I am trying to join 2 tables and return data if the Table1.codeId is presented on Table2 OR if Table1.codeId = 0. However, It retrieves the data from Table2.
Table1 {
name nvarchar,
codeId int
}
| name | codeId |
|--------|--------|
| Bob | 1 |
| Bob | 2 |
| Chris | 0 |
Table2 {
id int,
codeName nvarchar
}
| id | codeName |
|------|----------|
| 1 | Engineer |
| 2 | Doctor |
| 3 | Dentist |
| 4 | Pilot |
| 5 | Mechanic |
SELECT t1.name, t2.codeName
FROM dbo.Table1 t1, dbo.Table2 t2
WHERE (t1.codeId = t2.id OR t1.codeId = 0)
Expected result:
Bob, 1
John, 2
Chris, 0
You are not required to use Join at all for such condition.
You can use subquery as following, it return same result as your expectation
select name,codeid from table1 where codeid in (select id from table2)
or codeid=0
What if you do it in two separates queries ?
Looking at the outcome, the problem must come from the WHERE clause. The OR seem to always be triggered.
So maybe splitting could do it
SELECT t1.name, t2.codeName
FROM dbo.Table1 t1, dbo.Table2 t2
WHERE (t1.codeId = t2.id)
SELECT t1.name, t2.codeName
FROM dbo.Table1 t1, dbo.Table2 t2
WHERE (t1.codeId = 0)
You can use a left join. Use it to select where there is a code match in Table2 or the code_id is 0.
create table Table1
(
name nvarchar(50),
codeId int
)
create table Table2
(
id int,
codeName nvarchar(50)
)
insert into Table1
VALUES
('Bob', 1),
('John', 2),
('Chris', 0),
('Tom', -1)
-- This should be excluded .. since -1 code doesn't exist in Table2
insert into Table2
VALUES
(1, 'Engineer'),
(2, 'Doctor'),
(3, 'Dentist'),
(4, 'Pilot'),
(5, 'Mechanic')
SELECT t1.name, t1.codeId
FROM dbo.Table1 t1
LEFT JOIN dbo.Table2 t2 ON t1.codeId = t2.id
WHERE t2.id is not NULL or t1.codeId = 0
You have to use left outer join.
please find below query
Select codeid,name
FROM Table1
LEFT OUTER JOIN Table2
ON Table1.codeId=Table2.id;
Related
I'm trying to find a simple solution for my SQL Server problem.
I have two tables look like this:
table1
--id
-- data
table2
--id
--table1_id
--value
I have some records like this:
Table1
+-----------------------+
| id | data |
+-----------------------+
| 1 | ? |
+-----------------------+
| 2 | ? |
+-----------------------+
Table2
+-----------------------+
|id | table1_id | value |
+-----------------------+
| 1 | 1 | 'a' |
+-----------------------+
| 2 | 1 | 'b' |
+-----------------------+
| 3 | 2 | 'a' |
+-----------------------+
Now I want to get table1 with all it's additional values where the relation to table2 has 'a' AND 'b' as values.
So I would get the id 1 of table1.
Currently I have an query like this:
SELECT t1.[id], t1.[data]
FROM [table1] t1,
(SELECT [id]
FROM [table1] t1
JOIN [table2] t2 ON t1.[id] = t2.[table1_id] AND t2.[Value] IN('a', 'b')
GROUP BY t1[id]
HAVING COUNT(t2.[Value]) = 2) x
WHERE t1.id = x.id
Has anyone an idea on how to achieve my goal in a simpler way?
One way uses exists:
select t1.*
from table1 t1
where exists (select 1
from table2 t2
where t2.table1_id = t1.id and t2.value = 'a'
) and
exists (select 1
from table2 t2
where t2.table1_id = t1.id and t2.value = 'b'
);
This can take advantage of an index on table2(table1_id, value).
You could also write:
select t1.*
from table1 t1
where (select count(distinct t2.value)
from table2 t2
where t2.table1_id = t1.id and t2.value in ('a', 'b')
) = 2 ;
This would probably also have very good performance with the index, if table2 doesn't have duplicates.
