Sorry, I'm very new to SQL. I just learned it few hours ago. I'm using MariaDB + InnoDB Engine with HeidiSQL software + CodeIgniter 3. Let's say I have a table named disciples with the following data:
-------------------
| sort_id | name |
-------------------
| 1 | Peter |
| 4 | John |
| 3 | David |
| 5 | Petrus |
| 2 | Matthew |
-------------------
I'm fully aware that it's better to have a column called sort_id to be able to fetch the data using ORDER BY if I prefer a custom sorting. But if I delete row 3, the new table will look like this:
-------------------
| sort_id | name |
-------------------
| 1 | Peter |
| 4 | John |
| 5 | Petrus |
| 2 | Matthew |
-------------------
The thing is I'm having OCD (imagine there are 1000 rows), it hurts my eyes to see this mess with some missing numbers (in this case number 3 - see the above table) under sort_id. I think it has something to do with "relational database". Is there a way to quickly and automatically "re-assign/reset" new sort_id numbers to given rows and sort them ASC order according to the name using SQL code without having to do it manually?
-------------------
| sort_id | name |
-------------------
| 1 | John |
| 2 | Matthew |
| 3 | Peter |
| 4 | Petrus |
-------------------
I figured this out after reading the answer from Lynn Crumbling.
She made me realized I need a primary key in order to have a better management for my rows which is exactly what I was looking for. It happens that InnoDB automatically creates a primary key and is hidden from HeidiSQL interface unless I specify a specific column for example id. Now, I can re-organize my table rows by editing the primary key id and the table row will automatically sort itself the way I want. Before this, I edited the sort_id but the data did not update accordingly because it was not the primary key.
------------------------
| id | sort_id | name |
------------------------
| 1 | 1 | Peter |
| 2 | 4 | John |
| 3 | 5 | Petrus |
| 4 | 2 | Matthew |
------------------------
Thank you.
Related
I'm working on my senior High School Project and am reaching out to the community for help! (As my teacher doesn't know the answer to my question).
I have a simple "Products" table as shown below:
I also have a "Orders" table shown below:
Is there a way I can create a field in the "Orders" table named "Total Cost", and make that automaticly calculate the total cost from all the products selected?
Firstly, I would advise against storing calculated values, and would also strongly advise against using calculated fields in tables. In general, calculations should be performed by queries.
I would also strongly advise against the use of multivalued fields, as your images appear to show.
In general, when following the rules of database normalisation, most sales databases are structured in a very similar manner, containing with the following main tables (amongst others):
Products (aka Stock Items)
Customers
Order Header
Order Line (aka Order Detail)
A good example for you to learn from would be the classic Northwind sample database provided free of charge as a template for MS Access.
With the above structure, observe that each table serves a purpose with each record storing information pertaining to a single entity (whether it be a single product, single customer, single order, or single order line).
For example, you might have something like:
Products
Primary Key: Prd_ID
+--------+-----------+-----------+
| Prd_ID | Prd_Desc | Prd_Price |
+--------+-----------+-----------+
| 1 | Americano | $8.00 |
| 2 | Mocha | $6.00 |
| 3 | Latte | $5.00 |
+--------+-----------+-----------+
Customers
Primary Key: Cus_ID
+--------+--------------+
| Cus_ID | Cus_Name |
+--------+--------------+
| 1 | Joe Bloggs |
| 2 | Robert Smith |
| 3 | Lee Mac |
+--------+--------------+
Order Header
Primary Key: Ord_ID
Foreign Keys: Ord_Cust
+--------+----------+------------+
| Ord_ID | Ord_Cust | Ord_Date |
+--------+----------+------------+
| 1 | 1 | 2020-02-16 |
| 2 | 1 | 2020-01-15 |
| 3 | 2 | 2020-02-15 |
+--------+----------+------------+
Order Line
Primary Key: Orl_Order + Orl_Line
Foreign Keys: Orl_Order, Orl_Prod
+-----------+----------+----------+---------+
| Orl_Order | Orl_Line | Orl_Prod | Orl_Qty |
+-----------+----------+----------+---------+
| 1 | 1 | 1 | 2 |
| 1 | 2 | 3 | 1 |
| 2 | 1 | 2 | 1 |
| 3 | 1 | 1 | 4 |
| 3 | 2 | 3 | 2 |
+-----------+----------+----------+---------+
You might also opt to store the product description & price on the order line records, so that these are retained at the point of sale, as the information in the Products table is likely to change over time.
My first post here. Here's what i'm trying to do and i'm simplifying for this question. I have 2 tables.
Companies
--------------------------------
| COMPANY_ID | NAME |
--------------------------------
| 1 | Google |
| 2 | Santas Factory|
| 3 | Pied Piper |
--------------------------------
Employees
------------------------------------------------------
| EMPLOYEE_ID | COMPANY_ID | NAME |
------------------------------------------------------
| 1 | 1 | Larry Page |
| 2 | 1 | Sergey Brin |
| 3 | 2 | Santa Claus |
------------------------------------------------------
I have a PLSQL that will insert with type objects. My question is if i have an type object of the same company what is the best practice in possibly updating, deleting or inserting to the child table?
