Hi there basically i have 2 tables with 162 entries and im trying to populate a new table with entries from the other tables to show the difference between a number value
Insert Into popdiff(
popdiff)
select (a.malepop+a.femalepop)-(b.malepop+b.femalepop)
from tablea a, tableb b;
The problem im having is it is returning 26244 results i.e. 162*162 rather than 162 which im expecting, having looked into it a bit the query is finding the value for each entry in tablea- the 162 values in tableb
how can i simply return just the 162 rows?
You didn't specify the relationship between the two tables and that's a cross join which returns what you described. Specify the relationship either in a WHERE condition or a JOIN condition.
WHERE:
SELECT (a.malepop+a.femalepop)-(b.malepop+b.femalepop)
FROM tablea a, tableb b;
WHERE a.id = b.id;
JOIN:
SELECT (a.malepop+a.femalepop)-(b.malepop+b.femalepop)
FROM tablea a
INNER JOIN tableb b ON a.id = b.id;
Of course, you may have different names for the IDs, so change the a.id = b.id consition accordingly.
You have to do an inner join:
select (a.malepop+a.femalepop)-(b.malepop+b.femalepop)
from tableA join tableB using (field)
That will do the job
Related
I have some doubt in MySQL joins
I have 2 tables for example TableA,TableB
TableA primary key is Foreign key of Table B
So I'm using inner join to get matched values but TableB have one column for row activate status so all active status is zero means I need to get that record or else I need to skip that record.
My query:.
Select * From TableA a inner join TableB b on a.id=b.aid where b.isActive=0;
The above query was return value if any one value is true
For example any one of is active row true. But I need to check all row is zero if it's all value zero means I need to return that so how I do that..?
Thanks in advance.
Select a.*
From TableA a
where not exists(SELECT 1 FROM TableB b WHERE a.id=b.aid AND b.isActive=1);
You can use your query change the filter as follows:
SELECT * FROM TableA a
JOIN TableB b ON a.id=b.aid
WHERE a.id NOT IN(SELECT aid FROM TableB WHERE isActive=1)
I have 3 tables A, B, C
Schema of all 3 tables is same as mentioned below:
1st A table:
cpid ,name, place
2nd B table:
connectorid,dob
3rd C table:
ccpid cconnectorid
Now both tables A and B have many records.
Now some of the records in A and B are with same id.
Now I want to merge the records from A and B into Table C.
Merge logic is as follows
1)If records with cpid = connectorid ,insert into table c.
2)C Table ccpid is the foreignkey for A table cpid and cconnectorid is the foreignkey B table connectorid.
3)Using select query.
You can use select insert with a n inner join
insert into table_c
select a.cpid, b.connectorid, a.place
from table_b as b
inner join table_a as a on a.id = b.id
You can try this solution for your query:
INSERT INTO `C`(`ccpid`, `cconnectorid`, `ccity`)
SELECT ta.`cpid`, ta.`cconnectorid`, tb.`place`
FROM `A` as ta
INNER JOIN `B` tb ON ta.`cpid` = tb.`cconnectorid`
You just need join data from both tables? This is simple JOIN function.
SELECT *
FROM Table_A
INNER JOIN Table_B
ON Table_A.cpid =Table_B.connectorid;
You can insert this select to your Table_C.
Here is INNER JOIN, but I think you should take a look to JOINs, here are examples and you can read more about other JOINs.
INNER JOIN: Returns all rows when there is at least one match in BOTH
tables LEFT JOIN: Return all rows from the left table, and the matched
rows from the right table RIGHT JOIN: Return all rows from the right
table, and the matched rows from the left table FULL JOIN: Return all
rows when there is a match in ONE of the tables
use following query replace with your table names
INSERT INTO CTABLE(ccpid,cconnectorid,ccity)
(SELECT A.cpid ,B.connectorid, A.place FROM
TABLEA A INNER JOIN TABLEB B ON A.cpid = B.connectorid)
I have two tables lets say
Table A
columns id , name address
Table B
columns id , age, import_date
The Table B id is a reference key of Table A.
Now I want to return results from A & B but if the record is not in B I still want to see the record so for this I use left outer join
Select * from A a left join B b
on a.id = b.id
Now even I don't have record in B I still get the record.
Table B may contain duplicate ids but unique import_date.
Now I want to results in a way that if there is duplicate id in table B then I want to get the records only where import_date is as of today.
I still want to get the records for ids which are not there but if the ID is there in table B then I want to apply above condition.
I hope someone can help me with this.
Sample data
Table A
01|John|London
02|Matt|Glasgow
03|Rodger|Paris
Table B
02|22|31-AUG-2015
02|21|30-AUG-2015
02|23|29-AUG-2015
The query will return
01|John|London|null|null|null
02|Matt|Glasgow|22|31-Aug-2015
03|Rodger|Paris|null|null
You almost got the solution. Just add one more condition like below
Select a.id,a.name,a.address,b.age,b.import_date
from tablea a left join tableb b
on a.id=b.id and b.import_date=trunc(sysdate)
order by a.id;---This line optional
Check the DEMO HERE
SELECT *
FROM Table_A t1 LEFT OUTER JOIN Table_B t2 ON t1.id=t2.id UNION
SELECT *
FROM Table_A t1 LEFT OUTER JOIN Table_B t2 ON t1.id=t2.id
GROUP BY t2.import_date
HAVING t2.import_date=CURDATE();
I have 2 MySQL tables A and B.
I would like to select only the records from B where a certain value exists in A.
Example:
A has columns: aID, Name
B has columns: bID, aID, Name
I just want the records from B for which aID exists in A.
Many thanks.
You need to do either INNER JOIN - records that exists in both tables, or use LEFT join, to show records that exists in A and matching IDs exists in B
A good reference:
You need to make a join, and if you don't want to retrieve anything from table b, just return values from table a.
This should work
select b.* from b join a on b.aID=a.aID
Below query will also work and will be effective
SELECT * FROM B
WHERE B.aID IN (SELECT DISTINCT aID FROM A)
You just need a simple inner join between tables A and B. Since they are related on the aID column, you can use that to join them together:
SELECT b.*
FROM tableB b
JOIN tableA a ON a.aID = b.aID;
This will only select rows in which the aID value from tableB exists in tableA. If there is no connection, the rows can't be included in the join.
While I recommend using a join, you can also replace it with a subquery, like this:
SELECT *
FROM tableB
WHERE aID NOT IN (SELECT aID FROM tableA)
You can use join like this.
Select b.col1,b.col2... From tableB b inner join table tableA a on b.field = a.field
Have you tried using a LEFT JOIN?
SELECT b.* FROM tableB b LEFT JOIN tableA a ON b.aID = a.aID
I have two tables with exactly the same fields. Table A contains 7160 records and table B 7130 records.Now I want to insert distinct records from table A into table B such that B should not have any duplicate entry in it. How should I go about doing this?
This basically selects records that are in A that are not in B. It would work, but you might have to tweak the field you use to uniquely identify a record. In this example I used field 'ID' but you might have to change that to A.field1 = B.field1 AND A.field2 = B.field2 etc.
INSERT INTO TABLEB
(
SELECT A.*
FROM TABLEA A
LEFT JOIN TABLEB B ON A.ID = B.ID
WHERE B.ID IS NULL
)
You can use a "union" query to combine the results from multiple tables into a single result set. "union" will only return distinct rows from all tables.
See this page for more info:
http://www.tutorialspoint.com/mysql/mysql-union-keyword.htm
insert into tableB (id)
select t1.id from tableA t1
where t1.id not in (select t2.id from tableB t2)