How can I check if all the items in one table exists within another. For example, consider the following two tables.
With their respective query:
SELECT orderID
FROM orders
WHERE customer_id = 1;
TABLE A
-------
orderID
2
1
6
4
SELECT orderID
FROM orders
WHERE customer_id = 2;
TABLE B
-------
orderID
5
1
7
9
I would not want to output anything because all the items from TABLE A do not exist within TABLE B.
However, I were to have:
SELECT orderID
FROM orders
WHERE customer_id = 3;
TABLE C
-------
orderID
5
I would want to output it because all the items within TABLE C are in TABLE B.
If I were to do a select with TABLE C, I would expect table C to be the output.
I have tried the following query:
SELECT *
FROM (SELECT orderID
FROM orders
WHERE customer_id = 1) A
WHERE A.orderID IN (
SELECT orderID
FROM orders
WHERE customer_id = 2);
If you can to check in a by-customer basis, you can do this:
IF (NOT EXISTS
SELECT NULL
FROM orders
WHERE customer_id = 1 -- "Table A"
AND orderID NOT IN
-- "Table B"
(SELECT orderID
FROM orders
WHERE customer_id = 2)
)
SELECT orderID
FROM orders
WHERE customer_id = 1;
Here the query basically gets the orders from table A which are not in table B. If there is none, it then performs the select at the end. Otherwise, it does nothing.
If you use customer_id = 3 instead, you get one row with orderID 5 ("table C").
One approach would be to left join a table with TABLE B and look for nulls in the resulting sub-query. Here is some (untested) pseudo code:
SELECT *
FROM (
SELECT
table_B.orderID
FROM table_A
LEFT JOIN table_B ON table_A.orderID=table_B.orderID
) x WHERE x.orderID IS NULL
Any rows from table_A that don't have a match in table_B will have a NULL value as table_B.orderID. The outer select you may have to change depending on what type of output you are looking for, but hopefully the principal helps.
I have two tables customers and orders, below is the structure.
Table - contacts
id
Table - orders
id
contact_id
How can I select all from contacts table but only select the latest record from the orders table?
SELECT contacts.*,
Max(orders.id)
FROM contacts
LEFT JOIN orders
ON contacts.id = orders.contact_id
GROUP BY contacts.id;
But I always gets NULL if I use LEFT JOIN, it only have value if I use INNER JOIN.
select the latest record in orders and group it first
select contacts.*, orders.id
from contacts
left join (select max(id) as id, contact_id
from orders
group by contact_id) orders
on contacts.id = orders.contact_id
You can try to use UNION like
select * from orders order by id desc limit 1
UNION
select * from contacts
In order to aggregate max value with all columns from contacts table, add all columns from contacts table after group by function
I trust the answer provided by Alex should work well. The following query shall list all records from contacts and the last id from orders table.
SELECT
c.*,
(SELECT Max(o.id) FROM orders o
INNER JOIN contacts c1 ON o.id=c1.id
)as last_order_id
FROM contacts c
I have two tables Customers and Customer_orders. I'm trying to SELECT customer's order by using Customer_ID from Customer table.
SELECT * FROM Customer_orders WHERE Customer_ID = SELECT ID FROM Customers WHERE Customer_name = 'John Doe'
This code does not work. How do I do this?
You need to JOIN those 2 tables and then query for what you need. Like this:
SELECT co.*
FROM Customer_orders co
INNER JOIN Customers c ON co.Customer_ID = c.ID
WHERE c.Customer_name = 'John Doe';
The other answer is a little complex - it might attempt to show you a solution that can solve a more difficult problem.
First, it queries the ID of the John Doe from Customer table.
Second, it queries the all columns from Customer_orders table where customer_id equals ID.
My solution is easy:
SELECT * FROM Customer_orders WHERE Customer_ID in (SELECT ID FROM Customers WHERE Customer_name = 'John Doe')
or
SELECT * FROM Customer_orders WHERE Customer_ID = (SELECT ID FROM Customers WHERE Customer_name = 'John Doe')
Generally, ID is a primary key of Customer table and the customer_id should be a key index of the Customer_orders.
Two times query of single table using key index is faster than the query using join operation especially when the tables have too many rows.
