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Why is null an object and what's the difference between null and undefined?
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21 Answers
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What is the meaning of the CascadeType.ALL for a @ManyToOne JPA association
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edited May 1 '13 at 18:25
answered Oct 23 '12 at 9:33
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Unique constraint that allows empty values in MySQL
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183
Yes, you can do this. See the MySQL reference (version 5.5).
A UNIQUE index creates a cons...
Disable assertions in Python
...rt False"
Traceback (most recent call last):
File "<string>", line 1, in <module>
AssertionError
Note that by disable I mean it also does not execute the expression that follows it:
$ python -Oc "assert 1/0"
$ python -c "assert 1/0"
Traceback (most recent call last):
File "<st...
The differences between .build, .create, and .create! and when should they be used?
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edited May 23 '17 at 10:31
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111 silver badge
answered Dec 31 '08 at 18:26
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MySQL “NOT IN” query
I wanted to run a simple query to throw up all the rows of Table1 where a principal column value is not present in a column in another table ( Table2 ).
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Why is the time complexity of both DFS and BFS O( V + E )
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Your sum
v1 + (incident edges) + v2 + (incident edges) + .... + vn + (incident edges)
can be rewritten as
(v1 + v2 + ... + vn) + [(incident_edges v1) + (incident_edges v2) + ... + (incident_edges vn)]
and the first group is O(N) w...
When to use actors instead of messaging solutions such as WebSphere MQ or Tibco Rendezvous?
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edited May 23 '17 at 12:10
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111 silver badge
answered Oct 22 '12 at 19:15
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Access denied for user 'test'@'localhost' (using password: YES) except root user
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13 Answers
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Active
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Multiple columns index when using the declarative ORM extension of sqlalchemy
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139
those are just Column objects, index=True flag works normally:
class A(Base):
__tablename...