TEMP_ITEMS
MINUS
SELECT
ITEM_CODE
FROM
M_ITEMS
Is their a way without using PL/SQL, and pure SQL to create a temporary rowset before querying?
Please don't answer with something like:
SELECT 1 FROM DUAL
UNION ALL
SELECT 2 FROM DUAL
I am sort of thinking of something where I can provide my codes in an IN statement, and it turns that into rows for use in a later query.
Edit: so everyone knows my objective here, basically I sometimes get a list of product codes that I need to find which ones in the list are not setup in our system. I want a quick way to throw this into an SQL statement so I can see which ones are not in the system (rather than importing data etc). I usually put these into excel, then do a formula such as :
="'"&A1&"',"
So that I can create my comma separated list.
If you are using oracle 11g you can do this
with t as
(
select (column_value).getnumberval() Codes from xmltable('1,2,3,4,5')
)
SELECT * FROM t
WHERE NOT EXISTS (SELECT 1 FROM M_ITEMS M WHERE codes = M.ITEM_CODE);
or
with t as
(
select (column_value).getstringval() Codes from xmltable('"A","B","C"')
)
SELECT * FROM t
WHERE NOT EXISTS (SELECT 1 FROM M_ITEMS M WHERE codes = M.ITEM_CODE);
I would go with:
with t as (
select 1 as val from dual union all
select 2 as val from dual
)
select . . .
And then use "t" or whatever you call it, in the subsequent query block.
I'm not sure what the objection is to using the select method . . . just pop the values you want in a column in Excel and produce the code for each value by copying down the formula. Then paste the results back into your query interface.
If you want to use a temporary table, you can use the values clause. Alternatively, you can use string functions if you only want IN functionality. Put the values in a comma separated list and check to see if it matches a particular value:
where ','||<list>||',' like '%,'||col||',%'
This one is interesting because it's not a union and fit in a single select. You have to enter the string with delimiters ('a/b/c/def') two times though:
SELECT regexp_substr('a/b/c/def', '[^/]+', 1, ROWNUM) var,
regexp_substr('2/432/sd/fsd', '[^/]+', 1, ROWNUM) var2
FROM dual
CONNECT BY LEVEL <= length(regexp_replace('a/b/c/def', '[^/]', '')) + 1;
var var2
=== ====
a 2
b 432
c sd
def fsd
Note: Credits go to : https://stackoverflow.com/a/1381495/463056
So using the with clause it would give someting like :
with tempo as (
SELECT regexp_substr('a/b/c/def', '[^/]+', 1, ROWNUM) var,
regexp_substr('2/432/sd/fsd', '[^/]+', 1, ROWNUM) var2
FROM dual
CONNECT BY LEVEL <= length(regexp_replace('a/b/c/def', '[^/]', '')) + 1
)
select ...
or you can use it in a from clause :
select ...
from (
SELECT regexp_substr('a/b/c/def', '[^/]+', 1, ROWNUM) var,
regexp_substr('2/432/sd/fsd', '[^/]+', 1, ROWNUM) var2
FROM dual
CONNECT BY LEVEL <= length(regexp_replace('a/b/c/def', '[^/]', '')) + 1
) tempo
There are two approaches I would lean towards:
1. Global Temporary Table
Although you say you don't want to create a table, it depends on why you don't want a table. If you choose to create a Global Temporary table, the rows are only visible to the session that inserted them, so it's like having a private in-memory table but gives you all the benefits of a real table - i.e. being able to query and join to it.
2. Pipelined function
You can create a function that returns the results in a form that can be queried using the TABLE() operator. More info here: http://www.oracle-base.com/articles/misc/pipelined-table-functions.php
It's a bit hokey-looking. But you can parse a string into separate rows using regular expressions assuming you are using 10g or later. For example
SQL> ed
Wrote file afiedt.buf
1 SELECT REGEXP_SUBSTR('a,b,c,def,g', '[^ |,]+', 1, LEVEL) parsed_str
2 FROM dual
3* CONNECT BY LEVEL <= REGEXP_COUNT('a,b,c,def,g', '[^ |,]+')
SQL> /
PARSED_STR
--------------------------------------------
a
b
c
def
g
Personally, I would find a pipelined table function or a PL/SQL block that generates a collection easier to understand, but if you have to do it in SQL you can.
Based on your edit, if you are getting a list of product codes that is already in some sort of file, it would seem to make more sense to use an external table to expose the file as a table or to use SQL*Loader to load the data into a table (temporary or permanent) that you can query. Barring either of those options, if you really want to manipulate the list in Excel first, it would make more sense to generate an IN list in Excel and just copy and past that into your query. Generating a comma-separated list of codes in Excel only to parse that list into it's constituent elements in SQL seems like way too many steps.
Is it possible to have a statement like
SELECT "Hello world"
WHERE 1 = 1
in SQL?
The main thing I want to know, is can I SELECT from nothing, ie not have a FROM clause.
It's not consistent across vendors - Oracle, MySQL, and DB2 support dual:
SELECT 'Hello world'
FROM DUAL
...while SQL Server, PostgreSQL, and SQLite don't require the FROM DUAL:
SELECT 'Hello world'
MySQL does support both ways.
Try this.