And thanks Tim to correct my grammar. I so appreciate it. My English is not good .
you can use join method (inner / left) or even subquery (but not recommend to use this on this problem)
here example
inner join
SELECT cust_order.* FROM Customer_orders cust_order, Customers cust WHERE cust_order.Customer_ID = cust.ID AND cust.Customer_name = 'John Doe'
left join
SELECT cust_order.* FROM Customer_orders cust_order LEFT JOIN Customers cust ON cust_order.Customer_ID = cust.ID WHERE cust.Customer_name = 'John Doe'
sub query
SELECT * FROM Customer_orders WHERE Customer_ID = (SELECT ID FROM Customers WHERE Customer_name = 'John Doe')
make sure you only have 1 ID on table Customers if you want to use sub query, or if it have more than 1 ID, you can use "IN" instead of "="
I have two MySQL tables: 'invoice' and 'credit_memo'
I would like to combine them and list one result ordered by date.
invoice:
ID INT
date DATETIME
customer_id INT
credit_memo:
ID INT
date DATETIME
customer_id INT
My final attempt:
(SELECT ID AS invoice_number FROM invoice)
UNION
(SELECT ID AS credit_memo_number FROM credit_memo)
ORDER BY date
The problem is that both the invoice_number and credit_memo_number get put into the invoice_number variable. So when I run the result it all looks like its coming from the 'invoice' table.
How can I determine which table each particular row is pulling from?
Thank you,
Andy
Here is how you will approach it.
Both tables have customer ID so we can join them through that:
SELECT i.ID AS invoice_number,c.ID AS credit_memo_number
FROM invoice i
JOIN credit_memo c ON c.customer_id = i.customer_id
ORDER BY i.date ASC
This will select the invoice ID and the credit ID and order them by the Invoice date.
select id, t.table_name from invoice join information_schema.tables t on t.table_name='invoice'
union
select id, t.table_name from credit_memo join information_schema.tables t on t.table_name='credit_memo'
I want to pull out duplicate records in a MySQL Database. This can be done with:
SELECT address, count(id) as cnt FROM list
GROUP BY address HAVING cnt > 1
Which results in:
100 MAIN ST 2
I would like to pull it so that it shows each row that is a duplicate. Something like:
JIM JONES 100 MAIN ST
JOHN SMITH 100 MAIN ST
Any thoughts on how this can be done? I'm trying to avoid doing the first one then looking up the duplicates with a second query in the code.
The key is to rewrite this query so that it can be used as a subquery.
SELECT firstname,
lastname,
list.address
FROM list
INNER JOIN (SELECT address
FROM list
GROUP BY address
HAVING COUNT(id) > 1) dup
ON list.address = dup.address;
SELECT date FROM logs group by date having count(*) >= 2
Why not just INNER JOIN the table with itself?
SELECT a.firstname, a.lastname, a.address
FROM list a
INNER JOIN list b ON a.address = b.address
WHERE a.id <> b.id
A DISTINCT is needed if the address could exist more than two times.
I tried the best answer chosen for this question, but it confused me somewhat. I actually needed that just on a single field from my table. The following example from this link worked out very well for me:
SELECT COUNT(*) c,title FROM `data` GROUP BY title HAVING c > 1;
Isn't this easier :
SELECT *
FROM tc_tariff_groups
GROUP BY group_id
HAVING COUNT(group_id) >1
?
select `cityname` from `codcities` group by `cityname` having count(*)>=2
This is the similar query you have asked for and its 200% working and easy too.
Enjoy!!!
Find duplicate users by email address with this query...
SELECT users.name, users.uid, users.mail, from_unixtime(created)
FROM users
INNER JOIN (
SELECT mail
FROM users
GROUP BY mail
HAVING count(mail) > 1
) dupes ON users.mail = dupes.mail
ORDER BY users.mail;
we can found the duplicates depends on more then one fields also.For those cases you can use below format.
SELECT COUNT(*), column1, column2
FROM tablename
GROUP BY column1, column2
HAVING COUNT(*)>1;
Finding duplicate addresses is much more complex than it seems, especially if you require accuracy. A MySQL query is not enough in this case...
