I have currently setup a database where I store CSV's. I am reading more that CSV is bad practice in MYSQL.
My current setup is this:
----------------------------------------------
| id | Exercise | Set | Reps | date |
----------------------------------------------
| 1 | Value 1, | Value 1, | Value 1, | 01/01/16 |
| | Value 2, | Value 2, | Value 2, | |
| | Value 3, | Value 3, | Value 3, | |
----------------------------------------------
When a user is submitting data they can have 'AS MANY' new 'Exercise' inputs (and in turn values) added as they want (there could be up to 50) but only 10 'Set' and 'Reps'. For example:
<input name="exercise1[]">
<input name="set[]><input name="reps[]">
<input name="set[]><input name="reps[]">
<input name="set[]><input name="reps[]">
<input name="exercise2[]">
<input name="set1[]><input name="reps1[]">
<input name="set1[]><input name="reps1[]">
<input name="set1[]><input name="reps1[]">
This is the way it currently works and is working fine but I want to know:
Should I change they way I am storing this data?
If so, I'm unsure how I should save it. Is storing multiple rows for one form submission was a bad idea also?
The only way I can see to allow 'UNLIMITED' exercise values without CSV's is the way below (which uses multiple rows per form submission) and setting up 10 columns in my database for each 'set' and 'reps' (as I mentioned earlier there is only the possibility of 10 'Set' and 'Reps' values):
---------------------------------------------------------------------
| Exercise | Set | Reps | Set2 | Reps2 | date |
---------------------------------------------------------------------
| Value 1 | Value 1 | Value 2 | Value 1 | Value 2 | 01/01/16 |
---------------------------------------------------------------------
| Value 2 | Value 2 | Value 2 | Value 1 | Value 2 | 01/01/16 |
---------------------------------------------------------------------
| Value 3 | Value 3 | Value 3 | Value 1 | Value 2 | 01/01/16 |
---------------------------------------------------------------------
Please help me setup correctly before I go even further through my developing!
There are always different designs. Pick one best suits your situation.
1 - Design in one table as per your example when you pretty sure the structure is not changing, eg exactly x sets and y reps etc
id, excercise, set1, set2, set3, rep1, rep2, ...
2 - If unsure in data when growing, you can design a meta table:
id exercise_id meta value
-- ----------- ---- ---------
1 1 set1 value1
2 1 set2 value2
3 1 rep1 value3
4 2 set1 value5
....
3 - One-Many relationship tables - the traditional method:
exercises (id, date, ...)
exercise_sets(id, exercise_id, value)
exercise_reps(id, exercise_id, value)
Related
ID| Date1 | Date 2 |Total
-----------------------------------
1 | 15/02/2017 |02/02/2017 | 3 |
-----------------------------------
1 | 15/02/2017 |05/08/2017 | 3 |
-----------------------------------
1 | 15/02/2017 |12/12/2017 | 3 |
-----------------------------------
2 | 12/05/2017 |07/08/2017 | 2 |
-----------------------------------
2 | 12/05/2017 |10/08/2017 | 2 |
I have a table that is displaying data like above. I'm grouping that data on "ID" column. Values for Columns "Date1" & "Total" for a particular "ID" are the same but "Date2" value can be different in a given group.
How can i merge the cells across rows when the values are the same such that it displays like below?
ID| Date1 | Date 2 |Total
-----------------------------------
1 | 15/02/2017 |02/02/2017 | 3 |
--| |------------| |
1 | |05/08/2017 | |
--| |------------| |
1 | |12/12/2017 | |
---------------------------------|
2 | 12/05/2017 |07/08/2017 | 2 |
--| |------------| |
2 | |10/08/2017 | |
I did manage to find that "HideDuplicates" TextBox property, but while that will suppress the repetition of the cell values in adjacent rows it does not merge those duplicate cells down the column across rows
Its difficult to tell how the report is setup in terms of groups etc without seeing the design, but this is pretty simple to do from scratch.
Start with a simple table with just your detail rows, no grouping. Then right-click the detail row in the row group panel under the main report design area. Choose Add Group -> Parent Group
Choose your Date1 field in the group by drop down . Click OK and you're done.
Hello i want to split a resulting column in multiple columns just like on the link. But number of columns are not specific ;
Example
COL1 | OTHER COLUMNS
----------------------------------------
this,will,split | some value
also,this | some value
this,is,four,columns | some value
I want make this something like that ;
COL1 | COL2 | COL3 | COL4 | OTHER
----------------------------------------
this | will | split| NULL | some value
also | this | NULL | NULL | some value
this | is | four | columns| some value
edit
it looks like similar that question but not:
Can you split/explode a field in a MySQL query?
I want results in 1 row, I dont want something like that;
RESULT
-----
this
will
split
...
on that question you can see there is specific number of cols. bu i dont. :(
How to split a resulting column in multiple columns
I think you can create one relational table and add multiple entry in relational table, hear you don't need to think about column, you have to add entry in row.
eg.
