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Random record in ActiveRecord
... for 100 randomly selected entries. (Be aware that it's RANDOM() in PostgreSQL and RAND() in MySQL ... not as portable as you may want it to be.)
– Florian Pilz
Jun 16 '11 at 13:17
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Use LINQ to get items in one List, that are not in another List
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Bit late to the party but a good solution which is also Linq to SQL compatible is:
List<string> list1 = new List<string>() { "1", "2", "3" };
List<string> list2 = new List<string>() { "2", "4" };
List<string> inList1ButNotList2 = (from o in list1
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How to concatenate strings of a string field in a PostgreSQL 'group by' query?
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PostgreSQL 9.0 or later:
Recent versions of Postgres (since late 2010) have the string_agg(expression, delimiter) function which will do exactly what the question asked for, even letting you specify the delimiter string:
SELECT co...
PostgreSQL Autoincrement
I'm switching from MySQL to PostgreSQL and was wondering how I can do autoincrement values. I saw in the PostgreSQL docs a datatype "serial", but I get syntax errors when using it (in v8.0).
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柳青：滴滴每天面临向死而生的挑战 永远热泪盈眶 - 资讯 - 清泛网 - 专注C/...
...家看看那一排是我们的高层管理者，其实他们都很年轻，包括James也是一张年轻的脸，每个深身上都有很独特的青春气息，这是非常难得的，这种就是年轻，就是热血。不知道有多少同学刚刚加入滴滴半年的时间，恭喜你们，你...
Quickly reading very large tables as dataframes
...ata is passed to and from R in a binary format, which is faster.) read.csv.sql in the sqldf package, as described in JD Long's answer, imports data into a temporary SQLite database and then reads it into R. See also: the RODBC package, and the reverse depends section of the DBI package page. MonetD...
Howto: Clean a mysql InnoDB storage engine?
Is it possible to clean a mysql innodb storage engine so it is not storing data from deleted tables?
2 Answers
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Similarity String Comparison in Java
... Here's an article showing how combine Levenshtein with an efficient SQL query: literatejava.com/sql/fuzzy-string-search-sql
– Thomas W
Apr 26 '14 at 2:11
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How to check if a table exists in a given schema
...tion in a function. Example:
Check if sequence exists in Postgres (plpgsql)
A query like above avoids possible exceptions and is therefore slightly faster.
to_regclass(rel_name) in Postgres 9.4+
Much simpler now:
SELECT to_regclass('schema_name.table_name');
Same as the cast, but it retur...
SSL is not enabled on the server
...uld establish DB connection without SSL encryption, like that:
db, err := sql.Open("postgres", "user=test password=test dbname=test sslmode=disable")
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