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error: command 'gcc' failed with exit status 1 while installing eventlet
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16 Answers
16
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Does MySQL ignore null values on unique constraints?
...ws multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);
INSERT table1 VALUES (NULL);
SELECT * FROM table1;
Result:
x
NULL
NULL
1
This i...
select and update database record with a single queryset
...et object update method:
MyModel.objects.filter(pk=some_value).update(field1='some value')
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Check if my app has a new version on AppStore
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91
Here is a simple code snippet that lets you know if the current version is different
-(BOOL) ne...
Display two files side by side
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167
You can use pr to do this, using the -m flag to merge the files, one per column, and -t to omi...
How do I return multiple values from a function? [closed]
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14 Answers
14
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Why is i++ not atomic?
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125
i++ is probably not atomic in Java because atomicity is a special requirement which is not pre...
Cluster analysis in R: determine the optimal number of clusters
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1024
If your question is how can I determine how many clusters are appropriate for a kmeans analys...
Avoid duplicates in INSERT INTO SELECT query in SQL Server
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Using NOT EXISTS:
INSERT INTO TABLE_2
(id, name)
SELECT t1.id,
t1.name
FROM TABLE_1 t1
WHERE NOT EXISTS(SELECT id
FROM TABLE_2 t2
WHERE t2.id = t1.id)
Using NOT IN:
INSERT INTO TABLE_2
(id, name)
SELECT t1.id,
t1.name
F...