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Mysql error 1452 - Cannot add or update a child row: a foreign key constraint fails
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Quite likely your sourcecodes_tags table contains sourcecode_id values that no longer exists in your sourcecodes table. You have to get rid of those first.
Here's a query that can find those IDs:
SELECT DISTINCT sourcecode_id FROM
sourcecodes_tags tags LEFT JOIN sourcecodes sc ON...
Cast an instance of a class to a @protocol in Objective-C
...c is a UIViewController object that conforms to MyProtocol", whereas using id <MyProtocol> translates to "vc is an object of an unknown class that conforms to MyProtocol".
This way the compiler will give you proper type checking on vc - the compiler will only give you a warning if any method ...
Rails params explained?
... Rails has a special syntax for making the params be a hash with hashes inside. For example, if the user's browser requested
http://www.example.com/?vote[item_id]=1&vote[user_id]=2
then params[:vote] would be a hash, params[:vote][:item_id] would be "1" and params[:vote][:user_id] would be "2...
XPath to find elements that does not have an id or class
How can I get all tr elements without id attribute?
4 Answers
4
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How can I pass selected row to commandLink inside dataTable or ui:repeat?
...ws, I want the user to be able to directly execute various actions on individual rows. For that, I have several <p:commandLink> s in the last column.
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Select Multiple Fields from List in Linq
... in your code:
var cats = listObject
.Select(i => new { i.category_id, i.category_name })
.Distinct()
.OrderByDescending(i => i.category_name)
.ToArray();
Since you (apparently) need to store it for later use, you could use the GroupBy operator:
Data[] cats = listObject
...
MySQL COUNT DISTINCT
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Select
Count(Distinct user_id) As countUsers
, Count(site_id) As countVisits
, site_id As site
From cp_visits
Where ts >= DATE_SUB(NOW(), INTERVAL 1 DAY)
Group By site_id
...
MongoDB, remove object from array
...
try..
db.mycollection.update(
{'_id': ObjectId("5150a1199fac0e6910000002")},
{ $pull: { "items" : { id: 23 } } },
false,
true
);
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Move to another EditText when Soft Keyboard Next is clicked on Android
...haviour of directional navigation by using following XML attributes:
android:nextFocusDown="@+id/.."
android:nextFocusLeft="@+id/.."
android:nextFocusRight="@+id/.."
android:nextFocusUp="@+id/.."
Besides directional navigation you can use tab navigation. For this you need to use
andr...
MySQL: How to copy rows, but change a few fields?
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INSERT INTO Table
( Event_ID
, col2
...
)
SELECT "155"
, col2
...
FROM Table WHERE Event_ID = "120"
Here, the col2, ... represent the remaining columns (the ones other than Event_ID) in ...