SELECT T1.[id], T1.[data]
FROM table1 AS T1
JOIN table2 AS T2
ON T1.[id]=T2.[table1_id]
JOIN table2 AS T3
ON T1.[id]=T3.[table1_id]
WHERE
T2.[Value] ='a'
AND T3.[Value] = 'b'
As Gordon Linoff suggested, exists clause usage works as well and could be performance efficient depending on the data you are playing with.
you have to do several steps to solve the problem:
established which records are related to table 1 and table 2 and which of these are of value (A or B) and eliminate the repeated ones with the group by(InfoRelationate )
validate that only those related to a and b were allowed by means of a count in the table above (ValidateAYB)
see what data meets the condition of table1 and table 2 and joined table 1
this query meets the conditions
with InfoRelationate as
(
select Table2.table1_id,value
from Table2 inner join
Table1 on Table2.table1_id=Table1.id and Table2.value IN('a', 'b')
group by Table2.table1_id,value
),
ValidateAYB as
(
select InfoRelationate.table1_id
from InfoRelationate
group by InfoRelationate.table1_id
having count (1)=2
)
select InfoRelationate.table1_id,InfoRelationate.value
from InfoRelationate
inner join ValidateAYB on InfoRelationate.table1_id=ValidateAYB.table1_id
union all
select id,data
from Table1
Example code
------------------
| **table 1** |
------------------
| 1 | 400 |
| 2 | 220 |
| 3 | 123 |
------------------
| **table 2** |
------------------
| 1 | 100 |
formula : table1 - table2 where table1.id=table2.id
------------------
| **Result** |
------------------
| 1 | 300 |
| 2 | 220 |
| 3 | 123 |
You want an outer join to get all rows from table_1 and the matching ones from table2
select t1.id, t1.val - coalesce(t2.val, 0) as result
from table_1 t1
left join table_2 t2 on t1.id = t2.id;
The coalesce(t2.val, 0) is necessary because the outer join will return null for those rows where no id exists in table_2 but t1.val - null would yield null
select t1.id,
nvl2(t2.val,t1.val-t2.val,t1.val) val
from t1,t2
where t1.id=t2.id(+)
order by t1.id;
Try this
select t1.col1, t1.col2-t2.col1 as balance from
table1 t1 left join table2 t2 on t1.col1=t2.col1
I don't the syntax in Oracle sql, but I can give the solution in mysql.
Consider the table with 2 columns:
id , value
SELECT table1.id, table1.value - table2.value
FROM table1, table2
WHERE table1.id=table2.id
OR
SELECT table1.id, table1.value
FROM table1, table2
WHERE NOT (table1.id =table2.id)
In some cases using scalar subquery caching could give better performance. It is on developer to compare execution plans and decide which query is the most appropriate.
with t1 (id, num) as
(
select 1, 400 from dual union all
select 2, 220 from dual union all
select 3, 123 from dual
),
t2(id, num) as
(
select 1, 100 from dual
)
select id,
num - nvl((select num from t2 where t2.id = t1.id), 0) result
from t1;
This is just to show you a different technique for solving problems in which you try to get data from several tables, but some may not have matching rows.
Using outer join in this case is in my opinion more logical.
I got a problems in combining tables
I have 2 table:
t1:
id | name
----- ---------
1 | 'foo'
2 | 'bar'
t2:
id | type
------ ---------
1 | 'type1'
3 | 'type2'
I want to combine those tables into 1 result set and make all attributes of same primary key in 1 row. And with single SQL statement in Oracle. The primary key column with the same name (id in the sample) can't appear twice
The result should be:
id | name | type
----- --------- ---------
1 | 'foo' | 'type1'
2 | 'bar' | null
3 | null | 'type2'
Thanks in advance for any ideas and responses.
Update:
I tried Ani Menon's out join statement, but not 100% the expected result. The outer join gives null value if id exists in t1 but not in t2.
