Returning rows that had no matches - sql

I've read and read and read but I haven't found a solution to my problem.
I'm doing something like:
SELECT a
FROM t1
WHERE t1.b IN (<external list of values>)
There are other conditions of course but this is the jist of it.
My question is: is there a way to show which in the manually entered list of values didn't find a match? I've looked but I can't find and I'm going in circles.

Create a temp table with the external list of values, then you can do:
select item
from tmptable t
where t.item not in ( select b from t1 )
If the list is short enough, you can do something like:
with t as (
select case when t.b1='FIRSTITEM' then 1 else 0 end firstfound
case when t.b1='2NDITEM' then 1 else 0 end secondfound
case when t.b1='3RDITEM' then 1 else 0 end thirdfound
...
from t1 wher t1.b in 'LIST...'
)
select sum(firstfound), sum(secondfound), sum(thirdfound), ...
from t
But with proper rights, I would use Nicholas' answer.

To display which values in the list of values haven't found a match, as one of the approaches, you could create a nested table SQL(schema object) data type:
-- assuming that the values in the list
-- are of number datatype
create type T_NumList as table of number;
and use it as follows:
-- sample of data. generates numbers from 1 to 11
SQL> with t1(col) as(
2 select level
3 from dual
4 connect by level <= 11
5 )
6 select s.column_value as without_match
7 from table(t_NumList(1, 2, 15, 50, 23)) s -- here goes your list of values
8 left join t1 t
9 on (s.column_value = t.col)
10 where t.col is null
11 ;
Result:
WITHOUT_MATCH
-------------
15
50
23
SQLFiddle Demo

There is no easy way to convert "a externally provided" list into a table that can be used to do the comparison. One way is to use one of the (undocumented) system types to generate a table on the fly based on the values supplied:
with value_list (id) as (
select column_value
from table(sys.odcinumberlist (1, 2, 3)) -- this is the list of values
)
select l.id as missing_id
from value_list l
left join t1 on t1.id = l.id
where t1.id is null;

There are ways to get what you have described, but they have requirements which exceed the statement of the problem. From the minimal description provided, there's no way to have the SQL return the list of the manually-entered values that did not match.
For example, if it's possible to insert the manually-entered values into a separate table - let's call it matchtbl, with the column named b - then the following should do the job:
SELECT matchtbl.b
FROM matchtbl
WHERE matchtbl.b NOT IN (SELECT distinct b
FROM t1)
Of course, if the data is being processed by a programming language, it should be relatively easy to keep track of the set of values returned by the original query, by adding the b column to the output, and then perform the set difference.

Putting the list in an in clause makes this hard. If you can put the list in a table, then the following works:
with list as (
select val1 as value from dual union all
select val2 from dual union all
. . .
select valn
)
select list.value, count(t1.b)
from list left outer join
t1
on t1.b = list.value
group by list.value;

Related

SELECT VALUES in Teradata

I know that it's possible in other SQL flavors (T-SQL) to "select" provided data without a table. Like:
SELECT *
FROM (VALUES (1,2), (3,4)) tbl
How can I do this using Teradata?
Teradata has strange syntax for this:
select t.*
from (select * from (select 1 as a, 2 as b) x
union all
select * from (select 3 as a, 4 as b) x
) t;
I don't have access to a TD system to test, but you might be able to remove one of the nested SELECTs from the answer above:
select x.*
from (
select 1 as a, 2 as b
union all
select 3 as a, 4 as b
) x
If you need to generate some random rows, you can always do a SELECT from a system table, like sys_calendar.calendar:
SELECT 1, 2
FROM sys_calendar.calendar
SAMPLE 10;
Updated example:
SELECT TOP 1000 -- Limit to 1000 rows (you can use SAMPLE too)
ROW_NUMBER() OVER() MyNum, -- Sequential numbering
MyNum MOD 7, -- Modulo operator
RANDOM(1,1000), -- Random number between 1,1000
HASHROW(MyNum) -- Rowhash value of given column(s)
FROM sys_calendar.calendar; -- Use as table to source rows
A couple notes:
make sure you pick a system table that will always be present and have rows
if you need more rows than are available in the source table, do a UNION to get more rows
you can always easily create a one-column table and populate it to whatever number of rows you want by INSERT/SELECT into it:
CREATE DummyTable (c1 INT); -- Create table
INSERT INTO DummyTable(1); -- Seed table
INSERT INTO DummyTable SELECT * FROM DummyTable; -- Run this to duplicate rows as many times are you want
Then use this table to create whatever resultset you want, similar to the query above with sys_calendar.calendar.
I don't have a TD system to test so you might get syntax errors...but that should give you a basic idea.
I am a bit late to this thread, but recently got the same error.
I solved this by simply using
select distinct 1 as a, 2 as b from DBC.tables
union all
select distinct 3 as a, 4 as b from DBC.tables
Here, DBC.tables is a DB backend table with a few rows only. So, the query runs fast as well

