大约有 41,000 项符合查询结果（耗时：0.0589秒） [XML]
How to create relationships in MySQL
...s defined as the default storage engine,can check using command (mysql> SELECT @@default_storage_engine;)
– Arun
Feb 18 at 4:00
add a comment
|
...
How to empty a redis database?
...
$ redis-cli then select database. I am selecting 0 > select 0 and delete all keys of db 0 > FLUSHDB
– sagar junnarkar
May 5 '15 at 17:41
...
How do I join two SQLite tables in my Android application?
...
You need rawQuery method.
Example:
private final String MY_QUERY = "SELECT * FROM table_a a INNER JOIN table_b b ON a.id=b.other_id WHERE b.property_id=?";
db.rawQuery(MY_QUERY, new String[]{String.valueOf(propertyId)});
Use ? bindings instead of putting values into raw sql query.
...
What's the difference between NOT EXISTS vs. NOT IN vs. LEFT JOIN WHERE IS NULL?
... using Standard SQL.
An obvious omission is the equivalent using EXCEPT:
SELECT a FROM table1
EXCEPT
SELECT a FROM table2
Note in Oracle you need to use the MINUS operator (arguably a better name):
SELECT a FROM table1
MINUS
SELECT a FROM table2
Speaking of proprietary syntax, there may also ...
How I can I lazily read multiple JSON values from a file/stream in Python?
... end_pos = int(re.match('Extra data: line \d+ column \d+ .*\(char (\d+).*\)',
e.args[0]).groups()[0])
json_str = f.read(end_pos)
obj = json.loads(json_str)
start_pos += end_pos
yield obj...
Is there a python equivalent of Ruby's 'rvm'?
...
Optionally, if you're using Macports you can use python_select.
Install python_select with:
$ sudo port install python_select
Assuming python 2.6 and 2.5 have bee installed via Macports you can switch pythons like so:
$ sudo python_select python25
=> Selecting version "pyth...
postgresql COUNT(DISTINCT …) very slow
...
You can use this:
SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;
This is much faster than:
COUNT(DISTINCT column_name)
share
...
How can I pass selected row to commandLink inside dataTable or ui:repeat?
...ces in a JSF 2 application. I have a <p:dataTable> , and instead of selecting rows, I want the user to be able to directly execute various actions on individual rows. For that, I have several <p:commandLink> s in the last column.
...
Transferring an app to another Firebase account
...another account. All you have to do is:
Go to your Firebase console, and select the project you want to shift.
Select the cog icon besides the project name on top right.
Select Permissions from the flyout.
Select Advanced permission settings hyperlink.
You've reached the IAM & Admin page of Fi...
C++ templates that accept only certain types
...that the compiler allows these, and then declare a variable my_template<char> z; and verify that it doesn't.
– j_random_hacker
Nov 16 '17 at 16:20
...