Single:
SELECT * FROM (VALUES ('Hello world')) t1 (col1) WHERE 1 = 1
Multi:
SELECT * FROM (VALUES ('Hello world'),('Hello world'),('Hello world')) t1 (col1) WHERE 1 = 1
more detail here : http://modern-sql.com/use-case/select-without-from
In Oracle:
SELECT 'Hello world' FROM dual
Dual equivalent in SQL Server:
SELECT 'Hello world'
Here is the most complete list of database support of dual from https://blog.jooq.org/tag/dual-table/:
In many other RDBMS, there is no need for dummy tables, as you can
issue statements like these:
SELECT 1;
SELECT 1 + 1;
SELECT SQRT(2);
These are the RDBMS, where the above is generally possible:
H2
MySQL
Ingres
Postgres
SQLite
SQL Server
Sybase ASE
In other RDBMS, dummy tables are required, like in Oracle. Hence,
you’ll need to write things like these:
SELECT 1 FROM DUAL;
SELECT 1 + 1 FROM DUAL;
SELECT SQRT(2) FROM DUAL;
These are the RDBMS and their respective dummy tables:
DB2: SYSIBM.DUAL
Derby: SYSIBM.SYSDUMMY1
H2: Optionally supports DUAL
HSQLDB: INFORMATION_SCHEMA.SYSTEM_USERS
MySQL: Optionally supports DUAL
Oracle: DUAL
Sybase SQL Anywhere: SYS.DUMMY
Ingres has no DUAL, but would actually need it as in Ingres you cannot
have a WHERE, GROUP BY or HAVING clause without a FROM clause.
In SQL Server type:
Select 'Your Text'
There is no need for the FROM or WHERE clause.
You can. I'm using the following lines in a StackExchange Data Explorer query:
SELECT
(SELECT COUNT(*) FROM VotesOnPosts WHERE VoteTypeName = 'UpMod' AND UserId = #UserID AND PostTypeId = 2) AS TotalUpVotes,
(SELECT COUNT(*) FROM Answers WHERE UserId = #UserID) AS TotalAnswers
The Data Exchange uses Transact-SQL (the SQL Server proprietary extensions to SQL).
You can try it yourself by running a query like:
SELECT 'Hello world'
There is another possibility - standalone VALUES():
VALUES ('Hello World');
Output:
column1
Hello World
It is useful when you need to specify multiple values in compact way:
VALUES (1, 'a'), (2, 'b'), (3, 'c');
Output:
column1 column2
1 a
2 b
3 c
DBFiddle Demo
This syntax is supported by SQLite/PostgreSQL/DB LUW/MariaDB 10.3.
In Firebird, you can do this:
select "Hello world" from RDB$DATABASE;
RDB$DATABASE is a special table that always has one row.
I think it is not possible. Theoretically: select performs two sorts of things:
narrow/broaden the set (set-theory);
mapping the result.
The first one can be seen as a horizontal diminishing opposed to the where-clause which can be seen as a vertical diminishing. On the other hand, a join can augment the set horizontally where a union can augment the set vertically.
augmentation diminishing
horizontal join/select select
vertical union where/inner-join
The second one is a mapping. A mapping, is more a converter. In SQL it takes some fields and returns zero or more fields. In the select, you can use some aggregate functions like, sum, avg etc. Or take all the columnvalues an convert them to string. In C# linq, we say that a select accepts an object of type T and returns an object of type U.
I think the confusion comes by the fact that you can do: select 'howdy' from <table_name>. This feature is the mapping, the converter part of the select. You are not printing something, but converting! In your example:
SELECT "
WHERE 1 = 1
you are converting nothing/null into "Hello world" and you narrow the set of nothing / no table into one row, which, imho make no sense at all.
You may notice that, if you don't constrain the number of columns, "Hello world" is printed for each available row in the table. I hope, you understand why by now. Your select takes nothing from the available columns and creates one column with the text: "Hello world".
So, my answer is NO. You can't just leave out the from-clause because the select always needs table-columns to perform on.
In Standard SQL, no. A WHERE clause implies a table expression.
From the SQL-92 spec:
7.6 "where clause"
Function
Specify a table derived by the
application of a "search condition" to
the result of the preceding "from
clause".
In turn:
7.4 "from clause"
Function
Specify a table derived from one or more named tables.
A Standard way of doing it (i.e. should work on any SQL product):
SELECT DISTINCT 'Hello world' AS new_value
FROM AnyTableWithOneOrMoreRows
WHERE 1 = 1;
...assuming you want to change the WHERE clause to something more meaningful, otherwise it can be omitted.
For ClickHouse, the nothing is system.one
SELECT 1 FROM system.one
I know this is an old question but the best workaround for your question is using a dummy subquery:
SELECT 'Hello World'
FROM (SELECT name='Nothing') n
WHERE 1=1
This way you can have WHERE and any clause (like Joins or Apply, etc.) after the select statement since the dummy subquery forces the use of the FROM clause without changing the result.
For DB2:
`VALUES('Hello world')`
You can do multiple "rows" as well:
`VALUES('Hello world'),('Goodbye world');`
You can even use them in joins as long as the types match:
VALUES(1,'Hello world')
UNION ALL
VALUES(2,'Goodbye world');
I'm using firebird
First of all, create a one column table named "NoTable" like this
CREATE TABLE NOTABLE
(
NOCOLUMN INTEGER
);
INSERT INTO NOTABLE VALUES (0); -- You can put any value
now you can write this
select 'hello world' as name
from notable
you can add any column you want to be shown