Table 1:
ID | COL1 | OTHER COLUMNS
----------------------------------------
1 |this,will,split | some value
2 |also,this | some value
3 |this,is,four,columns | some value
Table2
ID | Table1_id | value
-------------------------
1 | 1 | this
2 | 1 | will
3 | 1 | split
4 | 2 | also
5 | 2 | this
6 | 3 | this
6 | 3 | is
6 | 3 | four
6 | 3 | columns
Please check this, i think fix your problem.
I added a new column in one of my database tables. I'd like to try to populate that column for previous records. New records will be validated through forms. Here is an example.
| Quantity | Description | Price | Amount | Type |
----------------------------------------------------------
| 3 | Storage for Pallets | 3.99 | 11.97 | NULL |
| 3 | Handling for Pallets| 3.99 | 11.97 | NULL |
| 3 | Misc expense | 3.99 | 11.97 | NULL |
----------------------------------------------------------
I'd like to replace those null values based off of keywords in the description. For example the updated table would look like the following.
| Quantity | Description | Price | Amount | Type |
--------------------------------------------------------------
| 3 | Storage for Pallets | 3.99 | 11.97 | Storage |
| 3 | Handling for Pallets| 3.99 | 11.97 | Handling |
| 3 | Misc expense | 3.99 | 11.97 | Misc |
--------------------------------------------------------------
Any ideas on an update statement that will accomplish this?
Because there is no primary key you have put the values into the where clause for all columns' values. Or at least enough so that there is no chance of the update hitting 2+ rows, based on your knowledge of the data.
Here is the first update as an example:
update tbl
set "Type" = 'Storage'
where "Quantity" = 3
and "Description" = 'Storage for Pallets'
and "Price" = 3.99
and "Amount" = 11.97;
Fiddle:
http://sqlfiddle.com/#!12/9fa64/1/0
If there were a primary key, your WHERE clause would be a lot simpler:
where pk_id_field = x
(Because you could rest assured knowing you're about to update the exact row needed, and that no other rows have that value)
It was simpler than I thought
UPDATE
invoice_line_items
SET
line_item_type = "Storage"
WHERE
description like "%storage%";
.....and so on
Actually: If you always want the description's first word for the type, you can go with
UPDATE Invoice_Line_Items
SET line_item_type = SUBSTRING_INDEX(description, ' ', 1);
See SQL Fiddle. You could, of course, add a WHERE clause, if it is not just as straightforward for the whole table… And you are not limited to the first word either…
I have a table of users where 1 column stores user's "roles".
We can assign multiple roles to particular user.
Then I want to store role IDs in the "roles" column.
But how can I store multiple values into a single column to save memory in a way that is easy to use? For example, storing using a comma-delimited field is not easy and uses memory.
Any ideas?
If a user can have multiple roles, it is probably better to have a user_role table that stores this information. It is normalised, and will be much easier to query.
A table like:
user_id | role
--------+-----------------
1 | Admin
2 | User
2 | Admin
3 | User
3 | Author
Will allow you to query for all users with a particular role, such as SELECT user_id, user.name FROM user_role JOIN user WHERE role='Admin' rather than having to use string parsing to get details out of a column.
Amongst other things this will be faster, as you can index the columns properly and will take marginally more space than any solution that puts multiple values into a single column - which is antithetical to what relational databases are designed for.
The reason this shouldn't be stored is that it is inefficient, for the reason DCoder states on the comment to this answer. To check if a user has a role, every row of the user table will need to be scanned, and then the "roles" column will have to be scanned using string matching - regardless of how this action is exposed, the RMDBS will need to perform string operations to parse the content. These are very expensive operations, and not at all good database design.
If you need to have a single column, I would strongly suggest that you no longer have a technical problem, but a people management one. Adding additional tables to an existing database that is under development, should not be difficult. If this isn't something you are authorised to do, explain to why the extra table is needed to the right person - because munging multiple values into a single column is a bad, bad idea.
You can also use bitwise logic with MySQL. role_id must be in BASE 2 (0, 1, 2, 4, 8, 16, 32...)
role_id | label
--------+-----------------
1 | Admin
2 | User
4 | Author
user_id | name | role
--------+-----------------
1 | John | 1
2 | Steve | 3
3 | Jack | 6
Bitwise logic allows you to select all user roles
SELECT * FROM users WHERE role & 1
-- returns all Admin users
SELECT * FROM users WHERE role & 5
-- returns all users who are admin or Author because 5 = 1 + 4
SELECT * FROM users WHERE role & 6
-- returns all users who are User or Author because 6 = 2 + 4
From your question what I got,
Suppose, you have to table. one is "meal" table and another one is "combo_meal" table. Now I think you want to store multiple meal_id inside one combo_meal_id without separating coma[,]. And you said that it'll make your DB to more standard.
If I not getting wrong from your question then please read carefully my suggestion bellow. It may be help you.
First think is your concept is right. Definitely it'll give you more standard DB.
