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Dynamic Sorting within SQL Stored Procedures
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This approach keeps the sortable columns from being duplicated twice in the order by, and is a little more readable IMO:
SELECT
s.*
FROM
(SELECT
CASE @SortCol1
WHEN 'Foo' THEN t.Foo
WHEN 'Bar' THEN t.Bar
ELSE null
END as ...
如何查看Oracle用户的SQL执行历史记录？ - 数据库(内核) - 清泛网 - 专注C/...
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SQL> select username,scn,timestamp,sql_redo from v$logmnr_contents where table_name='TEST2';
SQL> select username,scn,timestamp,sql_redo from v$logmnr_contents where username='P_CHENMING';
--关闭MINER
SQL> execute dbms_logmnr.end_logmnr;
--关闭辅助日志
SQL> alter database drop suppl...
SQL JOIN vs IN performance?
... faster more often than not.
So if you are only interested in values from table a you can use this query:
SELECT a.*
FROM a
WHERE EXISTS (
SELECT *
FROM b
WHERE b.col = a.col
)
The difference might be huge if col is not indexed, because the db does not have to find al...
How to show multiline text in a table cell
I want to show a paragraph from database into a table cell.
10 Answers
10
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Python's json module, converts int dictionary keys to strings
...e.
In Python (and apparently in Lua) the keys to a mapping (dictionary or table, respectively) are object references. In Python they must be immutable types, or they must be objects which implement a __hash__ method. (The Lua docs suggest that it automatically uses the object's ID as a hash/key ...
Difference between 3NF and BCNF in simple terms (must be able to explain to an 8-year old)
...hree topping types:
one type of cheese
one type of meat
one type of vegetable
So we order two pizzas and choose the following toppings:
Pizza Topping Topping Type
-------- ---------- -------------
1 mozzarella cheese
1 pepperoni meat
1 olives vegetable
2 ...
How to show the last queries executed on MySQL?
...ontrol this option globally at runtime:
Execute SET GLOBAL log_output = 'TABLE';
Execute SET GLOBAL general_log = 'ON';
Take a look at the table mysql.general_log
If you prefer to output to a file instead of a table:
SET GLOBAL log_output = "FILE"; the default.
SET GLOBAL general_log_file = ...
How to list all users in a Linux group?
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Unfortunately, there is no good, portable way to do this that I know of. If you attempt to parse /etc/group, as others are suggesting, you will miss users who have that group as their primary group and anyone who has been added to that group via a mechanism ot...
iOS 7 - How to display a date picker in place in a table view?
In WWDC 2013 video, Apple suggests displaying picker in place in a table view in iOS 7. How to insert and animate a view between table view cells?
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Change a column type from Date to DateTime during ROR migration
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First in your terminal:
rails g migration change_date_format_in_my_table
Then in your migration file:
For Rails >= 3.2:
class ChangeDateFormatInMyTable < ActiveRecord::Migration
def up
change_column :my_table, :my_column, :datetime
end
def down
change_column :my_tabl...