Example payload:
Company_id: 1
Name: Google
Employees:
|__ Name: Larry Single Page
|__ Name: Sundar Pichai
How should I,
update larry Page
delete sergey brin (sorry sergey)
insert sundar pichai
or is it even possible?
Thanks,
Allen
I am new to working with databases and I want to make sure I understand the best way to add or remove data from a database without making a mess of any related data.
Here is a scenario I am working with:
I have a Tags table, with an Identity ID column. The Tags can be selected via the web application to categorize stories that are submitted by a user. When the database was first seeded; like tags were seeded in order together. As you can see all the Campuses (cities) were 1-4, the Colleges (subjects) are 5-7, and Populations are 8-11.
If this database is live in production and the client wants to add a new Campus (City) tag, what is the best way to do this?
All the other city tags are sort of organized at the top, it seems like the only option is to insert any new tags at to bottom of the table, where they will end up taking whatever the next ID available is. I suppose this is fine because the Display category column will allow us to know which categories these new tags actually belong to.
Is this typical? Is there better ways to set up the database or handle this situation such that everything remains more organized?
Thank you
+----+------------------+---------------+-----------------+--------------+--------+----------+
| ID | DisplayName | DisplayDetail | DisplayCategory | DisplayOrder | Active | ParentID |
+----+------------------+---------------+-----------------+--------------+--------+----------+
| 1 | Albany | NULL | 1 | 0 | 1 | NULL |
| 2 | Buffalo | NULL | 1 | 1 | 1 | NULL |
| 3 | New York City | NULL | 1 | 2 | 1 | NULL |
| 4 | Syracuse | NULL | 1 | 3 | 1 | NULL |
| 5 | Business | NULL | 2 | 0 | 1 | NULL |
| 6 | Dentistry | NULL | 2 | 1 | 1 | NULL |
| 7 | Law | NULL | 2 | 2 | 1 | NULL |
| 8 | Student-Athletes | NULL | 3 | 0 | 1 | NULL |
| 9 | Alumni | NULL | 3 | 1 | 1 | NULL |
| 10 | Faculty | NULL | 3 | 2 | 1 | NULL |
| 11 | Staff | NULL | 3 | 3 | 1 | NULL |
+----+------------------+---------------+-----------------+--------------+--------+----------+
The terms "top" and "bottom" which you use aren't really applicable. "Albany" isn't at the "Top" of the table - it's merely at the top of the specific view you see when you query the table without specifying a meaningful sort order. It defaults to a sort order based on the Id or an internal ROWID parameter, which isn't the logical way to show this data.
Data in the table isn't inherently ordered. If you want to view your tags organized by their category, simply order your query by DisplayCategory (and probably by DisplayOrder afterwards), and you'll see your data properly organized. You can even create a persistent View that sorts it that way for your convenience.
First, I'm sorry for the ambiguous title.
Here's my problem :
I'm using Access and I have this table :
+--------+-----------+
| PARENT | CHILD |
+--------+-----------+
| JOHN | TANIA |
| JOHN | ROBERT |
| JOHN | APRIL |
| HELEN | TOM |
| HELEN | GABRIELLE |
+--------+-----------+
And I would like to add a column like this with queries or VBA code :
+--------+-----------+---------+
| PARENT | CHILD | LIST |
+--------+-----------+---------+
| JOHN | TANIA | CHILD 1 |
| JOHN | ROBERT | CHILD 2 |
| JOHN | APRIL | CHILD 3 |
| HELEN | TOM | CHILD 1 |
| HELEN | GABRIELLE | CHILD 2 |
+--------+-----------+---------+
I want to do this because at the end, I want to run a cross tab query. I'm only missing that last column to create that query.
I tried to do it in a recordset, but my database starts bloating after a couple of rst.Update (I have 700k+ rows)
I created a temporary table and used UPDATE queries but it just takes too much time.
I think there might be a SQL code that would do what I need, but I just can't figure it out. I hope you could help me, thanks :)
You can do something like the below, but it would be much better with some sort of IDs:
SELECT Parent.PARENT,
Parent.CHILD,
(SELECT Count(*)
FROM Parent p
WHERE p.Parent=Parent.Parent
AND p.Child<=Parent.Child) AS ChildNo
FROM Parent
ORDER BY Parent.PARENT, Parent.CHILD;
Parent is the name of the table.
I have a table with information like this.
ID | Name | #ofCow | UItem | place
--------+---------+-------- +---------+----------
0 | Bob | 7 | 1 | maine
1 | Bob | 3 | 5 | new york
2 | Tom | 2 | 5 | cali
I wish to produce a table like this where it would add up the number of cows and Uitem if the name is the same. However my select query seems to not be working. I suspect it is because the place column is the problem. Since you can't add 'Maine' and 'New York' together. Can anyone help me find a solution ?
ID | Name | #ofCow | UItem |
--------+---------+-------- +---------+
0 | Bob | 10 | 6 |
2 | Tom | 2 | 5 |
TLDR : Add the values in two columns in table 1 if name is same. Output in another column. Don't show the two columns. I don't need places also.
You could use this (I have considered the name of the table as HolyCow) :
SELECT holy.ID,
holy.Name,
SUM(holy.Cows) as '#ofCow',
SUM(holy.UItem) as 'UItem'
FROM HolyCow holy
GROUP BY holy.ID, holy.Name
ORDER BY holy.Name
Hope this helps!!