I have a database with several tables, one being used to reference others :
Main table :
MAIN | table1 | table2 | table3
int | int | int
Each line of this table corresponds to a product, and contains the oid of a line in a daughter table
Then I have my daughter tables :
TABLE1 | name | adress | phone
| text | text | ...
My question is quite simple, even though as I just start using databases I can't get to find the answer.
I would like to get the oid(s) of the line(s) of the main table which references the line of table1 for which name is equals to "bob".
Something like :
SELECT * from main where table1.name = "bob"
If no complete solution, could you point me to some documentation ?
I think I miss vocabulary to find proper ressurces to do that.
Thanks by advance
assuming the oid is a column in table 1 as well as in the main table:
SELECT m.oid
FROM main m
INNER JOIN table1 t
ON m.table1 = t.oid
WHERE t.name = 'bob'
You mean like SELECT oid FROM MAIN WHERE table1 IN (SELECT oid FROM TABLE1 WHERE name = 'bob')?
table1 == foreign key from MAIN to TABLE1.
Related
Please who can help with this scenario?
I have two tables, both they have a common column ID, and Table 1 has a column Title. Normally I should update the content of this Title column for some ID, but since the table was already in use somewhere else, it wasn't a good idea to change data directly in Table 1.
That's why I created a new table table 2, which hold only the Title that must be changed associated with these ID that must be changed.
Now I am trying to get these updated titles from table 2, when there is a matching ID in table 1, otherwise show only the contents of table 1.
The result should be something like that but without using If statements.
__ID__ Title
| | | |
| | | |
You can use LEFT OUTER JOIN to this new table and COALESCE() function to say "If there is data in the new table, use it, otherwise use the data in the existing table" . Something like:
SELECT t1.id, COALESCE(t2.title, t1.title) as title
FROM t1
LEFT OUTER JOIN t2 ON t1.id = t2.id;
I have Problem statement in Apache Phoenix in which I need to combine three tables for the result.
I have three views over Hbase table, Schema is as follow
Table group:-
pk | Title | ownerId | data
Table Members:-
pk | parentId | Email | data
Table userinfo:-
pk | Email | First Name | Last Name
Now, I want to fetch groups whose title matches with input string if not matched then want to fetch groups whose members have a name that matches with the input string.
I already tried query as follow:-
select * from Group where pk like 'Prefix_%'
and (TITLE like '%A%'
or (OWNER_ID in
(
select parentId from MEMBERS where EMAIL in
( select distinct(EMAIL) from USER_INFO
where pk like 'PREFIX%' and
( FIRST_NAME like '%A%' or LAST_NAME like '%A%')
)
)
) ) order by TITLE limit 5;
But, it's taking too much time also tried Left Join Query with similar but not give expected result.
Please Suggest how can I improve this?
I have a sparse table structured like:
id | name | phone | account
There is no primary key or index
There are also null values. What I want is to "glue" data from different rows together, e.g.:
Given
id | name | phone | account
1 null '339-33-27' 4
null 'John' '339-33-27' 4
I want to end up with
id | name | phone | account |
1 'John' '339-33-27' 4
However, I don't know which values are missed in the table.
What are the general way to approach this kind of problem? Do I need to use only joins or might be recursive functions?
Update: Provided more clear example
id to account is many-to-many
account to name is many-to-many
phone to name is one-to-one
The database is basically raw transactional data
What I want to is to get all the rows for which I already have / could find an account
If I understand you correctly then this might work. What you need is a self join
select t2.id, t1.name, t1.phone, t1.account
from table1 t1
join table1 t2 on t1.account = t2.account and t1.phone = t2.phone
where t1.name is not null
However this particular query relies on an assumption from your example data. My assumption is that if name is not null, Id will be null and the Id can be found by looking at the phone number and account. If this assumption is not true , then we may need more sample data to solve your problem.
Depending on the data, you might need left joins or to swap so that T1 gets the id and not the name and the where condition is that ID is not null. It's hard to tell with such a small data sample size.
I want to move data from these old tables
restaurant_id | restaurant_nm | more data
bar_id | bar_nm | more data
To
venue_id | venue_nm
I'll add field venue_id to the old tables
Then I want to run a query similar to this:
INSERT INTO `venue` (SELECT null, `restaurant_nm` FROM `restaurant`)
However, while do the copy I want the new id to be stored into the old table. Is this possible with pure mysql?
Edit The old restaurants can be chains (multiple messy joe's), the only thing that identifies them 100% is the id
You could temporarily store the old ID in the new table (in an extra column) and then do an UPDATE on the old table. That's two lines of 'pure SQL.'
restaurant_id |restaurant_name | v_id
venue_id | venue_name | rest_id
INSERT INTO `venue` (SELECT null, `restaurant_nm`, `restaurant_id` FROM `restaurant`)
and then
UPDATE restaurant r
INNER JOIN venue v
ON r.restaurant_id = v.rest_id
SET r.v_id = v.venue_id
Interested to see what a more elegant solution might be.
This is somewhat related to this question:
I have a table with a primary key, and I have several tables that reference that primary key (using foreign keys). I need to remove rows from that table, where the primary key isn't being referenced in any of those other tables (as well as a few other constraints).
For example:
Group
groupid | groupname
1 | 'group 1'
2 | 'group 3'
3 | 'group 2'
... | '...'
Table1
tableid | groupid | data
1 | 3 | ...
... | ... | ...
Table2
tableid | groupid | data
1 | 2 | ...
... | ... | ...
and so on. Some of the rows in Group aren't referenced in any of the tables, and I need to remove those rows. In addition to this, I need to know how to find all of the tables/rows that reference a given row in Group.
I know that I can just query every table and check the groupid's, but since they are foreign keys, I imagine that there is a better way of doing it.
This is using Postgresql 8.3 by the way.
DELETE
FROM group g
WHERE NOT EXISTS
(
SELECT NULL
FROM table1 t1
WHERE t1.groupid = g.groupid
UNION ALL
SELECT NULL
FROM table1 t2
WHERE t2.groupid = g.groupid
UNION ALL
…
)
At the heart of it, SQL servers don't maintain 2-way info for constraints, so your only option is to do what the server would do internally if you were to delete the row: check every other table.
If (and be damn sure first) your constraints are simple checks and don't carry any "on delete cascade" type statements, you can attempt to delete everything from your group table. Any row that does delete would thus have nothing reference it. Otherwise, you're stuck with Quassnoi's answer.