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Discuz! X3 论坛标题字数突破80的限制 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...你的表的前缀，还有修改前一定要备份！！！）
ALTER TABLE `pre_forum_post` CHANGE `subject` `subject` varchar(255) NOT NULL;
ALTER TABLE `pre_forum_rsscache` CHANGE `subject` `subject` varchar(255) NOT NULL;
ALTER TABLE `pre_forum_thread` CHANGE `subject` `subject` varchar(255...
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本帖最后由 zqp2013 于 2015-3-17 22:06 编辑
mysql：drop table if exists tablename;
不能写成
drop table tablename if exists tablename;
mysql：建立索引Sql
CREATE TABLE tablename (
`ID` &nbs...
How to write a simple database engine [closed]
...f it). I know most of the basic data structures taught in CS (trees, hash tables, lists, etc.) as well as a pretty good understanding of compiler theory (and have implemented a very simple interpreter) but I don't understand how to go about writing a database engine. I have searched for tutorials ...
Python subprocess.Popen “OSError: [Errno 12] Cannot allocate memory”
...as originally asked here but the bounty time expired even though an acceptable answer was not actually found. I am re-asking this question including all details provided in the original question.
...
The Role Manager feature has not been enabled
...thod will run just fine (if you haven't messed elsewhere) and create a few tables in your Database;
Press Ctrl+W+L to open the Server Explorer and you should be able to check in Data Connections > DefaultConnection > Tables the Roles and UsersInRoles tables among the newly created tables!
...
MySql export schema without data
...nsider using the --single-transaction option if you don't want or can't do table locks.
– Jim
Jan 22 '13 at 21:55
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DynamoDB vs MongoDB NoSQL [closed]
...can have multiple secondary global indexes. I'm doing queries on a single table with 4 possible filter parameters and sorting the results, this is supported (barely) through the use of the global secondary indexes with filter expressions. The problem comes in when you try to get the total results ...
Default implementation for Object.GetHashCode()
...d it is common to also provide ==/!=operators, and often to implement IEquatable<T> too.
For generating the hash code, it is common to use a factored sum, as this avoids collisions on paired values - for example, for a basic 2 field hash:
unchecked // disable overflow, for the unlikely possi...
Shortcuts in Objective-C to concatenate NSStrings
...ly as pleasant as just having a concatenation operator.
First, use an NSMutableString, which has an appendString method, removing some of the need for extra temp strings.
Second, use an NSArray to concatenate via the componentsJoinedByString method.
...
Set value to NULL in MySQL
...t NULL inside quotes in your update statement. This should work:
UPDATE table SET field = NULL WHERE something = something
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