I have a special scenario to fetch "unique" row.
Let's say the database is like below
| id | userid | value | others |
|----|--------|-------|---------|
| 1 | 111 | 10 | string1 |
| 2 | 112 | 30 | string2 |
| 3 | 112 | 30 | string3 |
| 4 | 113 | 50 | string4 |
what I want to achieve is to fetch the unique rows based on the "userid" so I'am able to sum all values.
the expect output row can be either id: 1 2 4 or 1 3 4 (both is acceptable for this special case because same id guarantees same value, or in general, get just one row from those row with same userid. ), so the sum will be 90.
Note: DB is extended from Eloquent\model
My old approach is to get DB::unique('userid'); then for each userid DB::where('userid', $id)->value('value'), add the result to sum; I just believe there might be a better approach.
There is Illuminate\Support\Facades\DB in Laravel, it can return the Query Builder. Not recommend to use a model that is named DB.
So just change another name.
By the way, for Eloquent\Model, you can use groupBy and sum too:
Model::groupBy('user_id')->sum('value');
Related
I have two columns in my database that I want to combine before matching them using LIKE statement.
My table:
|---------------------------------|
| ID | PREFIX | SUFFIX |
|---------------------------------|
| 1 | 31 | 523 |
|---------------------------------|
| 2 | 62 | 364 |
|---------------------------------|
I want to be able to supply 315 and ID 1 would be returned. Is there any easy way of doing it? At the moment I am splitting search string and matching separate columns.
Thanks.
SELECT * FROM table WHERE CONCAT(PREFIX, SUFFIX) LIKE '%315%'
I want to return only one column as output in MySQL.
This works:
select COALESCE(sum(debit_amt),0) as credit from client_debit_bal where mob_no=id
but when I try the following query it does not:
select COALESCE(sum(debit_amt),0) as credit from client_debit_bal where mob_no=id
and cmy_code='001'
I only need credit to be outputted. What am I missing?
Are you looking for LIMIT?
LIMIT clause constrains the number of result.
You can fetch the first N rows using LIMIT [N].
Suppose there is a table like following,
tbl_t
| idx | name | age |
| 0 | Tom | 30 |
| 1 | Jerry | 25 |
| 2 | Bob | 30 |
| 3 | Ken | 45 |
Then query following statement,
SELECT name FROM tbl_t WHERE age=30
result would be {'Tom', 'Bob'}.
But if you query SELECT name FROM tbl_t WHERE age=30 LIMIT 1 then
result would be {'Tom'}.
If you want to get further information, visit http://www.mysqltutorial.org/mysql-limit.aspx .
I need to store a set of numbers in a MySQL database. I need some help to determine the best table structure to use.
There are 20 numbers that will be stored in each row, along with an ID. The numbers can range from 1 - 80 and there are no repeats in this series of numbers.
Initially I created a table structure with 21 columns, an ID and 20 columns that store each individual number.
Id | Num1 | Num2 | Num3 | Num4 | Num5 | etc.. |
----------------------------------------------------------
0001 | 1 | 4 | 15 | 22 | 39 | 43 |
0002 | 3 | 5 | 22 | 43 | 55 | 58 |
0003 | 1 | 3 | 5 | 6 | 15 | 26 |
I've also thought of a table with 81 columns, an ID and 80 boolean columns that would represent each individual number.
Id | 1 | 2 | 3 | 4 | 5 | etc.. |
----------------------------------------------------------
0001 | True | False | False | True | True | False |
0002 | False | False | True | False | True | False |
0003 | True | False | True | False | True | True |
Can anyone give some advice to the pros and cons of each table structure, and which would be easier to use when searching this table.
For example, we would need to search for every row that contains 1,2,5,66, and 79.
Or every row that contains 16,33, and 4.
Any guidence would be appreciated.
What you're looking for is called database normalization; a way to organize data that prevents duplication and anomalies (like changing one record inadvertently changing another record).
Higher-normal forms depend on the meaning of your data, which you have not told us, but to start you should avoid ordered or indeterminate columns (like Num1, Num2, ...) and split your columns into rows:
ID Num
0001 1
0001 4
0001 15
...
0002 3
0002 5
...
In general, any time you find yourself adding a bunch of columns that depend on their position you are making a mistake. SQL has many functions for aggregating, combining, sorting, and reporting on rows. Use the features of SQL to produce the results you want; don't try to make your database schema look like the final printed report.
In answer to your comment, a query that returns only IDs that have Nums 1, 4, and 15, and no other ID:
select ID from YourTable
where Num in (1, 4, 15)
group by ID
having Count(ID) = 3
If Nums can be duplicated you will want something like having count(distinct ID). If you can have different counts of Nums to match you will have to create a temporary table of Nums to match and use having count(ID) = (select Count(Num) from TemporaryTable).
Note that SQL Server already has a master..spt_values table of integers to use in such situations; I do not know if MySql has such a thing, but they are easy to generate if you need one.
I have two mysql tables as
Component
+----+-------------------------+--------+
| OldComponentId | NewComponentId |
+----+-------------------------+--------+
| 15 | 85 |
| 16 | 86 |
| 17 | 87 |
+----+-------------------------+--------+
Formulae
+----+-------------------------+--------+
| id | formula_string |
+----+-------------------------+--------+
| 1 | A+15-16+17 |
| 2 | 16+15-17 |
+----+-------------------------+--------+
I want to replace value of formula_string on the basis of NewComponentId as
Formulae
+----+-------------------------+--------+
| id | formula_string |
+----+-------------------------+--------+
| 1 | A+85-86+87 |
| 2 | 86+85-87 |
+----+-------------------------+--------+
I have tried with following mysql query but its not working
update Formulae fr, Component comp set formula_string=REPLACE(fr.formula_string,comp.OldComponentId,comp.NewComponentId).
Please suggest the solutions
thanks.
There is no easy way to do this. As you observed in your update statement, the replacements don't nest. They just replace one at a time.
One thing that you can do is:
update Formulae fr cross join
Component comp
set formula_string = REPLACE(fr.formula_string, comp.OldComponentId, comp.NewComponentId)
where formula_string like concat('%', comp.OldComponentId, '%')
Then continue running this until row_count() returns 0.
Do note that your structure could result in infinite loops (if A --> B and B --> A). You also have a problem of "confusion" so 10 would be replaced in 100. This suggests that your overall data structure may not be correct. Perhaps you should break up the formula into separate pieces. If they are just numbers and + and -, you can have a junction table with the value and the sign for each component. Then your query would be much easier.
Basically, I have a list of records in a mysql db. These records are ordered 1 to 10. The user can re-order these records to whatever order they want. They will press a button to update all the records to their newly, respective order number. For example:
ID | Sort_Index | Name
----------------------
1 | 1 | Jim
2 | 2 | Bob
3 | 3 | Carl
4 | 4 | Bill
5 | 5 | Wendy
The user can change these to this for example:
Note: the changed values are stored into an array before I make the UPDATE calls
ID | Sort_Index | Name
----------------------
1 | 1 | Carl
2 | 2 | Wendy
3 | 3 | Bob
4 | 4 | Jim
5 | 5 | Bill
My question is, how can I make this mysql call with one call, using the new values in my array, instead of one call for each record?
If this is impossible or simply the "wrong way to do it", please feel free to suggest new ideas as I am not fully committed to this idea as of now.
If you have a limited number of rows, you could implement this with an sql CASE statement --
Update users set sort_index = case id when 1 then <newval> when 2 then <newval>...