大约有 46,000 项符合查询结果（耗时：0.0167秒） [XML]
Return all enumerables with yield return at once; without looping through
...ods each returning an IEnumerable<ErrorInfo>, you can use Enumerable.Concat to make your code simpler:
private static IEnumerable<ErrorInfo> GetErrors(Card card)
{
return GetMoreErrors(card).Concat(GetOtherErrors())
.Concat(GetValidationErrors())
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Cast int to varchar
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@Pacerier IMO, using concat() to do a conversion isn't necessarily that intuitive. I'd prefer my code to be clear and that just doesn't make a whole lot of sense.
– Taryn♦
Apr 8 '15 at 12:19
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MySQL OPTIMIZE all tables?
...t;your_table>;, optimize all tables in a given schema like this: select concat('OPTIMIZE NO_WRITE_TO_BINLOG TABLE ',table_schema,'.',table_name,';') into outfile '/tmp/optimize_all_tables.sql' from information_schema.tables where table_schema = 'pabeta' and table_type = 'base table'; source /tmp/...
String concatenation vs. string substitution in Python
In Python, the where and when of using string concatenation versus string substitution eludes me. As the string concatenation has seen large boosts in performance, is this (becoming more) a stylistic decision rather than a practical one?
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Have Grunt generate index.html for different setups
...gt;/dist/<%= pkg.version %>/<%= now %>/<%= ver %>' which concats all vars (that's my build path). On my template I'll have: <script src="http://cdn.foo.com<!-- @echo path -->/js/bulldog.min.js"></script>. Anyway, I'm happy that I was able to save you some time! :D...
Is it possible to GROUP BY multiple columns using MySQL?
...ly this) group by two columns at same time, I just saw this point:
SELECT CONCAT (col1, '_', col2) AS Group1 ... GROUP BY Group1
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Postgresql GROUP_CONCAT equivalent?
I have a table and I'd like to pull one row per id with field values concatenated.
7 Answers
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Truncate all tables in a MySQL database in one command?
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truncate multiple database tables on Mysql instance
SELECT Concat('TRUNCATE TABLE ',table_schema,'.',TABLE_NAME, ';')
FROM INFORMATION_SCHEMA.TABLES where table_schema in ('db1_name','db2_name');
Use Query Result to truncate tables
Note:
may be you will get this error:
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Linq to SQL how to do “where [column] in (list of values)”
...ing the method in Jon Skeet's answer, but another one occurred to me using Concat. The Concat method performed slightly better in a limited test, but it's a hassle and I'll probably just stick with Contains, or maybe I'll write a helper method to do this for me. Either way, here's another option if ...
How do I kill all the processes in Mysql “show processlist”?
...n saves time. Do it in MySql itself:
Run these commands
mysql> select concat('KILL ',id,';') from information_schema.processlist
where user='root' and time > 200 into outfile '/tmp/a.txt';
mysql> source /tmp/a.txt;
Reference
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if you do not want to store in f...