So, I have a table table with three columns I am interested in : value, entity and field_entity.
There are other columns that are not important for this question. There are many different types of entity, and some of them can have the same field_entity, but those two columns determine what the column value refers to (if it is an id number for a person or the address or some other thing)
If I need the name of a person I would do something like this:
select value from table where entity = 'person' and field_entity = 'person_name';
My problem is I need to get a lot of different values (names, last names, address, documents, etc.), so the way I am doing it now is using a left join like this:
select
doc_type.value as doc_type,
doc.value as doc,
status.value as status
from
table doc
-- Get doc type
left join table doc_type
on doc.entity = doc_type.entity
and doc.transaction_id = doc_type.transaction_id
and doc_type.field_entity = 'document_type'
-- Get Status
left join table status
on doc.entity = status.entity
and doc.transaction_id = status.transaction_id
and status.field_entity = 'status'
where doc.entity = 'users' and doc.field_entity = 'document' and doc.transaction_id = 11111;
There are 16 values or more, and this can get a bit bulky and difficult to maintain, so I was wondering if some of you can point out a better way to do this?
Thanks!
I assume that you are not in position to alter the table structure, but can you add views to the database? If so, you can create views based on the different types of entities in your table.
For example:
CREATE VIEW view_person AS
SELECT value AS name
FROM doc
WHERE doc.entity = 'person'
AND doc.field_entity = 'name';
Then you can write clearer queries:
SELECT view_person.name FROM view_person;
Related
I want to query two tables at a time to find the key for an artist given their name. The issue is that my data is coming from disparate sources and there is no definitive standard for the presentation of their names (e.g. Forename Surname vs. Surname, Forename) and so to this end I have a table containing definitive names used throughout the rest of my system along with a separate table of aliases to match the varying styles up to each artist.
This is PostgreSQL but apart from the text type it's pretty standard. Substitute character varying if you prefer:
create table Artists (
id serial primary key,
name text,
-- other stuff not relevant
);
create table Aliases (
artist integer references Artists(id) not null,
name text not null
);
Now I'd like to be able to query both sets of names in a single query to obtain the appropriate id. Any way to do this? e.g.
select id from ??? where name = 'Bloggs, Joe';
I'm not interested in revising my schema's idea of what a "name" is to something more structured, e.g. separate forename and surname, since it's inappropriate for the application. Most of my sources don't structure the data, sometimes one or the other name isn't known, it may be a pseudonym, or sometimes the "artist" may be an entity such as a studio.
I think you want:
select a.id
from artists a
where a.name = 'Bloggs, Joe' or
exists (select 1
from aliases aa
where aa.artist = a.id and
aa.name = 'Bloggs, Joe'
);
Actually, if you just want the id (and not other columns), then you can use:
select a.id
from artists a
where a.name = 'Bloggs, Joe'
union all -- union if there could be duplicates
select aa.artist
from aliases aa
where aa.name = 'Bloggs, Joe';
So I'm trying to update data from a temporary table into a main table.
Let's call these tables temp, and services.
The pseudocode would be something like this...
Sort temp by inserted_on
When service_id and location match in both tables:
If temp.column1 is not null, replace services.column1
If temp.column2 is not null, replace services.column2
etc...
I've got this bit working, although when I have multiple source rows in the temp table that match the condition, not all fields are being updated.
For example, I might have two rows with identical service_id and location, in one row column1 is null and column2 has a value, and in the next row the opposite is true. I need to update these one by one in the order they came in, and overwrite old data if necessary.
I also need to join the temp table inside the UPDATE to retrieve the keys I'm matching on.
I've tried the below code, but it only seems to be updating certain rows, and I can't quite figure out what the logic is behind it.
I'm not worried about the order, I'm just trying to figure out why it's leaving some blanks when there is data ready to fill the gaps.
UPDATE sloc
SET
sloc.ata = COALESCE(tmp.ata, sloc.ata),
sloc.atd = COALESCE(tmp.atd, sloc.atd),
sloc.atp = COALESCE(tmp.atp, sloc.atp),
sloc.eta = COALESCE(tmp.eta, sloc.eta),
sloc.etd = COALESCE(tmp.etd, sloc.etd),
sloc.etp = COALESCE(tmp.etp, sloc.etp),
sloc.plat = COALESCE(tmp.plat, sloc.plat),
sloc.plats_up = COALESCE(tmp.plats_up, sloc.plats_up),
sloc.cis_plats_up = COALESCE(tmp.cis_plats_up, sloc.cis_plats_up)
FROM
services_locations sloc
INNER JOIN services svc ON svc.id = sloc.sid
INNER JOIN ref_tiploc tloc ON tloc.id = sloc.tpl_id
INNER JOIN trainstatus_tmp tmp ON svc.rid = tmp.rid AND tloc.tpl = tmp.tpl
My goal is to create a query, macro or any solution that can do the task described below.
