大约有 40,000 项符合查询结果（耗时：0.0502秒） [XML]
What is the difference between ExecuteScalar, ExecuteReader and ExecuteNonQuery?
... then the result is the first column of the first row. An example might be SELECT @@IDENTITY AS 'Identity'.
ExecuteReader is used for any result set with multiple rows/columns (e.g., SELECT col1, col2 from sometable).
ExecuteNonQuery is typically used for SQL statements without results (e.g., UPDATE...
ADB not recognising Nexus 4 under Windows 7
...nstall the generic 'MTP device driver'
Right clicked on the new device and selected 'Update Driver'
Selected 'Have Disk' and pointed it to [android-sdk-dir]\extras\google
Watched an 'ADB' driver install.
Opened Eclipse to successfully run on my Nexus 4.
Good luck!
...
The object cannot be deleted because it was not found in the ObjectStateManager
... var project = context.Projects
.Include(p => p.Reports.Select(q => q.Issues.Select(r => r.Profession)))
.Include(p => p.Reports.Select(q => q.Issues.Select(r => r.Room)))
.SingleOrDefault(x => x.Id == id);
return proje...
MySQL with Node.js
....log('connected as id ' + connection.threadId);
connection.query("select * from user",function(err,rows){
connection.release();
if(!err) {
res.json(rows);
}
});
connection.on('error', function(err) {
...
PostgreSQL “DESCRIBE TABLE”
... 'table' or \ds 'sequence' and so on)
The SQL standard way, as shown here:
select column_name, data_type, character_maximum_length, column_default, is_nullable
from INFORMATION_SCHEMA.COLUMNS where table_name = '<name of table>';
It's supported by many db engines.
...
How do you list the primary key of a SQL Server table?
...
SELECT Col.Column_Name from
INFORMATION_SCHEMA.TABLE_CONSTRAINTS Tab,
INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE Col
WHERE
Col.Constraint_Name = Tab.Constraint_Name
AND Col.Table_Name = Tab.Table_Name
...
How do you return the column names of a table?
...
Not sure if there is an easier way in 2008 version.
USE [Database Name]
SELECT COLUMN_NAME,*
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'YourTableName' AND TABLE_SCHEMA='YourSchemaName'
share
|
...
How to take all but the last element in a sequence using LINQ?
...eq = Enumerable.Range(1, 10);
Console.WriteLine(string.Join(", ", Seq.Select(x => x.ToString()).ToArray()));
Console.WriteLine(string.Join(", ", Seq.TakeAllButLast().Select(x => x.ToString()).ToArray()));
}
Or as a generalized solution discarding the last n items (using a queue like...
MySQL COUNT DISTINCT
...
Select
Count(Distinct user_id) As countUsers
, Count(site_id) As countVisits
, site_id As site
From cp_visits
Where ts >= DATE_SUB(NOW(), INTERVAL 1 DAY)
Group By site_id
...
Values of disabled inputs will not be submitted
...lements support the disabled attribute: BUTTON, INPUT,
OPTGROUP, OPTION, SELECT, and TEXTAREA.
This attribute is inherited but local declarations override the
inherited value.
How disabled elements are rendered depends on the user agent. For
example, some user agents "gray out" disab...