select rows where related record doesn't exist - mysql

I need to retrieve rows from a mysql database as follows: I have a contract table, a contract line item table, and another table called udac. I need all contracts which DO NOT have a line item record with criteria based on a relationship between contract line item and udac. If there is a better way to state this question, let me know.
Table Structures
----contract--------------------- ---contractlineitem-----------
| id | customer_id | entry_date | | id | contract_id | udac_id |
--------------------------------- ------------------------------
| 1 | 1234 | 2010-01-01 | | 1 | 1 | 5 |
| 2 | 2345 | 2016-01-31 | | 2 | 1 | 2 |
--------------------------------- | 3 | 1 | 1 |
| 4 | 2 | 4 |
| 5 | 2 | 2 |
------------------------------
---udac----------
| id | udaccode |
-----------------
| 1 | SWBL/R |
| 2 | SWBL |
| 3 | ABL/R |
| 4 | ABL |
| 5 | XRS/F |
-----------------
Given the above data, contract 2 would show up but contract 1 would not, because it has contractlineitems that point to udacs that end in /F or /R.
Here's what i have so far, but it's not correct.
SELECT c.*
FROM contract c
JOIN contractlineitem cli
ON c.id = cli.contract_id
WHERE c.entry_timestamp > '2016-01-01 00:00:00'
AND NOT EXISTS (
SELECT cli.id
FROM contractlineitem cli_i
JOIN udac u
ON cli_i.udac_id = u.id
WHERE u.udaccode LIKE '%/F' OR u.udaccode LIKE '%/R'
AND cli_i.contract_id = cli.contract_id);

Tom's comment that your WHERE clause is wrong may be the problem you are chasing. Plus, using a correlated subquery may be problematic for performance if the optimizer can't figure out a better way to do it.
Here is the better way to do it using an OUTER JOIN:
SELECT c.*
FROM contract c
JOIN contractlineitem cli
ON c.id = cli.contract_id
LEFT OUTER JOIN udac u
ON ( u.id = cli.udac_id
AND ( u.udaccode LIKE '%/F' OR u.udaccode LIKE '%/R' ) )
WHERE c.entry_timestamp > '2016-01-01 00:00:00'
AND u.id IS NULL
Try that out and see if it does what you want. The query essentially does what you stated: It tries to join to udac where the code ends in '/F' or '/R', but then it only accepts the ones where it can't find a match (u.id IS NULL).
If the same row is returned multiple times incorrectly, throw a distinct on the front.

Related

Combining three SQL queries into one

I got working code from three queries but I would like to combine them into one or two. Basically I am checking if a provided phone number exists in table contacts or leads as well as if it exists as a secondary number in customfieldsvalues (not all leads have a customfield value though). I am using a CRM system based on CodeIgniter.
What I want to do (non-correct/hypothetical query):
SELECT * FROM contacts OR leads WHERE phonenumber = replace(X, '-', '')
OR leads.id = customvaluefields.relid AND cfields.fieldid = 41 AND cfields.value = X
Tables
table : contacts
+-------+----------------+----------------+
| id | firstname | phonenumber |
+-------+----------------+----------------+
| 1 | John | 214-444-1234 |
| 2 | Mary | 555-111-1234 |
+-------+----------------+----------------+
table : leads
+-------+-----------+---------------------+
| id | name | phonenumber |
+-------+-----------+---------------------+
| 1 | John | 214-444-1234 |
| 2 | Mary | 555-111-1234 |
+-------+-----------+---------------------+
table : customvaluefields
+-------+-----------+-------------+-----------+
| id | relid | fieldid | value |
+-------+-----------+-------------+-----------+
| 1 | 1 | 41 | 222333444 |
| 2 | 1 | 20 | Management|
| 3 | 2 | 41 | 333444555 |
+-------+-----------+-------------+-----------+
If I understand what you are trying to, maybe UNION ALL would work. This is something to get you started:
SELECT C.ID, C.FirstName, C.Phonenumber
FROM Contacts C
JOIN CustomValueField CVF
ON c.ID = CVF.RelID AND
CVF.ID = 41
AND REPLACE(Phonenumber,'-','') = cvf.Value
UNION ALL
SELECT L.ID, L.FirstName, L.Phonenumber
FROM Leads L
JOIN CustomValueField CVF
ON L.ID = CVF.RelID AND
CVF.ID = 41
AND REPLACE(Phonenumber,'-','') = cvf.Value
I'm joining the contacts and leads tables to CustomeValueField in each query and then UNION them together along with the WHERE clause in each. I'm sure it's not 100% correct for what you need, but should get you headed to a solution. Here is more information: https://dev.mysql.com/doc/refman/8.0/en/union.html

