大约有 44,000 项符合查询结果（耗时：0.0342秒） [XML]
Which SQL query is faster? Filter on Join criteria or Where clause?
...INNER JOIN with a LEFT JOIN.
In your very case this will look like this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAID = a.ID
AND a.ID = 1
LEFT JOIN
TableB b
ON x.TableBID = b.ID
or this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x...
How to find all tables that have foreign keys that reference particular table.column and have values
...
Here you go:
USE information_schema;
SELECT *
FROM
KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_NAME = 'X'
AND REFERENCED_COLUMN_NAME = 'X_id';
If you have multiple databases with similar tables/column names you may also wish to limit your query to a particul...
Linq Syntax - Selecting multiple columns
...
.Where(x => x.EMAIL == givenInfo || x.USER_NAME == givenInfo)
.Select(x => new { x.EMAIL, x.ID });
AFAIK, the declarative LINQ syntax is converted to a method call chain similar to this when it is compiled.
UPDATE
If you want the entire object, then you just have to omit the call ...
Reading large text files with streams in C#
...to memory, loads faster as it doesn't make a new string every time you add chars)
– Joshua G
Jan 20 '16 at 15:01
...
How can I tell when a MySQL table was last updated?
...e information_schema database to tell you when another table was updated:
SELECT UPDATE_TIME
FROM information_schema.tables
WHERE TABLE_SCHEMA = 'dbname'
AND TABLE_NAME = 'tabname'
This does of course mean opening a connection to the database.
An alternative option would be to "touch" a ...
Why does Git treat this text file as a binary file?
... inspected the file's contents it has seen stuff that isn't in basic ascii characters. Being UTF16 I expect that it will have 'funny' characters so it thinks it's binary.
There are ways of telling git if you have internationalisation (i18n) or extended character formats for the file. I'm not suffic...
Why should I declare a virtual destructor for an abstract class in C++?
...
{
public:
virtual void DoFoo() = 0;
};
class Bar : public IFoo
{
char* dooby = NULL;
public:
virtual void DoFoo() { dooby = new char[10]; }
void ~Bar() { delete [] dooby; }
};
IFoo* baz = new Bar();
baz->DoFoo();
delete baz; // memory leak - dooby isn't deleted
...
CSS Input with width: 100% goes outside parent's bound
...il" class="login-field">
<label for="email" style="-moz-user-select: none;-webkit-user-select: none;" onselectstart="return false;">E-mail address</label>
<span><input name="email" id="email" type="text" /></span>
</div>
<div clas...
How do you beta test an iphone app?
...file
Start the Mac OS utility program Keychain Access.
In its main menu, select Keychain Access / Certificate Assistant / Request a Certificate From a Certificate Authority...
The dialog that pops up should aready have your email and name it it.
Select the radio button Saved to disk and Continue....
What are the most useful Intellij IDEA keyboard shortcuts? [closed]
...
These are some of my most used keyboard short cuts
Syntax aware selection in the editor selects a word at the caret and then selects expanding areas of the source code. For example, it may select a method name, then the expression that calls this method, then the whole statement, then the...