大约有 40,000 项符合查询结果（耗时：0.0319秒） [XML]
How to express a NOT IN query with ActiveRecord/Rails?
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Using Arel:
topics=Topic.arel_table
Topic.where(topics[:forum_id].not_in(@forum_ids))
or, if preferred:
topics=Topic.arel_table
Topic.where(topics[:forum_id].in(@forum_ids).not)
and since rails 4 on:
topics=Topic.arel_table
Topic.where.not(topics[:f...
How do I make a column unique and index it in a Ruby on Rails migration?
... What is the best way to do it? Also is there a way to index a column in a table?
8 Answers
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Hibernate show real SQL [duplicate]
...ent to your database.
this_ is an alias for that instance of the employee table.
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How to check if a function exists on a SQL database
...s for this type argument, particularly:
FN : Scalar function
IF : Inline table-valued function
TF : Table-valued-function
FS : Assembly (CLR) scalar-function
FT : Assembly (CLR) table-valued function
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How to select the rows with maximum values in each group with dplyr? [duplicate]
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For me, it helped to count the number of values per group. Copy the count table into a new object. Then filter for the max of the group based on the first grouping characteristic. For example:
count_table <- df %>%
group_by(A, B) %>%
count() %>%
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Why are C# interface methods not declared abstract or virtual?
...phic with regards to the interface type, so it needs a slot on the virtual table to allow virtual method dispatching.
– Jordão
Sep 1 '10 at 20:06
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A std::map that keep track of the order of insertion?
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You might combine a std::vector with a std::tr1::unordered_map (a hash table). Here's a link to Boost's documentation for unordered_map. You can use the vector to keep track of the insertion order and the hash table to do the frequent lookups. If you're doing hundreds of thousands of lookups,...
T-SQL: Selecting rows to delete via joins
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DELETE TableA
FROM TableA a
INNER JOIN TableB b
ON b.Bid = a.Bid
AND [my filter condition]
should work
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How to get the top 10 values in postgresql?
... *,
rank() over (order by some_value_column desc) as my_rank
from mytable) subquery
where my_rank <= 10
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Imitating a blink tag with CSS3 animations
... +animation(blink 1s 0s reverse infinite)
+transform(translateZ(0))
.table
display: table
height: 5em
width: 100%
vertical-align: middle
.cell
display: table-cell
width: 100%
height: 100%
vertical-align: middle
http://codepen.io/anon/pen/kaGxC (sass with bourbon)
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