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How to declare a variable in MySQL?
...at has not been
initialized, it has a value of NULL and a type of string.
SELECT @var_any_var_name
You can initialize a variable using SET or SELECT statement:
SET @start = 1, @finish = 10;
or
SELECT @start := 1, @finish := 10;
SELECT * FROM places WHERE place BETWEEN @start AND @finish...
MySQL - Get row number on select
Can I run a select statement and get the row number if the items are sorted?
5 Answers
...
error, string or binary data would be truncated when trying to insert
...ay cause it.
In my case i was creating the table with a field like this:
Select '' as Period, * From Transactions Into #NewTable
Therefore the field "Period" had a length of Zero and causing the Insert operations to fail. I changed it to "XXXXXX" that is the length of the incoming data and it n...
MySQL SELECT WHERE datetime matches day (and not necessarily time)
...
NEVER EVER use a selector like DATE(datecolumns) = '2012-12-24' - it is a performance killer:
it will calculate DATE() for all rows, including those, that don't match
it will make it impossible to use an index for the query
It is much fas...
Is there an SQLite equivalent to MySQL's DESCRIBE [table]?
...aster table:
sqlite> CREATE TABLE foo (bar INT, quux TEXT);
sqlite> SELECT * FROM sqlite_master;
table|foo|foo|2|CREATE TABLE foo (bar INT, quux TEXT)
sqlite> SELECT sql FROM sqlite_master WHERE name = 'foo';
CREATE TABLE foo (bar INT, quux TEXT)
...
Using backticks around field names
...backticks, I would assume it lets you get away with ridiculous stuff like
SELECT `id`, `my name`, `another field` , `field,with,comma`
Which does of course generate badly named tables.
If you're just being concise I don't see a problem with it,
you'll note if you run your query as such
EXPLA...
Random record in ActiveRecord
...he first, all after are still sorted by id). If you need multiple randomly selected records you must use this approach multiple times or use the random order method provided by your database, i.e. Thing.order("RANDOM()").limit(100) for 100 randomly selected entries. (Be aware that it's RANDOM() in P...
MySQL date format DD/MM/YYYY select query?
...ably just want to format the output date? then this is what you are after
SELECT *, DATE_FORMAT(date,'%d/%m/%Y') AS niceDate
FROM table
ORDER BY date DESC
LIMIT 0,14
Or do you actually want to sort by Day before Month before Year?
...
How to merge 2 List and removing duplicate values from it in C#
...
Have you had a look at Enumerable.Union
This method excludes duplicates from the return set. This is different
behavior to the Concat
method, which returns all the elements
in the input sequences including
duplicates.
List<int> list1 = new List<int...
linux下iptables配置详解 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...tables -Z -t nat
2,添加规则
添加基本的NAT地址转换,(关于如何配置NAT可以看我的另一篇文章),
添加规则,我们只添加DROP链.因为默认链全是ACCEPT.
防止外网用内网IP欺骗
[root@tp sysconfig]# iptables -t nat -A PREROUTING -i eth0 -s 10.0.0.0/8 -j DRO...