joining multiple tables and returning a zero if not row in one

I'm trying to setup a new permissions database in MySQL and I'm breaking my brain over something that I'm sure is very simple. I'm certain something to this tune has been answered here before but after hours of searching I have found nothing that works.
I have 4 tables that are relevant
Permission (contains every possible permission)
|permission_name | description |
--------------------------------
|users.list | etc. etc. |
|users.update | etc. etc. |
|users.delete | etc. etc. |
User
| id | fname | group_id |
------------------------------
| 1 | John | 1 |
| 2 | Nancy | 1 |
| 3 | Paul | 2 |
Group
| group_id | group_name |
-------------------------
| 1 | Webmasters |
| 2 | Corporate |
| 3 | HR |
Group_permission (contains permissions relevant to each group)
| group_id | permission_name | permission_type (1=Y|0=not set|-1=N)
----------------------------------------------
| 1 | users.list | 1 |
| 1 | users.update | 1 |
| 2 | users.list | 1 |
OK so lots of relations going on, but I'm trying to get ALL the group permissions for a specific user EVEN if the group permission doesn't exist yet.
I imagined this being some sort of left join using a permission table as a base, but whenever I include the WHERE user.id = 2 it limits my result set down and won't include nulls on the right side.
SELECT a.permission_name, IFNULL(b.permission_type, 0)
FROM permission a
LEFT JOIN group_permission b on b.permission_name = a.permission_name
LEFT JOIN user c on c.group_id = b.group_id
WHERE c.id = 2
the result I want to see for Nancy is
|permission_name | permission_type |
------------------------------------
|users.list | 1 |
|users.update | 0 |
|users.delete | 0 |
I won't know what group the user is in on the PHP side, so I have to query by using the users ID only.
All I'm getting is
|permission_name | permission_type |
------------------------------------
|users.list | 1 |
Any help appreciated. TIA
It ended up being just a subquery that did the trick.
SELECT a.permission_name, IFNULL(b.permission_type, 0)
FROM permission a
NATURAL LEFT JOIN
(
SELECT a.group_id, a.permission_name, a.permission_type FROM group_permission a
NATURAL LEFT JOIN users b
WHERE b.id = 2
) as b
Not 100% sure that this will work, but try joining the group_permissions table to the permissions table.
SELECT a.permission_name, IFNULL(b.permission_type, 0)
FROM group_permission a
LEFT JOIN permission b on a.permission_name = b.permission_name
LEFT JOIN user c on c.group_id = b.group_id
WHERE c.id = 2

How can I merge rows from two joined tables?

There are two tables, which can be joined, and the relationship is 1 to many. I wish the rows of results to be merged.
For example:
Table 1: contacts
.------------.----------.
| contact_id | username |
:------------+----------:
| 1 | user1 |
:------------+----------:
| 2 | user2 |
:------------+----------:
| 3 | user3 |
'------------'----------'
Table 2: documents
.-------------.------------.----------.
| document_id | contact_id | filename |
:-------------+------------+----------:
| 1 | 1 | abc.txt |
:-------------+------------+----------:
| 2 | 1 | bcd.txt |
:-------------+------------+----------:
| 3 | 1 | cde.txt |
:-------------+------------+----------:
| 4 | 2 | 123,txt |
:-------------+------------+----------:
| 5 | 2 | 234.txt |
:-------------+------------+----------:
| 6 | 3 | xyz.txt |
'-------------'------------'----------'
The result I wish I can get:
.------------.----------.---------------------------.
| contact_id | username | filenames |
:------------+----------+---------------------------:
| 1 | user1 | abc.txt, bcd.txt, cde.txt |
:------------+----------+---------------------------:
| 2 | user2 | 123.txt, 234.txt |
:------------+----------+---------------------------:
| 3 | user3 | xyz.txt |
'------------'----------'---------------------------'
Updated:
SELECT c.contact_id, c.username, GROUP_CONCAT(d.filename) as filenames
FROM contacts c
LEFT JOIN documents d
ON c.contact_id = d.contact_id
GROUP BY c.contact_id
You should really post your attempts with your question, so that we can see what you have tried. In that way, it will be easy to push you in the right direction, as well as give the rest of us the impression that you have put some effort into the matter before asking the question. Stackoverflow is not a coding service.
To answer your question,
What you would like to do in this case, is to perform an INNER JOIN on your two tables, and have the MYSQL function, GROUP_CONCAT();, in your SELECT statement.
When you look at your two tables, you have a coherent id (contact_id) that you should use in your INNER JOIN to link your two tables together.
You then, at the end, need to perform a GROUP BY to group your results accordingly, i.e. to group the results by contact_id.
Your SQL would look something like this:
SELECT
tbl_contacts.contact_id,
tbl_contacts.username,
GROUP_CONCAT(tbl_documents.filename) as file_name
FROM
tbl_contacts
INNER JOIN
tbl_documents ON tbl_contacts.contact_id = tbl_documents.contact_id
GROUP BY
tbl_contacts.contact_id
Working SQL fiddle

Select the most current records from multiple identical rows in the MySQL database

