大约有 40,000 项符合查询结果（耗时：0.0208秒） [XML]
Storing JSON in database vs. having a new column for each key
..._food pizza
.................
and query via something like this:
select meta_val from `table` where meta_key = 'name' and uid = 1 order by meta_id desc
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How to do 3 table JOIN in UPDATE query?
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This does an implicit JOIN in the same way doing SELECT * FROM TABLE_A, TABLE_B ... does
– Madbreaks
Sep 22 '15 at 22:26
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Array.push() if does not exist?
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Use a js library like underscore.js for these reasons exactly. Use: union: Computes the union of the passed-in arrays: the list of unique items, in order, that are present in one or more of the arrays.
_.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
=> [1, 2, 3, 101, 10]
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How to log PostgreSQL queries?
...ement = 'all'
#logging_collector = off to logging_collector = on
Optional: SELECT set_config('log_statement', 'all', true);
sudo /etc/init.d/postgresql restart or sudo service postgresql restart
Fire query in postgresql select 2+2
Find current log in /var/lib/pgsql/9.2/data/pg_log/
The log files t...
PostgreSQL: Is it better to use multiple databases with one schema each, or one database with multip
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A PostgreSQL "schema" is roughly the same as a MySQL "database". Having many databases on a PostgreSQL installation can get problematic; having many schemas will work with no trouble. So you definitely want to go with one database and multiple schemas within that database...
Hidden Features of Java
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Joint union in type parameter variance:
public class Baz<T extends Foo & Bar> {}
For example, if you wanted to take a parameter that's both Comparable and a Collection:
public static <A, B extends Collection<A&g...
SQL parser library for Java [closed]
... SQL_PARSER.createStatement(query); How can I get the Query body, i.e. the Select, From, Where, etc values?
– quarks
Apr 4 '15 at 17:56
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IntelliJ does not show 'Class' when we right click and select 'New'
... and must have something wrong because when we right click on a directory, select New and then get the context menu, Java based options are not shown. Currently get things like File, some HTML options, XML options.
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Count the occurrences of DISTINCT values
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SELECT name,COUNT(*) as count
FROM tablename
GROUP BY name
ORDER BY count DESC;
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Count(*) vs Count(1) - SQL Server
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The optimizer recognizes it for what it is: trivial.
The same as EXISTS (SELECT * ... or EXISTS (SELECT 1 ...
Example:
SELECT COUNT(1) FROM dbo.tab800krows
SELECT COUNT(1),FKID FROM dbo.tab800krows GROUP BY FKID
SELECT COUNT(*) FROM dbo.tab800krows
SELECT COUNT(*),FKID FROM dbo.tab800krows GROU...