大约有 44,000 项符合查询结果（耗时：0.0260秒） [XML]
MySQL CONCAT returns NULL if any field contain NULL
...
convert the NULL values with empty string by wrapping it in COALESCE
SELECT CONCAT(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS device_name
FROM devices
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How to remove a column from an existing table?
...lete a column from an unexisting table ;-)
BEGIN TRANSACTION
IF exists (SELECT * FROM sys.columns c
INNER JOIN sys.objects t ON (c.[object_id] = t.[object_id])
WHERE t.[object_id] = OBJECT_ID(N'[dbo].[MyTable]')
AND c.[name] = 'ColumnName')
BEGIN TRY
ALTER TABLE [dbo].[MyTable] DRO...
Xcode 4, Core Data Model Version - Set Current Version
...d "View" button at the top right of the window).
In the Utilities sidepane select the File inspector (little paper icon on the top left)
You will see "Versioned Core Data Model" as a group so just change the "Current" drop-down to your new version.
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How do I pass JavaScript variables to PHP?
...larieids">SalarieID:</label>
<?php
$query = "SELECT * FROM salarie";
$result = mysql_query($query);
if ($result) :
?>
<select id="salarieids" name="salarieid">
<?php
while ($row = mysql_fetch_assoc($r...
Evenly space multiple views within a container view
...constraint:
4) Adjust the constraint added in #3 above as follows:
a) select the constraint,
b) remove the constant (set to 0),
c) change the multiplier as follows: take the number of buttons + 1, and starting at the top, set the multiplier as buttonCountPlus1:1, and then buttonCountPlus1:2, ...
JavaScript: how to change form action attribute value based on selection?
I'm trying to change the form action based on the selected value from a dropdown menu.
5 Answers
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MySQL string replace
...
Yes, MySQL has a REPLACE() function:
mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
-> 'WwWwWw.mysql.com'
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_replace
Note that it's easier if you make that an alias when using SELECT
SEL...
GROUP BY to combine/concat a column [duplicate]
...
SELECT
[User], Activity,
STUFF(
(SELECT DISTINCT ',' + PageURL
FROM TableName
WHERE [User] = a.[User] AND Activity = a.Activity
FOR XML PATH (''))
, 1, 1, '') AS URL...
How to get the index of an item in a list in a single step?
...g different (e.g. on top of any IEnumerable<>).
Use the overload of Select which takes an index in the predicate, so you transform your list into an (index, value) pair:
var pair = myList.Select((Value, Index) => new { Value, Index })
.Single(p => p.Value.Prop == oProp...
Does PostgreSQL support “accent insensitive” collations?
...n unaccent() you can use with your example (where LIKE seems not needed).
SELECT *
FROM users
WHERE unaccent(name) = unaccent('João');
Index
To use an index for that kind of query, create an index on the expression. However, Postgres only accepts IMMUTABLE functions for indexes. If a functio...