SELECT t1.id,t1.name,t2.type
FROM t1
FULL OUTER JOIN t2 ON t1.id=t2.id;
Returns
id | name | type
----- --------- ---------
1 | 'foo' | 'type1'
2 | 'bar' | null
null | null | 'type2'
Do a full outer join:
SELECT table1.id,table1.name,table2.type
FROM table1
FULL OUTER JOIN table2 ON table1.id=table2.id;
Edit:
Use coalesce(table1.id,table2.id) in place of table1.id in the query.
Similar to Ani's answer, but won't give you the null id:
select coalesce(table1.id, table2.id) as id, table1.name, table2.type
from table1 full outer join table2 on table1.id = table2.id;
might now be the optimal solution but this will work.
select allIDs.id, t1.name, t2.type
(select id from t1
union
select id from t2) allIDs left outer join t1 on allIDs.id = t1.id left outer join t2 on allIDs.id = t2.id
tested in sql server worked.
create table t1 (
id int,
name varchar(25)
)
create table t2
(
id int,
type varchar(25)
)
insert into t1
values(1, 'fool'),
(2,'bar')
insert into t2
values(1,'type1'),
(3,'type2')
select id, MAX(name) name, MAX(type) type from(
select id, name, null type from t1
union all
select id, null name, type from t2) combine group by id
SELECT t1.id,t1.name,t2.type
FROM t1
LEFT OUTER JOIN t2 ON t1.id=t2.id
union
select t2.id, t1.name, t2.type
from t2
left outer join t1 on t2.id = t1.id
I have the following structure:
TABLE1 TABLE2
id_worker_main id_worker
id_worker_sub name_worker
I need to make a select getting the name_worker for both id_worker_main and id_worker_sub, but I can't. The following query return the same name twice.
SELECT t2.name_worker as main, t2.name_worker as sub
FROM table1
INNER JOIN table2 ON t1.id_worker_main = t2.id_worker AND t1.id_worker_sub = t2.id_worker
You have to join with the same table twice. Just use a different alias for each join
Sql Fiddle Demo
With this workers
INSERT INTO Table2
([id_worker], [name_worker])
VALUES
(1, 'Juan'),
(2, 'Angela'),
(3, 'Peter');
And this relationship
INSERT INTO Table1
([id_worker_main], [id_worker_sub])
VALUES
(1, 2),
(2, 3),
(1, 3);
Use this query
SELECT A.name_worker MAINWORKER, B.name_worker SUBWORKER
FROM Table1 T1
Inner join Table2 A
ON T1.id_worker_main = A.id_worker
Inner join Table2 B
ON T1.id_worker_sub = B.id_worker
OUTPUT
| MAINWORKER | SUBWORKER |
|------------|-----------|
| Juan | Angela |
| Angela | Peter |
| Juan | Peter |
If I understood your problem correctly, you can join table2 multiple times
SELECT t21.name_worker as main, t22.name_worker as sub
FROM table1 t1
JOIN table2 t21 on t21.id_worker = t1.id_worker_main
JOIN table2 t22 on t22.id_worker = t1.id_worker_sub
Assuming I have a table containing the following information:
FK | Field1 | Field2
=====================
3 | ABC | *NULL*
3 | *NULL* | DEF
is there a way I can perform a select on the table to get the following
FK | Field1 | Field2
=====================
3 | ABC | DEF
Thanks
Edit: Fix field2 name for clarity
Aggregate functions may help you out here. Aggregate functions ignore NULLs (at least that's true on SQL Server, Oracle, and Jet/Access), so you could use a query like this (tested on SQL Server Express 2008 R2):
SELECT
FK,
MAX(Field1) AS Field1,
MAX(Field2) AS Field2
FROM
table1
GROUP BY
FK;
I used MAX, but any aggregate which picks one value from among the GROUP BY rows should work.
Test data:
CREATE TABLE table1 (FK int, Field1 varchar(10), Field2 varchar(10));
INSERT INTO table1 VALUES (3, 'ABC', NULL);
INSERT INTO table1 VALUES (3, NULL, 'DEF');
INSERT INTO table1 VALUES (4, 'GHI', NULL);
INSERT INTO table1 VALUES (4, 'JKL', 'MNO');
INSERT INTO table1 VALUES (4, NULL, 'PQR');
Results:
FK Field1 Field2
-- ------ ------
3 ABC DEF
4 JKL PQR
There are a few ways depending on some data rules that you have not included, but here is one way using what you gave.