For this you have to create one more table [ example table: combo_meal_relation ] for referencing those two table data. May be one visible example will clear it.
meal table
+------+--------+-----------+---------+
| id | name | serving | price |
+------+--------+-----------+---------+
| 1 | soup1 | 2 person | 12.50 |
+------+--------+-----------+---------+
| 2 | soup2 | 2 person | 15.50 |
+------+--------+-----------+---------+
| 3 | soup3 | 2 person | 23.00 |
+------+--------+-----------+---------+
| 4 | drink1 | 2 person | 4.50 |
+------+--------+-----------+---------+
| 5 | drink2 | 2 person | 3.50 |
+------+--------+-----------+---------+
| 6 | drink3 | 2 person | 5.50 |
+------+--------+-----------+---------+
| 7 | frui1 | 2 person | 3.00 |
+------+--------+-----------+---------+
| 8 | fruit2 | 2 person | 3.50 |
+------+--------+-----------+---------+
| 9 | fruit3 | 2 person | 4.50 |
+------+--------+-----------+---------+
combo_meal table
+------+--------------+-----------+
| id | combo_name | serving |
+------+--------------+-----------+
| 1 | combo1 | 2 person |
+------+--------------+-----------+
| 2 | combo2 | 2 person |
+------+--------------+-----------+
| 4 | combo3 | 2 person |
+------+--------------+-----------+
combo_meal_relation
+------+--------------+-----------+
| id | combo_meal_id| meal_id |
+------+--------------+-----------+
| 1 | 1 | 1 |
+------+--------------+-----------+
| 2 | 1 | 2 |
+------+--------------+-----------+
| 3 | 1 | 3 |
+------+--------------+-----------+
| 4 | 2 | 4 |
+------+--------------+-----------+
| 5 | 2 | 2 |
+------+--------------+-----------+
| 6 | 2 | 7 |
+------+--------------+-----------+
When you search inside table then it'll generate faster result.
search query:
SELECT m.*
FROM combo_meal cm
JOIN meal m
ON m.id = cm.meal_id
WHERE cm.combo_id = 1
Hopefully you understand :)
You could do something like this
INSERT INTO table (id, roles) VALUES ('', '2,3,4');
Then to find it use FIND_IN_SET
As you might already know, storing multiple values in a cell goes against 1NF form. If youre fine with that, using a json column type is a great way and has good methods to query properly.
SELECT * FROM table_name
WHERE JSON_CONTAINS(column_name, '"value 2"', '$')
Will return any entry with json data like
[
"value",
"value 2",
"value 3"
]
Youre using json, so remember, youre query performance will go down the drain.
I have table:
+----+--------+----------+
| id | doc_id | next_req |
+----+--------+----------+
| 1 | 1 | 4 |
| 2 | 1 | 3 |
| 3 | 1 | 0 |
| 4 | 1 | 2 |
+----+--------+----------+
id - auto incerement primary key.
nex_req - represent an order of records. (next_req = id of record)
How can I build a SQL query get records in this order:
+----+--------+----------+
| id | doc_id | next_req |
+----+--------+----------+
| 1 | 1 | 4 |
| 4 | 1 | 2 |
| 2 | 1 | 3 |
| 3 | 1 | 0 |
+----+--------+----------+
Explains:
record1 with id=1 and next_req=4 means: next must be record4 with id=4 and next_req=2
record4 with id=5 and next_req=2 means: next must be record2 with id=2 and next_req=3
record2 with id=2 and next_req=3 means: next must be record3 with id=1 and next_req=0
record3 with id=3 and next_req=0: means that this is a last record
I need to store an order of records in table. It's important fo me.
If you can, change your table format. Rather than naming the next record, mark the records in order so you can use a natural SQL sort:
+----+--------+------+
| id | doc_id | sort |
+----+--------+------+
| 1 | 1 | 1 |
| 4 | 1 | 2 |
| 2 | 1 | 3 |
| 3 | 1 | 4 |
+----+--------+------+
Then you can even cluster-index on doc_id,sort for if you need to for performance issues. And honestly, if you need to re-order rows, it is not any more work than a linked-list like you were working with.
Am able to give you a solution in Oracle,
select id,doc_id,next_req from table2
start with id =
(select id from table2 where rowid=(select min(rowid) from table2))
connect by prior next_req=id
fiddle_demo
I'd suggest to modify your table and add another column OrderNumber, so eventually it would be easy to order by this column.
Though there may be problems with this approach:
1) You have existing table and need to set OrderNumber column values. I guess this part is easy. You can simply set initial zero values and add a CURSOR for example moving through your records and incrementing your order number value.
2) When new row appears in your table, you have to modify your OrderNumber, but here it depends on your particular situation. If you only need to add items to the end of the list then you can set your new value as MAX + 1. In another situation you may try writing TRIGGER on inserting new items and calling similar steps to point 1). This may cause very bad hit on performance, so you have to carefully investigate your architecture and maybe modify this unusual construction.