I'm trying to create a table in sas that will take observations from a specific column as long as they aren't list in another column in another table.
I've used the code:
proc sql;
create table tbl as
select a.var1, a.var2, a.var3 from
tblA as a, tblB as b
where a.var1~=b.var1;
quit;
Would it be because I've assigned b as a table I'm not selecting a variable from? or is my condition just incorrect?
Your condition is incorrect, you need to tell the tables how to join (where the equality is) THEN tell them that you only want those that dont match.
A left join is used for this:
select a.var1, a.var2, a.var3
from
tblA as a
left join tblB as b on a.var1 = b.var1
where
b.var1 is null
Where a are the values you want that dont match b.
See SAS SQL join examples for more
This can also be accomplished using NOT IN
Related
I'm trying to take the distinct IDs that appear in table a, filter table b for only these distinct IDs from table a, and present the remaining columns from b. I've tried:
SELECT * FROM
(
SELECT DISTINCT
a.ID,
a.test_group,
b.ch_name,
b.donation_amt
FROM table_a a
INNER JOIN table_b b
ON a.ID=b.ID
ORDER by a.ID;
) t
This doesn't seem to work. This query worked:
SELECT DISTINCT a.ID, a.test_group, b.ch_name, b.donation_amt
FROM table_a a
inner join table_b b
on a.ID = b.ID
order by a.ID
But I'm not entirely sure this is the correct way to go about it. Is this second query only going to take unique combinations of a.ID and a.test_group or does it know to only take distinct values of a.ID which is what I want.
Your first and second query are similar.(just that you can not use ; inside your query) Both will produce the same result.
Even your second query which you think is giving you desired output, can not produce the output what you actually want.
Distinct works on the entire column list of the select clause.
In your case, if for the same a.id there is different a.test_group available then it will have multiple records with same a.id and different a.test_group.
Lets say I have a query where one field can appear in either Table A or Table B but not both. So to retrieve it I use Coalesce.
Something like
Select
...
Coalesce(A.Number,B.Number) Number
...
From Table A
Left Join Table B on A.C= B.C
Now lets say I want to join another table to that Number field
should I just do
Join Table Z on Z.Z = Coalesce(A.Number,B.Number)
Or is it better to wrap my original table in a query and join on the definite result. So something like
Select * from (
Select
...
Coalesce(A.Number,B.Number) Number
...
From Table A
Left Join Table B on A.C= B.C
) T
left join Table Z on Z.Number= T.Number
Does this make a difference?
if i were joining another table to the result of the first query instead of a sub query i would place the first part in a CTE whenever possible, i believe the performance would be the same as a subquery but CTEs are more readable in my opinion.
with cte1 as
(
Select
...
Coalesce(A.Number,B.Number) Number
...
From Table A
Left Join Table B
on A.C= B.C
)
select *
from cte1 a
Join Table Z
on Z.Z = a.number
I have the following issue on SQL.
What I have (table A and table B)
What I want
My aim is to have a third table with the name of the file.
Info: my tables do not have any keys.
I've tried the code but it is not doing what I want
create table correspondance as
select b.var1, a.var1, a.var2
from A a
inner join B b on a.var1 = b.var2;
Any insights are welcomed.
Edited
I have this result :
var1 var2
azdt.csv fich11.csv
zlata.csv fich13.csv
You're just joining on the wrong fields, and too many fields selected
select a.var1, b.var2
from A a
inner join B b on a.var2 = b.var1
I'm a newbie, just learning SQL and have this question: I have two tables with the same columns. Some registers are in the two tables but others only are in one of the tables. To illustrate, suppose table A = (1,2,3,4), table B=(3,4,5,6), numbers are registers. I need to select all registers in table B if they are not in table A, that is result=(5,6). What query should I use? Maybe a join. Thanks.
You can either use a NOT IN query like this:
SELECT col from A where col not in (select col from B)
or use an outer join:
select A.col
from A LEFT OUTER JOIN B on A.col=B.col
where B.col is NULL
The first is easier to understand, but the second is easier to use with more tables in the query.
Select register from TABLE_B b
Where not exists (Select register from TABLE_A a where a.register = b.register)
I assumed you have a column named register in TABLE_A and TABLE_B
Hello I Have a problem in getting rows from one table after comparing both. Detail of Both Table are as follows:-
I am using Ms Access database.
TableA is having a data of numeric type (Field Name is A it is primary key)
----------
Field A
==========
1
2
3
4
5
Table B is having data of numeric type ( Field Name is A it is foreign key)
--------
Field A
========
2
4
Now I am using below query which is this
select a.a
from a a
, b b
where a.a <> b.b
I want to show all the data from Table A which is not equal to Table B. But the above query is not working as I described.
Can you help me in this regard.
Regards,
Fawad Munir
In an attempt at clarity, I've used upper case for tables and lower case for fields:
Select A.a
FROM A LEFT OUTER JOIN B ON A.a=B.b
WHERE B.b is null
This will show all the records in A that are not in B (I assume that's what you want).
Read up on Access outer joins. In the query designer you double click the join and select something like "all records from table a and only the matching records in table b".
In your question you said that the name of the field in table B is 'A'. Given that, I'd say that your query should be something like
select a.a
from a, b
where a.a <> b.a
But I'm not sure this will do what you want. I think you're trying to find rows in table A which do not have a matching row in table B, in which case you might try
SELECT A.A
FROM A
LEFT OUTER JOIN B
ON (B.A = A.A)
WHERE B.A IS NULL
Try that and see if it does what you want.
Share and enjoy.
I don't know exactly if Access would accept the syntax, but here how I would do in SQL Server.
select a.a
from TableA a
where a.a NOT IN (
select b.a
from TableB b
)
or even as above-mentioned:
select a.a
from TableA a
left outer join TableB b on b.a = a.a
where b.a IS NULL
Its not entirely clear what you are trying to achieve, but its sounds like you are attempting to solve the common problem of finding rows in Table A missing associated data in Table B. If this is the case, it appears you misunderstand the semantics of the join you tried. In which case, you have 2 problems, because the understanding the the JOIN operation is critical to working with relational databases.
In relation to the first problem, please research how to express a subquery using the IN operator. Something like
... WHERE a NOT IN (SELECT a from b)
In relation to the second problem, try your query without the WHERE restriction, and see what is returned. Once you understand what the join is doing, you will see why applying a WHERE restriction to it will not solve your problem.
If I understand you correctly, you want to see every row in A for which column a contains a value that cannot be found in any column b value of B. You can get this data in several ways.
I think using NOT IN is the clearest, personally:
SELECT * FROM tableA WHERE columnA NOT IN
(SELECT columnB FROM tableB WHERE columnB IS NOT NULL)
Many people prefer a filtered JOIN:
SELECT tableA.* FROM tableA LEFT OUTER JOIN tableB
ON tableA.columnA = tableB.columnB WHERE tableB.columnB IS NULL
There is a NOT EXISTS variant as well:
SELECT * FROM tableA WHERE columnA NOT EXISTS
(SELECT * FROM tableB WHERE columnB = tableA.columnA)