How to join a subquery to itself?

How do can you join a subquery onto itself? I'd like to do something like the following.
SELECT
four.src AS start, four.dest AS layover, f.dest AS destination
FROM
( SELECT 1 AS src, 2 as dest union all select 2, 3 ) AS four
JOIN
four AS f
ON f.src = four.dest
However the query above gives me the error
Msg 208, Level 16, State 1, Line 1
Invalid object name 'four'.
I'd rather not have to store it as a variable or view etc first since this is part of a monolithic query (this is itself a subquery and its part of a series of UNIONS) and I do not want to make sure that there are no impacting joins elsewhere that relate.
The force behind this change is that fourused to be a simple lookup but now for this query the values have to be calculated.
PS - this is a simplified example, in my case the subquery for four is a hundred lines long
You can make use of CTE (Common Table Expression in this scenario. Here, you need not to store this result in any temporary objects.
;WITH four AS (
SELECT 1 AS src, 2 as dest
union all
select 2, 3
)
SELECT F1.src AS start, F1.dest AS layover, f2.dest AS destination
FROM four F1
INNER JOIN four F2 ON F1.src = F2.dest
Use a temp table.
Declare #Temp(src int, desc int);
INSERT INTO #Temp(src,desc)
VALUES
(SELECT 1 AS src, 2 as dest union all select 2, 3)
SELECT * FROM #Temp t1
INNER JOIN #Temp t2 ON t1.src = t2.dest
You need to write it again. You alias 'four' can only be called in 'Select','Where', 'have', 'On'etc. conditions only and NOT as table in joins until and unless it's a table name in itself
SELECT
four.src AS start, four.dest AS layover, f.dest AS destination
FROM
(SELECT 1 AS src, 2 as dest union all select 2, 3 ) AS four
JOIN
(SELECT 1 AS src, 2 as dest union all select 2, 3 ) AS f
ON f.src = four.dest

Oracle SQL - How can I write an insert statement that is conditional and looped?

