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SQL join on multiple columns in same tables
... subqueries, but I'm having trouble joining columns together from the same tables. I tried:
2 Answers
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Is there a combination of “LIKE” and “IN” in SQL?
...an use REGEXP_LIKE (available from Oracle version 10 onwards).
An example table:
SQL> create table mytable (something)
2 as
3 select 'blabla' from dual union all
4 select 'notbla' from dual union all
5 select 'ofooof' from dual union all
6 select 'ofofof' from dual union all
7 ...
How to hide first section header in UITableView (grouped style)
As the design of table views using the grouped style changed considerably with iOS 7, I would like to hide (or remove) the first section header. So far I haven't managed to achieve it.
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Can hash tables really be O(1)?
It seems to be common knowledge that hash tables can achieve O(1), but that has never made sense to me. Can someone please explain it? Here are two situations that come to mind:
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sqlalchemy unique across multiple columns
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UniqueConstraint or Index constructs explicitly.
As these belong to a Table and not to a mapped Class, one declares those in the table definition, or if using declarative as in the __table_args__:
# version1: table definition
mytable = Table('mytable', meta,
# ...
Column('customer_id',...
初窥InnoDB的Memcached插件 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...件所需要的配置信息：
mysql> USE innodb_memcache
mysql> SHOW TABLES;
+---------------------------+
| Tables_in_innodb_memcache |
+---------------------------+
| cache_policies |
| config_options |
| containers |
+---------------------------+
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Does MySQL index foreign key columns automatically?
...
Yes, but only on innodb. Innodb is currently the only shipped table format that has foreign keys implemented.
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SQL Joins Vs SQL Subqueries (Performance)?
...ies with Semijoin Transformations
Rewriting Subqueries as Joins
I have a table with 50000 elements, the result i was looking for was 739 elements.
My query at first was this:
SELECT p.id,
p.fixedId,
p.azienda_id,
p.categoria_id,
p.linea,
p.tipo,
p.nome
FROM prodotto p
WH...
How can I define a composite primary key in SQL?
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Just for clarification: a table can have at most one primary key. A primary key consists of one or more columns (from that table). If a primary key consists of two or more columns it is called a composite primary key. It is defined as follows:
CREATE...
SQL standard to escape column names?
...ing to SQLite,
'foo' is an SQL string
"foo" is an SQL identifier (column/table/etc)
[foo] is an identifier in MS SQL
`foo` is an identifier in MySQL
For qualified names, the syntax is: "t"."foo" or [t].[foo], etc.
MySQL supports the standard "foo" when the ANSI_QUOTES option is enabled.
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