I have table emails_grouping in that I have one column named 'to_ids' this column contains multiple employee Id's . Now I want to change that Id's with respective employee names. employee data is in employee table.
this is in mysql.
I tried multiple ways but I'm not able to replace id's with names because , that 'to_ids' column contains multiple 'Ids'.
description to_ids
'Inactive Employees with missing Last working day', '11041,11109,899,13375,1715,1026'
above is the column which I want to change Id's with employee names.
This problem should demonstrate to you why it's a bad idea to store "lists" of id's like you're doing. You should instead store one id per row.
You can join to your employee table like this:
SELECT e.name
FROM emails_grouping AS g
JOIN employee AS e
ON FIND_IN_SET(e.id, g.to_ids)
WHERE g.description = 'Inactive Employees with missing Last working day';
But be aware that joining using a function like this is not possible to optimize. It will have very slow performance, because it can't look up the respective employee id's using an index. It has to do a table-scan of the employee table, and evaluate the id's against your comma-separated list one by one.
This is just one reason why using comma-separated lists instead of normal columns is trouble. See my answer to Is storing a delimited list in a database column really that bad?
Related
I have 2 MySQL Tables: "parts_revisions" and "categories_revisions". My goal is to use the revisions data in these tables to create a log that lists out all the changes made to parts and categories. Listing the changes to "parts" in one single SQL statement has proven tricky though! Here is the situation:
All entries of each table have "timestamp" columns.
Every parts_revisions entry has a "categoryId" that basically links it to the categories_revisions table. (Every part is a child of a parent category.)
All I want to do is list out all the parts_revisions, but use the human-friendly "name" column from the categories_revisions table based on the categoryId column in parts_revisions. This will make the log more readable.
The trick is that, because there are usually multiple revisions for each category within the categories_revisions table, I cannot do just one big 'ol join on the categoryId column to get the name. The categoryId column is non-unique, and "name"s may vary. What I have to do is get the latest category_revisions entry that has a timestamp that is no later than the timestamp of the part_revisions entry. In other words, we want to get the appropriate category name that was in use AT THE TIME the part revision was made.
Not sure if this matches your table structure, but here's a go at it. It's a bit of an ugly subquery inside a subquery. Guessing it won't be terribly efficient
select part_name,
category,
(select name
from categories_revisions
where categories_revisions.match_id = parts_revisions.category
and categories_revisions.timestamp = (select MAX(categories_revisions.timestamp)
from categories_revisions
where categories_revisions.match_id = parts_revisions.category
and categories_revisions.timestamp < parts_revisions.timestamp)) as name
from parts_revisions;
http://sqlfiddle.com/#!2/da74e/1/0
I am trying to create a table that shows treatment information about patients (though I just wondered if would be better as a query) at a fictional hospital. The idea is that one row of this could be used to print an information sheet for the attending nurse(s).
I would like to make the attending_doctor column contain the name that corresponds with the employee_id.
|Patient_ID|Employee_ID|Attending_Doctor|Condition|Treatment|future_surgery|
Would appreciate any help. Thank you!
Just use a join in your query rather than have the employee name in 2 tables (which would mean updating in more than one location if they change name etc). For the sake of an example, this also gets the patients name from a 3rd table named patients.
eg
SELECT table1.*, employees.name, patients.name
FROM table1
LEFT JOIN employees ON employees.id = table1.employeeId
LEFT JOIN patients ON patients.id = table1.patientsId
Don't use directly this table, but build a view that contains the data you need. Then you can get the data from the view like it was a table.
Basically what you need is to have data in three tables. One table for patients, one table for for employees and one for the reports. Table with reports should contain only the employee_ID. Then you can either build a direct query over these three tables or build a view that will hide the complicated query.
Update 4/25/13 6:25AM: I am using MyISAM
I have searched a lot and am not sure the best way to do this. I have two tables that have matching values in different columns and need to return all that apply to where clause.
Table 1 name agent
Relevant Column Names agent_name and team
Table 2 name poll_data
Relevant Column Names agent and duid
So I want to count how many poll results I get from each teambut I need to somehow add the team from agent table to poll_data by matching the agent.agent_name to poll_data.name so I can return only data for that team. How can I match the records and then search them in a single query.
try this ...
$query1="SELECT COUNT(*) FROM poll_data JOIN agent ON (poll_data.agent = agent.agent_name) GROUP BY agent.team";
you should normalize the database using foreign key.
I have a table with a bunch of orders... one of the columns is order_status. The data in that column ranges from 1 to 5. Each number relates to a name, which is stored in another table that relates that number to the respective name.
SELECT order_id , order_status FROM tablename1
The above would just return the numbers 1,2,3,4,5 for order status. How can i query within the query on the fly to replace these numbers with their respective names.
Also, what's the term used to describe this. I'd Google it if i knew what the appropriate term was.
Each number relates to a name, which is stored in another table that
relates that number to the respective name.
JOIN it with the other table:
SELECT
t.order_id,
s.StatusName
FROM tablename1 AS t
INNER JOIN the statusesTable AS s ON t.order_status = s.status_id;
This has been driving me mad.
I have three tables:
items
ID
name
type
cats
ID
name
items_to_cats
FK_ITEM_ID
FK_CAT_ID
This is a simple many-to-many relationship. I have items and categories. Each item can be linked to one or more categories. This is done via a simple joining table where each row maintains a relationship between one item and one category using foreign key constraints.
You will notice that my "items" table has a field called "type". This is an indexed column that defines the type of content stored there. Example values here are "report", "interview", "opinion", etc.
Here's the question. I want to retrieve a list of categories that have at least one item of type "report".
Ideally I want to get the result in a single query using joins. Help!
select distinct cats.id, cats.name
from cats
join items_to_cats on items_to_cats.fk_cat_id=cats.id
join items on items.id=items_to_cats.fk_item_id
where items.type='report'
Just as a point of database design, if you have a small set of legal values for items.type, i.e. "report", "interview", "opinion", maybe a couple more, then you really should create a separate table for that with, say, an id and a name, then just put the type id in the items table. That way you don't get into trouble because somewhere it's mis-spelled "raport", or even more likely, someone puts "reports" instead of "report".
or how about this :
SELECT c.id, c.name
FROM cats c
WHERE c.id IN
(SELECT ic.fk_cat_id
FROM items_to_cats ic
JOIN items i on i.id=ic.fk_item_id
WHERE items.type='report'
)