I work at SmartyStreets, where we do address validation and de-duplication and other stuff, and I've seen a lot of diverse challenges with similar problems.
There are several third-party services which will flag duplicates in a list for you. Doing this solely with a MySQL subquery will not account for differences in address formats and standards. The USPS (for US address) has certain guidelines to make these standard, but only a handful of vendors are certified to perform such operations.
So, I would recommend the best answer for you is to export the table into a CSV file, for instance, and submit it to a capable list processor. One such is LiveAddress which will have it done for you in a few seconds to a few minutes automatically. It will flag duplicate rows with a new field called "Duplicate" and a value of Y in it.
Another solution would be to use table aliases, like so:
SELECT p1.id, p2.id, p1.address
FROM list AS p1, list AS p2
WHERE p1.address = p2.address
AND p1.id != p2.id
All you're really doing in this case is taking the original list table, creating two pretend tables -- p1 and p2 -- out of that, and then performing a join on the address column (line 3). The 4th line makes sure that the same record doesn't show up multiple times in your set of results ("duplicate duplicates").
Not going to be very efficient, but it should work:
SELECT *
FROM list AS outer
WHERE (SELECT COUNT(*)
FROM list AS inner
WHERE inner.address = outer.address) > 1;
This will select duplicates in one table pass, no subqueries.
SELECT *
FROM (
SELECT ao.*, (#r := #r + 1) AS rn
FROM (
SELECT #_address := 'N'
) vars,
(
SELECT *
FROM
list a
ORDER BY
address, id
) ao
WHERE CASE WHEN #_address <> address THEN #r := 0 ELSE 0 END IS NOT NULL
AND (#_address := address ) IS NOT NULL
) aoo
WHERE rn > 1
This query actially emulates ROW_NUMBER() present in Oracle and SQL Server
See the article in my blog for details:
Analytic functions: SUM, AVG, ROW_NUMBER - emulating in MySQL.
This also will show you how many duplicates have and will order the results without joins
SELECT `Language` , id, COUNT( id ) AS how_many
FROM `languages`
GROUP BY `Language`
HAVING how_many >=2
ORDER BY how_many DESC
SELECT firstname, lastname, address FROM list
WHERE
Address in
(SELECT address FROM list
GROUP BY address
HAVING count(*) > 1)
select * from table_name t1 inner join (select distinct <attribute list> from table_name as temp)t2 where t1.attribute_name = t2.attribute_name
For your table it would be something like
select * from list l1 inner join (select distinct address from list as list2)l2 where l1.address=l2.address
This query will give you all the distinct address entries in your list table... I am not sure how this will work if you have any primary key values for name, etc..
Fastest duplicates removal queries procedure:
/* create temp table with one primary column id */
INSERT INTO temp(id) SELECT MIN(id) FROM list GROUP BY (isbn) HAVING COUNT(*)>1;
DELETE FROM list WHERE id IN (SELECT id FROM temp);
DELETE FROM temp;
Personally this query has solved my problem:
SELECT `SUB_ID`, COUNT(SRV_KW_ID) as subscriptions FROM `SUB_SUBSCR` group by SUB_ID, SRV_KW_ID HAVING subscriptions > 1;
What this script does is showing all the subscriber ID's that exists more than once into the table and the number of duplicates found.
This are the table columns:
| SUB_SUBSCR_ID | int(11) | NO | PRI | NULL | auto_increment |
| MSI_ALIAS | varchar(64) | YES | UNI | NULL | |
| SUB_ID | int(11) | NO | MUL | NULL | |
| SRV_KW_ID | int(11) | NO | MUL | NULL | |
Hope it will be helpful for you either!
SELECT t.*,(select count(*) from city as tt where tt.name=t.name) as count FROM `city` as t where (select count(*) from city as tt where tt.name=t.name) > 1 order by count desc
Replace city with your Table.
Replace name with your field name
SELECT id, count(*) as c
FROM 'list'
GROUP BY id HAVING c > 1
This will return you the id with the number of times that id is repeated, or nothing in which case you will not have repeated id.
Change the id in the group by (ex: address) and it will return the number of times an address is repeated identified by the first found id with that address.