SELECT
t1.Field1,
t2.Field2
FROM Table1 t1
LEFT JOIN Table1 t2 ON t1.FK = t2.FK AND t2.Field1 IS NULL
Another way:
SELECT
t1.Field1,
(SELECT Field2 FROM Table2 t2 WHERE t2.FK = t1.FK AND Field1 IS NULL) AS Field2
FROM Table1 t1
There might be neater methods, but the following could be one approach:
SELECT t.fk,
(
SELECT t1.Field1
FROM `table` t1
WHERE t1.fk = t.fk AND t1.Field1 IS NOT NULL
LIMIT 1
) Field1,
(
SELECT t2.Field2
FROM `table` t2
WHERE t2.fk = t.fk AND t2.Field2 IS NOT NULL
LIMIT 1
) Field2
FROM `table` t
WHERE t.fk = 3
GROUP BY t.fk;
Test Case:
CREATE TABLE `table` (fk int, Field1 varchar(10), Field2 varchar(10));
INSERT INTO `table` VALUES (3, 'ABC', NULL);
INSERT INTO `table` VALUES (3, NULL, 'DEF');
INSERT INTO `table` VALUES (4, 'GHI', NULL);
INSERT INTO `table` VALUES (4, NULL, 'JKL');
INSERT INTO `table` VALUES (5, NULL, 'MNO');
Result:
+------+--------+--------+
| fk | Field1 | Field2 |
+------+--------+--------+
| 3 | ABC | DEF |
+------+--------+--------+
1 row in set (0.01 sec)
Running the same query without the WHERE t.fk = 3 clause, it would return the following result-set:
+------+--------+--------+
| fk | Field1 | Field2 |
+------+--------+--------+
| 3 | ABC | DEF |
| 4 | GHI | JKL |
| 5 | NULL | MNO |
+------+--------+--------+
3 rows in set (0.01 sec)
I had a similar problem. The difference was that I needed far more control over what I was returning so I ended up with an simple clear but rather long query. Here is a simplified version of it based on your example.
select main.id, Field1_Q.Field1, Field2_Q.Field2
from
(
select distinct id
from Table1
)as main
left outer join (
select id, max(Field1)
from Table1
where Field1 is not null
group by id
) as Field1_Q on main.id = Field1_Q.id
left outer join (
select id, max(Field2)
from Table1
where Field2 is not null
group by id
) as Field2_Q on main.id = Field2_Q.id
;
The trick here is that the first select 'main' selects the rows to display. Then you have one select per field. What is being joined on should be all of the same values returned by the 'main' query.
Be warned, those other queries need to return only one row per id or you will be ignoring data
if one row has value in field1 column and other rows have null value then this Query might work.
SELECT
FK,
MAX(Field1) as Field1,
MAX(Field2) as Field2
FROM
(
select FK,ISNULL(Field1,'') as Field1,ISNULL(Field2,'') as Field2 from table1
)
tbl
GROUP BY FK
My case is I have a table like this
---------------------------------------------
|company_name|company_ID|CA | WA |
---------------------------------------------
|Costco | 1 |NULL | 2 |
---------------------------------------------
|Costco | 1 |3 |Null |
---------------------------------------------
And I want it to be like below:
---------------------------------------------
|company_name|company_ID|CA | WA |
---------------------------------------------
|Costco | 1 |3 | 2 |
---------------------------------------------
Most code is almost the same:
SELECT
FK,
MAX(CA) AS CA,
MAX(WA) AS WA
FROM
table1
GROUP BY company_name,company_ID
The only difference is the group by, if you put two column names into it, you can group them in pairs.
SELECT Q.FK
,ISNULL(T1.Field1, T2.Field2) AS Field
FROM (SELECT FK FROM Table1
UNION
SELECT FK FROM Table2) AS Q
LEFT JOIN Table1 AS T1 ON T1.FK = Q.FK
LEFT JOIN Table2 AS T2 ON T2.FK = Q.FK
If there is one table, write Table1 instead of Table2