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Can I concatenate multiple MySQL rows into one field?
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You can use GROUP_CONCAT:
SELECT person_id, GROUP_CONCAT(hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Ludwig stated in his comment, you can add the DISTINCT operator to avoid duplicates:
SELECT person_id, GROUP_CONCAT(DISTINCT ...
JOIN queries vs multiple queries
...han several queries? (You run your main query, and then you run many other SELECTs based on the results from your main query)
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mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to
I am trying to select data from a MySQL table, but I get one of the following error messages:
31 Answers
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what is the difference between GROUP BY and ORDER BY in sql
... SUM, COUNT, AVG, etc).
TABLE:
ID NAME
1 Peter
2 John
3 Greg
4 Peter
SELECT *
FROM TABLE
ORDER BY NAME
=
3 Greg
2 John
1 Peter
4 Peter
SELECT Count(ID), NAME
FROM TABLE
GROUP BY NAME
=
1 Greg
1 John
2 Peter
SELECT NAME
FROM TABLE
GROUP BY NAME
HAVING Count(ID) > 1
=
Peter
...
SQL RANK() versus ROW_NUMBER()
...he first 3 rows are tied when ordered by ID)
WITH T(StyleID, ID)
AS (SELECT 1,1 UNION ALL
SELECT 1,1 UNION ALL
SELECT 1,1 UNION ALL
SELECT 1,2)
SELECT *,
RANK() OVER(PARTITION BY StyleID ORDER BY ID) AS 'RANK',
ROW_NUMBER() OVER(PARTITION BY Style...
How can I set the default value for an HTML element?
I thought that adding a "value" attribute set on the <select> element below would cause the <option> containing my provided "value" to be selected by default:
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LINQ query to select top five
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var list = (from t in ctn.Items
where t.DeliverySelection == true && t.Delivery.SentForDelivery == null
orderby t.Delivery.SubmissionDate
select t).Take(5);
share
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PostgreSQL - fetch the row which has the Max value for a column
...sted index lookup into lives - on my machine
-- the latter query plan was selected given my memory settings and
-- histogram
SELECT
l1.*
FROM
lives AS l1
INNER JOIN (
SELECT
usr_id,
MAX(time_stamp) AS time_stamp_max
FROM
lives
GROUP BY
usr_id
) AS l2
...
How to use GROUP_CONCAT in a CONCAT in MySQL
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select id, group_concat(`Name` separator ',') as `ColumnName`
from
(
select
id,
concat(`Name`, ':', group_concat(`Value` separator ',')) as `Name`
from mytbl
group by
id,
`Name`
) tbl
group by id;
...
Populating a razor dropdownlist from a List in MVC
...leaner separation.
First create a viewmodel to store the Id the user will select along with a list of items that will appear in the DropDown.
ViewModel:
public class UserRoleViewModel
{
// Display Attribute will appear in the Html.LabelFor
[Display(Name = "User Role")]
public int Sele...