大约有 48,000 项符合查询结果（耗时：0.0262秒） [XML]
SQL to find the number of distinct values in a column
I can select all the distinct values in a column in the following ways:
11 Answers
11
...
Copy/duplicate database without using mysqldump
...the references, you can run the following to copy the data:
INSERT INTO x SELECT * FROM other_db.y;
If you're using MyISAM, you're better off to copy the table files; it'll be much faster. You should be able to do the same if you're using INNODB with per table table spaces.
If you do end up doin...
java.sql.SQLException: - ORA-01000: maximum open cursors exceeded
... a query, specifically the position where a reader is in a ResultSet. Each SELECT statement has a cursor, and PL/SQL stored procedures can open and use as many cursors as they require. You can find out more about cursors on Orafaq.
A database instance typically serves several different schemas, man...
Read data from SqlDataReader
...you use indexes like reader.GetString(0) will it use the first column you selected in your query or the firstt column on the table. I have a table with 3 columns in order: ID, Dir, Email. My command selects dir and email. Will reader.GetStrting(0) retrieve dir or ID? Are the indexes based off t...
How enumerate all classes with custom class attribute?
... faster (especially without empirical proof); you've basically written the Select extension method, and the compiler will generate a state machine just as it would if you called Select because of your use of yield return. Finally, any performance gains that might be obtained in the majority of case...
powershell - extract file name and extension
...tated, use the BaseName and Extension properties:
PS C:\> dir *.xlsx | select BaseName,Extension
BaseName Extension
-------- ---------
StackOverflow.com Test Config .xlsx
If you are given the file name as part of string...
Inefficient jQuery usage warnings in PHPStorm IDE
...o find a solution thanks to Scott Kosman here.
Basically the answer is to select IDs individually and then use .find(...) for anything below. So taking your example:
$("#property [data-role='content'] .container");
Changing it to this makes PhpStorm happy and can evidently be more than twice as ...
How to convert all tables from MyISAM into InnoDB?
...database here first
//
// Actual code starts here
$sql = "SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'your_database_name'
AND ENGINE = 'MyISAM'";
$rs = mysql_query($sql);
while($row = mysql_fetch_array($rs))
{
$tbl = ...
Rename a class in Xcode: Refactor… is grayed out (disabled). Why?
...
Select the class's symbol in its header file - i.e. the bit just after @interface. Then the refactoring stuff should be enabled.
share
|
...
How to remove selected commit log entries from a Git repository while keeping their changes?
I would like to remove selected commit log entries from a linear commit tree, so that the entries do not show in the commit log.
...