SELECT id, count(*) as c
FROM 'list'
GROUP BY address HAVING c > 1
I hope it helps. Enjoy ;)
SELECT *
FROM (SELECT address, COUNT(id) AS cnt
FROM list
GROUP BY address
HAVING ( COUNT(id) > 1 ))
I use the following:
SELECT * FROM mytable
WHERE id IN (
SELECT id FROM mytable
GROUP BY column1, column2, column3
HAVING count(*) > 1
)
Most of the answers here don't cope with the case when you have MORE THAN ONE duplicate result and/or when you have MORE THAN ONE column to check for duplications. When you are in such case, you can use this query to get all duplicate ids:
SELECT address, email, COUNT(*) AS QUANTITY_DUPLICATES, GROUP_CONCAT(id) AS ID_DUPLICATES
FROM list
GROUP BY address, email
HAVING COUNT(*)>1;
If you want to list every result as a single line, you need a more complex query. This is the one I found working:
CREATE TEMPORARY TABLE IF NOT EXISTS temptable AS (
SELECT GROUP_CONCAT(id) AS ID_DUPLICATES
FROM list
GROUP BY address, email
HAVING COUNT(*)>1
);
SELECT d.*
FROM list AS d, temptable AS t
WHERE FIND_IN_SET(d.id, t.ID_DUPLICATES)
ORDER BY d.id;
Find duplicate Records:
Suppose we have table : Student
student_id int
student_name varchar
Records:
+------------+---------------------+
| student_id | student_name |
+------------+---------------------+
| 101 | usman |
| 101 | usman |
| 101 | usman |
| 102 | usmanyaqoob |
| 103 | muhammadusmanyaqoob |
| 103 | muhammadusmanyaqoob |
+------------+---------------------+
Now we want to see duplicate records
Use this query:
select student_name,student_id ,count(*) c from student group by student_id,student_name having c>1;
+--------------------+------------+---+
| student_name | student_id | c |
+---------------------+------------+---+
| usman | 101 | 3 |
| muhammadusmanyaqoob | 103 | 2 |
+---------------------+------------+---+
To quickly see the duplicate rows you can run a single simple query
Here I am querying the table and listing all duplicate rows with same user_id, market_place and sku:
select user_id, market_place,sku, count(id)as totals from sku_analytics group by user_id, market_place,sku having count(id)>1;
To delete the duplicate row you have to decide which row you want to delete. Eg the one with lower id (usually older) or maybe some other date information. In my case I just want to delete the lower id since the newer id is latest information.
First double check if the right records will be deleted. Here I am selecting the record among duplicates which will be deleted (by unique id).
select a.user_id, a.market_place,a.sku from sku_analytics a inner join sku_analytics b where a.id< b.id and a.user_id= b.user_id and a.market_place= b.market_place and a.sku = b.sku;
Then I run the delete query to delete the dupes:
delete a from sku_analytics a inner join sku_analytics b where a.id< b.id and a.user_id= b.user_id and a.market_place= b.market_place and a.sku = b.sku;
Backup, Double check, verify, verify backup then execute.
SELECT * FROM bookings
WHERE DATE(created_at) = '2022-01-11'
AND code IN (
SELECT code FROM bookings
GROUP BY code
HAVING COUNT(code) > 1
) ORDER BY id DESC
Would go with something like this:
SELECT t1.firstname t1.lastname t1.address FROM list t1
INNER JOIN list t2
WHERE
t1.id < t2.id AND
t1.address = t2.address;
select address from list where address = any (select address from (select address, count(id) cnt from list group by address having cnt > 1 ) as t1) order by address
the inner sub-query returns rows with duplicate address then
the outer sub-query returns the address column for address with duplicates.
the outer sub-query must return only one column because it used as operand for the operator '= any'
Powerlord answer is indeed the best and I would recommend one more change: use LIMIT to make sure db would not get overloaded:
SELECT firstname, lastname, list.address FROM list
INNER JOIN (SELECT address FROM list
GROUP BY address HAVING count(id) > 1) dup ON list.address = dup.address
LIMIT 10
It is a good habit to use LIMIT if there is no WHERE and when making joins. Start with small value, check how heavy the query is and then increase the limit.