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Create boolean column in MySQL with false as default value?
... into mytable () values ();
Query OK, 1 row affected (0.00 sec)
mysql> select * from mytable;
+--------+
| mybool |
+--------+
| 0 |
+--------+
1 row in set (0.00 sec)
FYI: My test was done on the following version of MySQL:
mysql> select version();
+----------------+
| version() ...
CREATE TABLE IF NOT EXISTS equivalent in SQL Server [duplicate]
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if not exists (select * from sysobjects where name='cars' and xtype='U')
create table cars (
Name varchar(64) not null
)
go
The above will create a table called cars if the table does not already exist.
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NSInvalidUnarchiveOperationException: Could not instantiate class named NSLayoutConstraint
...the first tab in the left hand side inspector, when you have File's owner) selected.
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Should I use “hasClass” before “addClass”? [duplicate]
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Hey Jon :) It is mouse selectable as well.. (click on line number and shift+click on another to select all lines..)
– Gabriele Petrioli
Nov 13 '12 at 10:30
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解决：ORA-00054:资源正忙,要求指定NOWAIT - 数据库(内核) - 清泛网 - 专注...
...删除
1：找出所有被锁的对象，定位出哪个回话占用
select l.session_id,o.owner,o.object_name from v$locked_object l,dba_objects o where l.object_id=o.object_id
结果：
session_id owner object_name
158 SA TEST_1
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对比想要创建的索引，定位哪些会话需要...
MongoDB仿关系型数据库Group聚合例子 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...系型数据库例子，通过BsonJavaScript脚本实现。相当的SQL：select * from GroupDemo a right join (select userName,max(date) maxdate from GroupDemo group by userName) b on a date=b maxdate
namespace MongoGroupDemo
{
class Program
{
private static string MongoConnStr...
Linq 多字段排序，二次排序 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...ed = source.OrderByDescending( t => t.f1 ).ThenBy( t => t.f2 );类似SQL：select * from t1 order by f1 d...Linq：ordered = source.OrderByDescending( t => t.f1 ).ThenBy( t => t.f2 );
类似SQL：select * from t1 order by f1 desc ,f2 asc
这种写法里 OrderBy、ThenBy 是升序的，OrderByD...
Postgres dump of only parts of tables for a dev snapshot
...r larger tables you can use the COPY command to pull out subsets...
COPY (SELECT * FROM mytable WHERE ...) TO '/tmp/myfile.tsv'
COPY mytable FROM 'myfile.tsv'
https://www.postgresql.org/docs/current/static/sql-copy.html
You should consider maintaining a set of development data rather than just ...
How to use SQL Order By statement to sort results case insensitive?
...You can just convert everything to lowercase for the purposes of sorting:
SELECT * FROM NOTES ORDER BY LOWER(title);
If you want to make sure that the uppercase ones still end up ahead of the lowercase ones, just add that as a secondary sort:
SELECT * FROM NOTES ORDER BY LOWER(title), title;
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Algorithm to return all combinations of k elements from n
... takes an array of letters as an argument and a number of those letters to select.
71 Answers
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