Context:
I have two tables: markettypewagerlimitgroups (mtwlg) and stakedistributionindicators (sdi). When a mtwlg is created, 2 rows are created in the sdi table which are linked to the mtwlg - each row with the same values bar 2, the id and another field (let's call it column X) which must contain a 0 for one row and 1 for the other.
There was a bug present in our codebase which prevented this happening automatically, so any mtwlg's created during the time that bug was present do not have the related sdi's, causing NPE's in various places.
To fix this, a patch needs to be written to loop through the mtwlg table and for each ID, search the sdi table for the 2 related rows. If the rows are present, do nothing; if there is only 1 row, check if F is a 0 or a 1, and insert a row with the other value; if neither row is present, insert them both. This needs to be done for every mtwlg, and a unique ID needs to be inserted too.
Pseudocode:
For each market type wager limit group ID
Check if there are 2 rows with that id in the stake distributions table, 1 where column X = 0 and one where column X = 1
if none
create 2 rows in the stake distributions table with unique id's; 1 for each X value
if one
create the missing row in the stake distributions table with a unique id
if 2
do nothing
If it helps at all - the patch will be applied using liquibase.
Anyone with any advice or thoughts as to if and how this will be possible to write in SQL/a liquibase patch?
Thanks in advance, let me know of any other information you need.
EDIT:
I've actually just been advised to do this using PL/SQL, do you have any thoughts/suggestions in regards to this?
Thanks again.
Oooooh, an excellent job for MERGE.
Here's your pseudo code again:
For each market type wager limit group ID
Check if there are 2 rows with that id in the stake distributions table,
1 where column X = 0 and one where column X = 1
if none
create 2 rows in the stake distributions table with unique id's;
1 for each X value
if one
create the missing row in the stake distributions table with a unique id
if 2
do nothing
Here's the MERGE variant (still pseudo-code'ish as I don't know how your data really looks):
MERGE INTO stake_distributions d
USING (
SELECT limit_group_id, 0 AS x
FROM market_type_wagers
UNION ALL
SELECT limit_group_id, 1 AS x
FROM market_type_wagers
) t
ON (
d.limit_group_id = t.limit_group_id AND d.x = t.x
)
WHEN NOT MATCHED THEN INSERT (d.limit_group_id, d.x)
VALUES (t.limit_group_id, t.x);
No loops, no PL/SQL, no conditional statements, just plain beautiful SQL.
Nice alternative suggested by Boneist in the comments uses a CROSS JOIN rather than UNION ALL in the USING clause, which is likely to perform better (unverified):
MERGE INTO stake_distributions d
USING (
SELECT w.limit_group_id, x.x
FROM market_type_wagers w
CROSS JOIN (
SELECT 0 AS x FROM DUAL
UNION ALL
SELECT 1 AS x FROM DUAL
) x
) t
ON (
d.limit_group_id = t.limit_group_id AND d.x = t.x
)
WHEN NOT MATCHED THEN INSERT (d.limit_group_id, d.x)
VALUES (t.limit_group_id, t.x);
Answer: you don't. There is absolutely no need to loop through anything - you can do it in a single insert. All you need to do is identify the rows that are missing, and then you just need to add them in.
Here is an example:
drop table t1;
drop table t2;
drop sequence t2_seq;
create table t1 (cola number,
colb number,
colc number);
create table t2 (id number,
cola number,
colb number,
colc number,
colx number);
create sequence t2_seq
START WITH 1
INCREMENT BY 1
MAXVALUE 99999999
MINVALUE 1
NOCYCLE
CACHE 20
NOORDER;
insert into t1 values (1, 10, 100);
insert into t2 values (t2_seq.nextval, 1, 10, 100, 0);
insert into t2 values (t2_seq.nextval, 1, 10, 100, 1);
insert into t1 values (2, 20, 200);
insert into t2 values (t2_seq.nextval, 2, 20, 200, 0);
insert into t1 values (3, 30, 300);
insert into t2 values (t2_seq.nextval, 3, 30, 300, 1);
insert into t1 values (4, 40, 400);
commit;
insert into t2 (id, cola, colb, colc, colx)
with dummy as (select 1 id from dual union all
select 0 id from dual)
select t2_seq.nextval,
t1.cola,
t1.colb,
t1.colc,
d.id
from t1
cross join dummy d
left outer join t2 on (t2.cola = t1.cola and d.id = t2.colx)
where t2.id is null;
commit;
select * from t2
order by t2.cola;
ID COLA COLB COLC COLX
---------- ---------- ---------- ---------- ----------
1 1 10 100 0
2 1 10 100 1
3 2 20 200 0
5 2 20 200 1
7 3 30 300 0
4 3 30 300 1
6 4 40 400 0
8 4 40 400 1
If the processing logic is too gnarly to be encapsulated in a single SQL statement, you may need to resort to cursor for loops and row types - basically allows you to do things like the following:
DECLARE
r_mtwlg markettypewagerlimitgroups%ROWTYPE;
BEGIN
FOR r_mtwlg IN (
SELECT mtwlg.*
FROM markettypewagerlimitgroups mtwlg
)
LOOP
-- do stuff here
-- refer to elements of the current row like this
DBMS_OUTPUT.PUT_LINE(r_mtwlg.id);
END LOOP;
END;
/
You can obviously nest another loop inside this one that hits the stakedistributionindicators table, but I'll leave that as an exercise for you. You could also left join to stakedistributionindicators a couple of times in this first cursor so that you only return rows that don't already have an x=1 and x=0, again you can probably work that bit out for yourself.
If you would rather write your logic in Java vs. PL/SQL, Liquibase allows you to create custom changes. The custom change points to a Java class you write that can do whatever logic you need. A simple example can be found here

