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Why would you use an ivar?
... in the implementations of an accessor, a convenience constructor, copy, mutableCopy, and archiving/serialization implementations.
It's also more frequent as one moves from the everything has a public readwrite accessor mindset to one which hides its implementation details/data well. Sometimes you n...
MySQL Delete all rows from table and reset ID to zero
I need to delete all rows from a table but when I add a new row, I want the primary key ID, which has an auto increment, to start again from 0 respectively from 1.
...
The tilde operator in Python
...se complement operator in python which essentially calculates -x - 1
So a table would look like
i ~i
0 -1
1 -2
2 -3
3 -4
4 -5
5 -6
So for i = 0 it would compare s[0] with s[len(s) - 1], for i = 1, s[1] with s[len(s) - 2].
As for your other question, this can be useful for a range of ...
brew install mysql on macOS
... like there is something wrong with the set up instructions or the initial tables that are being created. This is how I got mysqld running on my machine.
If the mysqld server is already running on your Mac, stop it first with:
launchctl unload -w ~/Library/LaunchAgents/com.mysql.mysqld.plist
Star...
MySQL: How to copy rows, but change a few fields?
...
INSERT INTO Table
( Event_ID
, col2
...
)
SELECT "155"
, col2
...
FROM Table WHERE Event_ID = "120"
Here, the col2, ... represent the remaining columns (the ones ...
Host 'xxx.xx.xxx.xxx' is not allowed to connect to this MySQL server
...you cannot figure out why you get
Access denied, remove from the user
table all entries that have Host
values containing wildcards (entries
that contain '%' or '_' characters). A
very common error is to insert a new
entry with Host='%' and
User='some_user', thinking that this
allows...
Regex to Match Symbols: !$%^&*()_+|~-=`{}[]:";'?,./
...rs can't be represented more simply with a range: !"^_`[].
Use an ACSII table to find ranges for character classes.
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How can I get the list of a columns in a table for a SQLite database?
I am looking to retrieve a list of columns in a table. The database is the latest release of SQLite (3.6, I believe). I am looking for code that does this with a SQL query. Extra bonus points for metadata related to the columns (e.g. length, data type, etc...)
...
Why isn't sizeof for a struct equal to the sum of sizeof of each member?
...mbers-order-guarantee in C++. Compilers may (and certainly do) add virtual table pointer and base structures' members to the structure. Even the existence of virtual table is not ensured by the standard (virtual mechanism implementation is not specified) and therefore one can conclude that such guar...
How do you create a read-only user in PostgreSQL?
...
Grant usage/select to a single table
If you only grant CONNECT to a database, the user can connect but has no other privileges. You have to grant USAGE on namespaces (schemas) and SELECT on tables and views individually like so:
GRANT CONNECT ON DATABASE...