Lets say I have a table with 2 columns (a, b) with following values:
a b
--- ---
1 5
1 NULL
2 NULL
2 NULL
3 NULL
My desired output:
a
---
2
3
I want to select only those distinct values from column a for which every single occurrence of this value has NULL in column b. Therefore from my desired output, "1" won't come in because there is a "5" in column b even though there is a NULL for the 2nd occurrence of "1".
How can I do this using a TSQL query?
If I understand correctly, you can do this with group by and having:
select a
from t
group by a
having count(b) = 0;
When you use count() with a column name, it counts the number of non-NULL values. Hence, if all values are NULL, then the value will be zero.
It's fairly simple to do:
SELECT A
FROM table1
GROUP BY A
HAVING COUNT(B) = 0
Grouping by A results in all the rows where the value of A is identical to be transferred into a single row in the output. Adding the HAVING clause enables to filter those grouped rows with an aggregate function. COUNT doesn't count NULL values, so when it's 0, there are no other values in B.
Two more ways to do this:
SELECT a
FROM t
EXCEPT
SELECT a
FROM t
WHERE b IS NOT NULL ;
This would use an index on (a, b):
SELECT a
FROM t
GROUP BY a
WHERE MIN(b) IS NOT NULL ;
Try it like this:
DECLARE #tbl TABLE(a INT, b INT);
INSERT INTO #tbl VALUES(1,5),(1,NULL),(2,NULL),(2,NULL),(3,NULL);
--Your test data
SELECT * FROM #tbl;
--And this is what you want - hopefully...
SELECT DISTINCT tbl.a
FROM #tbl AS tbl
WHERE NOT EXISTS(SELECT * FROM #tbl AS x WHERE x.a=tbl.a AND b IS NOT NULL)
To turn your question on it's head, you want the values from column a where there are no non-null values for that value in column b.
select distinct a
from table1 as t1
where 0 = (select count(*)
from table1 as t2
where t1.a = t2.a
and b is not null)
Sample fiddle is here: http://sqlfiddle.com/#!6/5d1b8/1
This should do it:
SELECT DISTINCT a
FROM t
WHERE b IS NULL
AND a NOT IN (SELECT a FROM t WHERE b IS NOT NULL);
Related
I am selecting the records from 2 tables in which the 1st table column named DESC (first 3 characters) should match with the project column of the 2nd table.
I want to get the last 2 characters from Table 1 column DESC to be added in my output, but the last 2 characters are not present in Table 2 column project.
select SUBSTRING(a.[DESC], 1, 3)
from Table1 a
join Table2 b on SUBSTRING(a.[DESC], 1, 3) = b.project
Input: 1st Table DESC Column: Value: '2AB F YY'
2nd Table Project Column: Value: '2AB'
Expected Output: Return all the records of value 2AB
Column result:
'2AB YY'
Wrong output: all the records of value starting other then 2AB
One option is as follows
with data
as (
select SUBSTRING(a.[DESC],1,3) as first_3_characters,
,REVERSE(SUBSTRING(REVERSE(a.[DESC]),1,2)) as last_2_char_tab1
,REVERSE(SUBSTRING(REVERSE(b.project),1,2)) as last_2_char_tab2 characters_tab2
from Table1 a
join Table2 b
on SUBSTRING(a.[DESC],1,3) = b.project
)
select *,CONCAT(first_3_characters,last_2_characters)
from data
where last_2_char_tab1 <> last_2_char_tab2
Since you don't seem to need data from Table2, an EXISTS could be used for this.
And RIGHT can be used to get the last N characters of a string.
SELECT
CONCAT(LEFT([DESC], 3),' ', RIGHT([DESC], 2))
FROM Table1 t1
WHERE EXISTS
(
SELECT 1
FROM Table2 t2
WHERE t2.project = LEFT(t1.[DESC], 3)
)
ORDER BY 1;
I have a table with following format and I want to get the LotId if Value1 is null for all the rows.
Now If I am doing Select,
Select * from Table1 where Value1 IS null , I am getting back a row .
But I want nothing should be returned as there are two rows which have some value.
I thought of self join , but this can have n number of rows.
Id LotId Value1
-------------------------------------------------
1 LOt0065 NULL
2 LOt0065 SomeValue
3 LOt0065 SomeValue
I think you'll need to use an EXISTS subquery here:
SELECT a.lotid
FROM table1 a
WHERE NOT EXISTS (
SELECT 1
FROM table1 b
WHERE b.lotid = a.lotid
AND b.value1 IS NOT NULL
);
If my syntax is right, then this will show you all records that don't have any NULL values for that lotid:
It uses a SELECT 1 because the subquery doesn't need to show any value, it just needs to match on the outer query.