Lets say I have an access 2016 table named "student" with 12 records like this:
And then, lets say I have a second table named "matchme" with 4 records like this:
I need to find a way to
=> first, create a query that returns result of "graduation_date" are equal to Date "1/31/2017" from Table "student" .
=> second, from the result returned from first step, create a query that compare "email" from "student" table with "email" from "matchme" table, and return the [matched] record result.
So the desired result would be:
since the email gary#xxx.com and thomas#xxx.com exist in both tables.
How can I create a query like this?
you can download my access file from here: experiment.accdb
Simple:
select * from student
inner join matchme on student.email = matchme.email
where student.graduation_date = '1/31/2017'
Looking to your data sample you need a join on date and name between the two tables
select * from student
inner join matchme on student.graduation_date = matchme.graduation_date
and student.email = matchme.email
where student.graduation_date = '1/31/2017'
I am trying to update field value from one table to another.
Item with bomRev='A' in Destination table look like show below
Same Item bomRev='A' in source table looks like
I want to update partid field in destination table for bomRev=A by the value in Source filed i want to destination looks exactly like the source.
I tried this but no luck
UPDATE [MIBOMD]
SET [MIBOMD].[partId] = [assy].[partId]
FROM [MIBOMD] INNER JOIN [assy] ON [MIBOMD].[partId] = [assy].[partId]
WHERE bomRev='A' and [bomItem]='600797' AND [MIBOMD].[partId]!=[assy].[partId];
UPDATE m
SET [partId] = a.[partId]
FROM
[MIBOMD] m
INNER JOIN
[assy] a
ON m.[bomItem] = a.[ItemId]
AND m.bomEntry = a.bomEntry
WHERE
m.bomRev='A'
AND m.[bomItem]='600797'
AND m.[partId]!=a.[partId];
You actually were pretty close! Just a couple of key differences. Before I explain I have used Table Aliases in the code I provided it is a shorthand way of referring to the table throughout the query that will make it a little easier to follow and read. To Alias a table after the table name in the from statement simply add a space and an alias or a space " AS " alias.
Now your Join as on partid in your version and that was your main issue. Because you want the records where partid are not the same so you can change the partid of the assy table. Looking at your dataset I was able to determine that the shared key was mibomd.bomItem and assy.ItemId. After clearing that up everything should be good.
Per your comment the only other thing that needed to be added was a second condition on the join to make it unique. [MIBOMD].bomEntry = assy.bomEntry
A little about join conditions. Typically you always want to figure out what the unique relationship between the 2 tables are (bomItem = ItemId and bomEntry = bomEntry) and that is what will go in the ON area of the join. Rarely that will be different and will be for very specific purposes.
Per your comment on how to insert the missing records
INSERT INTO MIBOMD (bomItem, bomRev, bomEntry, lineNbr, dType, partId)
SELECT
bomItem = a.ItemId
,bomRev = 'A' --or change the value to what you want
,a.bomEntry
,lineNbr = ???? --not sure how you are figure this out do if you wan it to be the next line number you can figure that out automatically if you need
,a.partId
FROM
assy a
LEFT JOIN MIBOMD m
ON a.ItemId = m.bomItem
AND a.bomEntry = m.bomEntry
WHERE
m.bomItem IS NULL
This time you would use a left join from assy to mibomd and figure out when they don't match mibomd.bomItem IS NULL
I have a little problem - since im not very experienced in SQL - about joining the same table on multiple values. Imagine there is table 1 (called Strings):
id value
1 value1
2 value2
and then there is table 2 (called Maps):
id name description
1 1 2
so name is reference into the Strings table, as is description. Without the second field referencing the Strings table it would be no problem, id just do an inner join on Strings.id = Maps.name. But now id like to obtain the actual string also for description. What would be the best approach for a SELECT that returns me both? Right now it looks like this:
SELECT Maps.id, Strings.value AS mapName FROM Maps INNER JOIN Strings ON Strings.id = Maps.name;
But that obviously only covers one of the localized names. Thank you in advance.
You can do this with two joins to the same table:
SELECT m.id, sname.value AS mapName, sdesc.value as description
FROM Maps m INNER JOIN
Strings sname
ON sname.id = m.name INNER JOIN
Strings desc
ON sdesc.id = m.description;
Note the use of table aliases to distinguish between the two tables.
As long as you want to get a single value from another table, you can use subqueries to do these lookups:
SELECT id,
(SELECT value FROM Strings WHERE id = Maps.name) AS name,
(SELECT value FROM Strings WHERE id = Maps.description) AS description
FROM Maps