I am working on a product sample inventory system where I track the movement of the products. The status of each product can have a status of "IN" or "OUT" or "REMOVED". Each row of the table represents a new entry, where ID, status and date are unique. Each product also has a serial number.
I need help with a SQL query that will return all products that are currently "OUT". If I simply just select SELECT * FROM table WHERE status = "IN", it will return all products that ever had status IN.
Every time product comes in and out, I duplicate the last row of that specific product and change the status and update the date and it will get a new ID automatically.
Here is the table that I have:
id | serial_number | product | color | date | status
------------------------------------------------------------
1 | K0T4N | XYZ | silver | 2016-07-01 | IN
2 | X56Z7 | ABC | silver | 2016-07-01 | IN
3 | 96T4F | PQR | silver | 2016-07-01 | IN
4 | K0T4N | XYZ | silver | 2016-07-02 | OUT
5 | 96T4F | PQR | silver | 2016-07-03 | OUT
6 | F0P22 | DEF | silver | 2016-07-04 | OUT
7 | X56Z7 | ABC | silver | 2016-07-05 | OUT
8 | F0P22 | DEF | silver | 2016-07-06 | IN
9 | K0T4N | XYZ | silver | 2016-07-07 | IN
10 | X56Z7 | ABC | silver | 2016-07-08 | IN
11 | X56Z7 | ABC | silver | 2016-07-09 | REMOVED
12 | K0T4N | XYZ | silver | 2016-07-10 | OUT
13 | 96T4F | PQR | silver | 2016-07-11 | IN
14 | F0P22 | DEF | silver | 2016-07-12 | OUT
This query will give you all the latest records for each serial_number
SELECT a.* FROM your_table a
LEFT JOIN your_table b ON a.serial_number = b.serial_number AND a.id < b.id
WHERE b.serial_number IS NULL
Below query will give your expected result
SELECT a.* FROM your_table a
LEFT JOIN your_table b ON a.serial_number = b.serial_number AND a.id < b.id
WHERE b.serial_number IS NULL AND a.status LIKE 'OUT'
There are two good ways to do this. Which way is best,in terms of performance, can depend on various factors, so try both.
SELECT
t1.*
FROM table t
LEFT OUTER JOIN table later_t
ON later_t.serial_number = t.serial_number
AND later_t.date > t.date
WHERE later_t.id IS NULL
AND t.status = "OUT"
Which column you check from later_t for IS NULL does not matter, so long as that column is declared NOT NULL in the table definition.
The other logically equivalent method is:
SELECT
t.*
FROM table t
INNER JOIN (
SELECT
serial_number,
MAX(date) AS date
FROM table
GROUP BY serial_number
) latest_t
ON later_t.serial_number = t.serial_number
AND latest_t.date = t.date
WHERE t.status = "OUT"
For each of these queries, I strongly suggest the following index:
ALTER TABLE table
ADD INDEX `LatestSerialStatus` (serial_number,date)
I use this type of query a lot in my own work, and have the above index as the primary key on tables. Query performance is extremely fast in such cases, for these type of queries.
See also the documentation on this query type.

How to join tables with SQL query and take number of tied columns?

I'm having BookTable in database (with foregin hey LibID):
| BookID | BookName | BookPrice | LibID |
-------------------------------------------
| 1 | Book_1 | 200 | 1 |
| 2 | Book_2 | 100 | 1 |
| 3 | Book_3 | 300 | 2 |
| 4 | Book_4 | 150 | 4 |
and also LibraryTable:
| LibID | LibName | LibLocation |
-----------------------------------
| 1 | Lib_1 | Loc_1 |
| 2 | Lib_2 | Loc_2 |
| 3 | Lib_3 | Loc_3 |
| 4 | Lib_4 | Loc_4 |
I need to write SQL query that will return be the info about the library and number of books for that library:
| LibID | LibName | NumberOfBooks|
------------------------------------
| 1 | Lib_1 | 2 |
| 2 | Lib_2 | 1 |
| 3 | Lib_3 | 0 |
| 4 | Lib_4 | 1 |
It should be one SQL query, probably with nested queries or joins.. Not sure how the query should look like:
SELECT L.LibID AS LibID, L.LibName AS LibName, COUNT(B) AS NumberOfBooks
FROM LibraryTable L, BookTable B
WHERE L.LibID = B.LibID
Will that work?
No, this query will not work. COUNT aggregates data, so you must explicitely tell the DBMS for which group of data you want the count. In your case this is the library (you want one result record per library).
COUNT's parameter is a column, not a table, so change this to * (i.e. count records) or a certain column (e.g. LibID).
The join syntax you are using is valid, but deprecated. Use explicit joins instead. In your case an outer join would even show libraries that have no books at all, if such is possible.
select l.libid, l.libname, count(b.libid) as numberofbooks
from librarytable l
left outer join booktable b on b.libid = l.libid
group by l.libid;
You could also do all this without a join at all and get the book count in a subquery instead. Then you wouldn't have to aggregate. That's way simpler and more readable in my opinion.
select
l.libid,
l.libname,
(select count(*) booktable b where b.libid = l.libid) as numberofbooks
from librarytable l;
SELECT lt.LibID AS LibID, lt.LibName AS LibName, count(*) AS NumberOfBooks
FROM BookTable AS bt
LEFT JOIN LibraryTable AS lt ON bt.LibID = lt.LibID
GROUP BY bt.LibID