I have a table joined from two other tables. I would like this table to stay updated with entries in the other two tables.
First Table is "employees"
I am using the ID, Last_Name, and First_Name.
And the second Table is "EmployeeTimeCardActions"
using columns ID, ActionTime, ActionDate, ShiftStart, and ActionType.
ID is my common column that the join was created by..Joined Table...
Because I usually have a comment saying I did not include enough information, I do not need a exact specific code sample and I think I have included everything needed. If there is a good reason to include more I will, I just try to keep as little company information public as possible
Sounds like you're having your data duplicated across tables. Not a smart idea at all. You can update data in one table when a row is updated in a different one via triggers but this is a TERRIBLE approach. If you want to display data joined from 2 tables, the right approach here is using an SQL VIEW which will display the current data.
Related
I created 2 summary tables form the same source data for different date ranges.
Now that I have these multiple summary tables, I want to put those tables together
so that I will be able to run a summary on the combined table.
It's creating the summary table that is presenting the problem.
scratch.table_1 has 809,598 records.
scratch.table_2 has 1,228,176 records.
They both have the same set of fields from the source table,
plus a "record_number" field I created on each table using count(1).
The code I used to put these two tables together was:
create table scratch.table_1_and_2
select * from scratch.table_1
union all
select * from scratch.table_2
I assumed that there would be 809,598 + 1,228,176 records in the new table (2,037,774 records).
But there are only 1,960,769 records in the new table.
What am i doing wrong?
One way to troubleshoot would be to identify some of the missing records and see what might be different about the data in those that would cause them to be left out. A UNION ALL should include duplicate records so duplicates shouldn't be the issue. Maybe there is some data issue that's causing those records to be dropped. Also I'm assuming there isn't any funny business with Views going on in the underlying tables and that no data loads are affecting your record counts.
SELECT DISTINCT
...
...
...
FROM Reviews Rev
INNER JOIN Reviews SubRev ON Subrev.W_ID=Rev.ID
WHERE Rev.Status='Approved'
This is a small part of a long query that I've been trying to understand for a day now. What is happening with the join? Reviews table appears to be joined with itself, under different aliases. Why is this done? What does it achieve? Also, ID field of the Reviews table is null for the entries that are nevertheless selected and returned. This is correct, but I don't understand how that can happen if the W_ID field is not null.
It allows you to join one row from the table to a different row in the table.
I've both seen this done, and used it myself, in cases where you maybe have a relationship between those rows.
Real-world examples:
An old version of a record and a newer version
Some sort of hierarchical relationship (e.g. if the table contains records of people, you can record that someone is a parent of someone else). There are probably plenty of other possible use cases, too.
SQL allows you to create a foreign key which relates between two different columns in the same table.
I have the following problem.
I have a table Entries that contains 2 columns:
EntryID - unique identifier
Name - some name
I have another EntriesMapping table (many to many mapping table) that contains 2 columns :
EntryID that refers to the EntryID of the Entries table
PartID that refers to a PartID in a seprate Parts table.
I need to write a SP that will return all data from Entries table, but for each row in the Entries table I want to provide a list of all PartID's that are registered in the EntriesMapping table.
My question is how do I best approach the deisgn of the solution to this, given that the results of the SP would regularly be processed by an app so performance is quite important.
1.
Do I write a SP that will select multiple rows per entry - where if there are more than one PartID's registered for a given entry - I will return multiple rows each having the same EntryID and Name but different PartID's
OR
2.
Do I write a SP that will select 1 row per entry in the Entries table, and have a field that is a string/xml/json that contains all the different PartID's.
OR
3. There is some other solution that I am not thinking of?
Solution 1 seems to me to be the better way to go, but I will be passing lots of repeating data.
Solution 2 wont pass extra data, but the string/json/xml would need to be processed additionally, resuling in larger cpu time per item.
PS: I feel like this is quite a common problem to solve, but I was unable to find any resource that can provide common solutions or some pros/cons to different approaches.
I think you need simple JOIN:
SELECT e.EntryId, e.Name, em.PartId
FROM Entries e
JOIN EntriesMapping em ON e.EntryId = em.EntryId
This will return what you want, no need for stored procedure for that.
I have two tables. One gives me basic information about demographics. One of the categories in my demographics table is a subset of people, which is housed in ATID 530 (there are several hundred different ATIDs) of this table:
As you can see the PK of this table is ADefID. My other table uses this as a FK. It houses indexes to additional definitions for records in the original table. However those additional definitions are also just records in the original table. The second table just provides pointers.
So if we pick a record, let's say ADefID=4684423, and look it up in the second table, we are returned this:
The CategoryADefID will then point back to the original table's ADefID for another record:
(note the ATID of this ADefID differs from the original ADefID that this is related to)
So. Let's say I want to pull out a set of records from the first row, say
WHERE ATID = 530 AND CycleID = 9600
But I also want to pull the ADesc (and maybe ADEValue) from the related definition as a separate field.
So the end result would look sort of like this:
I understand enough to make the join to the second table and return the CategoryADefID, but I dont know how to use that to call back to another ADefID in the original table. The other limitation is that I would use the ATID field in the WHERE clause (ATID=530) and the related definition will have a different ATID.
Just add another join back to the original table:
Select *
From tableA a
join tableB b on b.ADefID=a.ADefID
join tableA a2 on a2.ADefID = b.CategoryADefID
Where a.ADefID = 4684423
I have two table Employee and Salary table, salary consists Salary of employee in a field named Salary_employee.
Second one is Extra Expense, Extra expense consists records related to extra expenses of a company like electricity bills,office maintenance in a field named extra_expense.
(Their is no relationship between these two table).
Finally, I just wanted to show all the expenses of company in a report, for this i need to group both the table. what to use here join or union ??.
If there is no relationship between the two tables, then this really cannot work since you dont know where the expense is supposed to tie into. You should redesign the database if possible as this sounds impossible based on your description.
UPDATE
OK, by the look of your screenshots, I am guessing that this database only stores one companies info? And not multiple?
IF that is correct, AND if all you want to do is squish the data together into one flowing report of expenses, then I would indeed suggest a UNION. A JOIN would not give you the flow you are looking for. A UNION will just smash the two outputs together into one...which I think is what you are asking for?
SELECT ext_amount AS amount, ext_date AS date_of_trans
FROM extra_expenses
UNION
SELECT sal_cash AS amount, sal_dateof_payment AS date_of_trans
FROM employee_salary
It sounds like you don't need to use group or join. Simply query both tables separately within a script and handle them both accordingly to their structure to produce a report.
Join and union are functions which you can use to extract different information on a common thing from separate tables. E.g. if you have a user whose private details are stored in one table, but their profile information is in another table. If you want to display both private details as well as profile info, you can join the two tables by the common user name in order to combine and gather all info on the user in one query.