10 More Discussions You Might Find Interesting
1. UNIX for Beginners Questions & Answers
Hi
I'm using the "select" command in the global_env.sh to log in to the application directory. This file is called in .bashrc profile.
Sample code:
Filename: global_env.sh
set -o vi
export severname=$(uname -n)
printf '%s\n%30s\n%s\n' "***********************" "Welcome to $severname"... (6 Replies)
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2. Programming
I have created two sockets and binded both. My requirement is that 2nd socket must send/ recv data only on expiration of timeval(tv). but the 1st socket must keep on send/recv the data without waiting for the 2nd socket completion......
I have posted my code below......
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3. Boot Loaders
Hello,
I have kubuntu on my laptop and now I decided to switch to Windows 7. I made the bios settings properly (first choice is boot from cd\vd) but I see the error
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4. Programming
Is select only supposed to report state changes on an FD's, state, whether or not it had pending input available in the first place? I've got a situation where select() repeatedly reports no FD's ready for stdin when there's lots of data available. And if it only reports changes, how is this... (2 Replies)
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5. Shell Programming and Scripting
Hi I have i doubt, actually i have to select everything before a word(pattern).For that i am using sed
i am using the below line of code but it is not working i am getting a blank instead..
sed -n '/regexp/{g;1!p;};h' file1
Can anyone help?
Thanks (15 Replies)
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6. Shell Programming and Scripting
I've a file like this:
andrea andre@lol.com october
antonio@lol.com
marco 45247@pop.com
kk@pop.com may
pollo@lol.com
mary mary@lol.com
can I select only the column with email adress?
can I utilise a filter with @ ?
I want obtain this:
... (2 Replies)
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7. UNIX for Advanced & Expert Users
Please provide the solution for the following scenario:
1) There are two process named as ProcessA and ProcessB
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8. Shell Programming and Scripting
We are using the line #!/usr/bin/ksh in the script, to run the script in ksh. If I have Bash shell and Ksh, how to select the shell to run the script during runtime?
Thanks in advace
Victor (2 Replies)
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9. IP Networking
Hi,
Off late I had been looking at the differences b/w select() & poll() system calls. The requirement is to reduce the overhead, processor power in waiting for the data. In the kind of connections under consideration there would be very frequent data arriving on the sockets, so poll() fares... (12 Replies)
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10. UNIX for Dummies Questions & Answers
Hi all,
How can i select all and copy text in VI Editor.
Rakesh Gupta (22 Replies)
Discussion started by: rakish
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DBIx::Class::SQLMaker::LimitDialects(3) User Contributed Perl Documentation DBIx::Class::SQLMaker::LimitDialects(3)
NAME
DBIx::Class::SQLMaker::LimitDialects - SQL::Abstract::Limit-like functionality for DBIx::Class::SQLMaker
DESCRIPTION
This module replicates a lot of the functionality originally found in SQL::Abstract::Limit. While simple limits would work as-is, the more
complex dialects that require e.g. subqueries could not be reliably implemented without taking full advantage of the metadata locked within
DBIx::Class::ResultSource classes. After reimplementation of close to 80% of the SQL::Abstract::Limit functionality it was deemed more
practical to simply make an independent DBIx::Class-specific limit-dialect provider.
SQL LIMIT DIALECTS
Note that the actual implementations listed below never use "*" literally. Instead proper re-aliasing of selectors and order criteria is
done, so that the limit dialect are safe to use on joined resultsets with clashing column names.
Currently the provided dialects are:
LimitOffset
SELECT ... LIMIT $limit OFFSET $offset
Supported by PostgreSQL and SQLite
LimitXY
SELECT ... LIMIT $offset $limit
Supported by MySQL and any SQL::Statement based DBD
RowNumberOver
SELECT * FROM (
SELECT *, ROW_NUMBER() OVER( ORDER BY ... ) AS RNO__ROW__INDEX FROM (
SELECT ...
)
) WHERE RNO__ROW__INDEX BETWEEN ($offset+1) AND ($limit+$offset)
ANSI standard Limit/Offset implementation. Supported by DB2 and MSSQL >= 2005.
SkipFirst
SELECT SKIP $offset FIRST $limit * FROM ...
Suported by Informix, almost like LimitOffset. According to SQL::Abstract::Limit "... SKIP $offset LIMIT $limit ..." is also supported.
FirstSkip
SELECT FIRST $limit SKIP $offset * FROM ...
Supported by Firebird/Interbase, reverse of SkipFirst. According to SQL::Abstract::Limit "... ROWS $limit TO $offset ..." is also
supported.
RowNum
Depending on the resultset attributes one of:
SELECT * FROM (
SELECT *, ROWNUM rownum__index FROM (
SELECT ...
) WHERE ROWNUM <= ($limit+$offset)
) WHERE rownum__index >= ($offset+1)
or
SELECT * FROM (
SELECT *, ROWNUM rownum__index FROM (
SELECT ...
)
) WHERE rownum__index BETWEEN ($offset+1) AND ($limit+$offset)
or
SELECT * FROM (
SELECT ...
) WHERE ROWNUM <= ($limit+1)
Supported by Oracle.
Top
SELECT * FROM
SELECT TOP $limit FROM (
SELECT TOP $limit FROM (
SELECT TOP ($limit+$offset) ...
) ORDER BY $reversed_original_order
) ORDER BY $original_order
Unreliable Top-based implementation, supported by MSSQL < 2005.
CAVEAT
Due to its implementation, this limit dialect returns incorrect results when $limit+$offset > total amount of rows in the resultset.
FetchFirst
SELECT * FROM
(
SELECT * FROM (
SELECT * FROM (
SELECT * FROM ...
) ORDER BY $reversed_original_order
FETCH FIRST $limit ROWS ONLY
) ORDER BY $original_order
FETCH FIRST $limit ROWS ONLY
)
Unreliable FetchFirst-based implementation, supported by IBM DB2 <= V5R3.
CAVEAT
Due to its implementation, this limit dialect returns incorrect results when $limit+$offset > total amount of rows in the resultset.
GenericSubQ
SELECT * FROM (
SELECT ...
)
WHERE (
SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id
) BETWEEN $offset AND ($offset+$rows-1)
This is the most evil limit "dialect" (more of a hack) for really stupid databases. It works by ordering the set by some unique column, and
calculating the amount of rows that have a less-er value (thus emulating a "RowNum"-like index). Of course this implies the set can only be
ordered by a single unique column.
Also note that this technique can be and often is excruciatingly slow. You may have much better luck using "software_limit" in
DBIx::Class::ResultSet instead.
Currently used by Sybase ASE, due to lack of any other option.
AUTHORS
See "CONTRIBUTORS" in DBIx::Class.
LICENSE
You may distribute this code under the same terms as Perl itself.
perl v5.18.2 2014-01-22 DBIx::Class::SQLMaker::LimitDialects(3)