create a table of duplicated rows of another table using the select statement

I have a table with one column containing different integers.
For each integer in the table I would like to duplicate it as the number of digits -
For example:
12345 (5 digits):
1. 12345
2. 12345
3. 12345
4. 12345
5. 12345
I thought doing it using with recursion t (...) as () but I didn't manage, since I don't really understand how it works and what is happening "behind the scenes.
I don't want to use insert because I want it to be scalable and automatic for as many integers as needed in a table.
Any thoughts and an explanation would be great.
The easiest way is to join to a table with numbers from 1 to n in it.
SELECT n, x
FROM yourtable
JOIN
(
SELECT day_of_calendar AS n
FROM sys_calendar.CALENDAR
WHERE n BETWEEN 1 AND 12 -- maximum number of digits
) AS dt
ON n <= CHAR_LENGTH(TRIM(ABS(x)))
In my example I abused TD's builtin calendar, but that's not a good choice, as the optimizer doesn't know how many rows will be returned and as the plan must be a Product Join it might decide to do something stupid. So better use a number table...
Create a numbers table that will contain the integers from 1 to the maximum number of digits that the numbers in your table will have (I went with 6):
create table numbers(num int)
insert numbers
select 1 union select 2 union select 3 union select 4 union select 5 union select 6
You already have your table (but here's what I was using to test):
create table your_table(num int)
insert your_table
select 12345 union select 678
Here's the query to get your results:
select ROW_NUMBER() over(partition by b.num order by b.num) row_num, b.num, LEN(cast(b.num as char)) num_digits
into #temp
from your_table b
cross join numbers n
select t.num
from #temp t
where t.row_num <= t.num_digits
I found a nice way to perform this action. Here goes:
with recursive t (num,num_as_char,char_n)
as
(
select num
,cast (num as varchar (100)) as num_as_char
,substr (num_as_char,1,1)
from numbers
union all
select num
,substr (t.num_as_char,2) as num_as_char2
,substr (num_as_char2,1,1)
from t
where char_length (num_as_char2) > 0
)
select *
from t
order by num,char_length (num_as_char) desc

Count(*) with 0 for boolean field

Let's say I have a boolean field in a database table and I want to get a tally of how many are 1 and how many are 0. Currently I am doing:
SELECT 'yes' AS result, COUNT( * ) AS num
FROM `table`
WHERE field = 1
UNION
SELECT 'no' AS result, COUNT( * ) AS num
FROM `table`
WHERE field = 0;
Is there an easier way to get the result so that even if there are no false values I will still get:
----------
|yes | 3 |
|no | 0 |
----------
One way would be to outer join onto a lookup table. So, create a lookup table that maps field values to names:
create table field_lookup (
field int,
description varchar(3)
)
and populate it
insert into field_lookup values (0, 'no')
insert into field_lookup values (1, 'yes')
now the next bit depends on your SQL vendor, the following has some Sybase (or SQL Server) specific bits (the outer join syntax and isnull to convert nulls to zero):
select description, isnull(num,0)
from (select field, count(*) num from `table` group by field) d, field_lookup fl
where d.field =* fl.field
you are on the right track, but the first answer will not be correct. Here is a solution that will give you Yes and No even if there is no "No" in the table:
SELECT 'Yes', (SELECT COUNT(*) FROM Tablename WHERE Field <> 0)
UNION ALL
SELECT 'No', (SELECT COUNT(*) FROM tablename WHERE Field = 0)
Be aware that I've checked Yes as <> 0 because some front end systems that uses SQL Server as backend server, uses -1 and 1 as yes.
Regards
Arild
This will result in two columns:
SELECT SUM(field) AS yes, COUNT(*) - SUM(field) AS no FROM table
Because there aren't any existing values for false, if you want to see a summary value for it - you need to LEFT JOIN to a table or derived table/inline view that does. Assuming there's no TYPE_CODES table to lookup the values, use:
SELECT x.desc_value AS result,
COALESCE(COUNT(t.field), 0) AS num
FROM (SELECT 1 AS value, 'yes' AS desc_value
UNION ALL
SELECT 2, 'no') x
LEFT JOIN TABLE t ON t.field = x.value
GROUP BY x.desc_value
SELECT COUNT(*) count, field FROM table GROUP BY field;
Not exactly same output format, but it's the same data you get back.
If one of them has none, you won't get that rows back, but that should be easy enough to check for in your code.