You compare the table in the inner query to the table in the outer query and match on the common field you're looking at (lotid in this case)
This could also be done with a NOT IN clause.
Does this give you the result you want?
I have 2 tables (A, B). They each have a different column that is basically an order or a sequence number. Table A has 'Sequence' and the values range from 0 to 5. Table B has 'Index' and the values are 16740, 16744, 16759, 16828, 16838, and 16990. Unfortunately I do not know the significance of these values. But I do believe they will always match in sequential order. I want to join these tables on these numbers where 0 = 16740, 1 = 16744, etc. Any ideas?
Thanks
You could use a case expression to convert table a's values to table b's values (or vise-versa) and join on that:
SELECT *
FROM a
JOIN b ON a.[sequence] = CASE b.[index] WHEN 16740 THEN 0
WHEN 16744 THEN 1
WHEN 16759 THEN 2
WHEN 16828 THEN 3
WHEN 16838 THEN 4
WHEN 16990 THEN 5
ELSE NULL
END;
#Mureinik has a great example. If down the road you do end up adding more numbers maybe putting this information into a new table would be a good idea.
CREATE TABLE C(
AInfo INT,
BInfo INT
)
INSERT INTO TABLE C(AInfo,BInfo) VALUES(0,16740)
INSERT INTO TABLE C(AInfo,BInfo) VALUES(1,16744)
etc
Then you can Join all the tables.
If the values are in ascending order as per your example, you can use the ROW_NUMBER() function to achieve this:
;with cte AS (SELECT *, ROW_NUMBER() OVER(ORDER BY [Index])-1 RN
FROM B)
SELECT *
FROM cte
I want to insert multiple rows from one column by splitting column value. But I have to do that without cursors because of performance issues.
Every value is splitted to 6 chars length values. Then these values also splitted to 3, 1 and 2 chars length values to insert different columns in table B.
I think giving a sample will clarify my question:
Table A
ID Value
1 ABCDEFGHJKLM
2 NOPRST
3 NULL VALUE
I want to insert these values into table B like this format
Table B
ID Value1 Value2 Value3
1 ABC D EF
1 GHJ K LM
2 NOP R ST
Supposing 600(100 rows) as maximum length of value:
insert into tableB
select id, substr(value,n*6+1,3), substr(value,n*6+4,1), substr(value,n*6+5,2)
from tableA
join (select level-1 as n from dual connect by level <= 100)
on length(value) > n*6;
see Sqlfiddle.
select ID,
SUBSTR(value,number*6+1,3),
SUBSTR(value,number*6+4,1),
SUBSTR(value,number*6+5,2)
from yourtable,
(select 0 as number union select 1 union select 2 union select 3 union select 4
union select 5 union select 6) as numbers
/* etc up to the max length of your string /6 */
where LEN(value)>number*6
try this:
Please convert it to ORACLE SQL..
Even though, its using a while loop, its doing bulk inserts..and the loop is executed as per the length of maximun length of value in the table
declare #max_len int=0;
declare #counter int=0;
declare #col_index int=1;
select #max_len=MAX(len(Value)) from TableA
while (#max_len/6 > #counter)
begin
set #counter=#counter+1
Insert into TableB
select ID,substring(Value,#col_index,3),
substring(Value,#col_index+3,1),
substring(Value,#col_index+4,2)
from TableA where substring(Value,#col_index,3) is not null
set #col_index=#col_index+6
end
Using a SELECT, I want to find the row ID of 3 columns (each value is unique/dissimilar and is populated by separate tables.) Only the ID is auto incremented.
I have a middle table I reference that has 3 values: ID, A, B.
A is based on data from another table.
B is based on data from another table.
How can I select the row ID when I only know the value of A and B, and A and B are not the same value?
Do you mean that columns A and B are foreign keys?
Does this work?
SELECT [ID]
FROM tbl
WHERE A = #a AND B = #b
SELECT ID FROM table WHERE A=value1 and B=value2
It's not very clear. Do you mean this:
SELECT ID
FROM middletable
WHERE A = knownA
AND B = knownB
Or this?
SELECT ID
FROM middletable
WHERE A = knownA
AND B <> A
Or perhaps "I know A" means you have a list of values for A, which come from another table?
SELECT ID
FROM middletable
WHERE A IN
( SELECT otherA FROM otherTable ...)
AND B IN
( SELECT otherB FROM anotherTable ...)