I want to implement my own simple multi tasking shell in Unix which will take care of redirection (<, >, >>) and piping.
I am just unable to get a concrete idea of how exactly I have to start. I have several books...some are..
1. Maurice Bach- Design Of Unix Operating System
2. Richard... (3 Replies)
Hey Guys
I am trying to implement the malloc function for my OS class and I am having a little trouble with it. I would be really grateful if I could get some hints on this problem.
So I am using a doubly-linked list as my data structure and I have to allocate memory for it (duh...). The... (1 Reply)
Hey Guys
Some of my friends have got together and we are trying to write a basic kernel similar to Linux. I am trying to implement the malloc function in C and I am using a doubly linked list as the primary data structure. I need to allocate memory for this link list (duh...) and I don't feel... (2 Replies)
Hi all,I'm reading <Advanced programming in the UNIX environment>,that book asked the reader to implement a function which has same functions with dup2 without calling fcntl.Could anyone give me a tip?Any help will be appreciated.:) (8 Replies)
Hi
I'm trying to implement CAPWAP protocol for my application.i'm able to configure my server side but i'm getting error at client(WTP) side as IOCTL error.while running the command
#./WTP /mnt/cf/capwap/
: wlan2
Starting WTP...
# WTP Loads... (0 Replies)
Hi everybody,
i've been googling for ages now and gotten kinda desperate... The question, however, might be rather trivial for the experts: What is it exactly, i.e. physically, the POSIX function (for a file) "lseek" does? Does it trigger some kind of synchronization on disk? Is it just for the... (4 Replies)
I have this code from a programming book:
#include <stdio.h>
#include <string.h>
char buf; /* input line buffer */
char* field; /* fields */
char* unquote( char* );
/* csvgetline: read and parse line, return field count */
/* sample input:... (3 Replies)
Discussion started by: totoro125
3 Replies
LEARN ABOUT REDHAT
update
UPDATE(7) SQL Commands UPDATE(7)NAME
UPDATE - update rows of a table
SYNOPSIS
UPDATE [ ONLY ] table SET col = expression [, ...]
[ FROM fromlist ]
[ WHERE condition ]
INPUTS
table The name (optionally schema-qualified) of an existing table. If ONLY is specified, only that table is updated. If ONLY is not speci-
fied, the table and all its descendant tables (if any) are updated. * can be appended to the table name to indicate that descendant
tables are to be scanned, but in the current version, this is the default behavior. (In releases before 7.1, ONLY was the default
behavior.) The default can be altered by changing the SQL_INHERITANCE configuration option.
column The name of a column in table.
expression
A valid expression or value to assign to column.
fromlist
A PostgreSQL non-standard extension to allow columns from other tables to appear in the WHERE condition.
condition
Refer to the SELECT statement for a further description of the WHERE clause.
OUTPUTS
UPDATE #
Message returned if successful. The # means the number of rows updated. If # is 0 no rows are updated.
DESCRIPTION
UPDATE changes the values of the columns specified for all rows which satisfy condition. Only the columns to be modified need appear as
columns in the statement.
Array references use the same syntax found in SELECT [select(7)]. That is, either single array elements, a range of array elements or the
entire array may be replaced with a single query.
You must have write access to the table in order to modify it, as well as read access to any table whose values are mentioned in the WHERE
condition.
By default UPDATE will update tuples in the table specified and all its sub-tables. If you wish to only update the specific table men-
tioned, you should use the ONLY clause.
USAGE
Change word Drama with Dramatic on column kind:
UPDATE films
SET kind = 'Dramatic'
WHERE kind = 'Drama';
SELECT *
FROM films
WHERE kind = 'Dramatic' OR kind = 'Drama';
code | title | did | date_prod | kind | len
-------+---------------+-----+------------+----------+-------
BL101 | The Third Man | 101 | 1949-12-23 | Dramatic | 01:44
P_302 | Becket | 103 | 1964-02-03 | Dramatic | 02:28
M_401 | War and Peace | 104 | 1967-02-12 | Dramatic | 05:57
T_601 | Yojimbo | 106 | 1961-06-16 | Dramatic | 01:50
DA101 | Das Boot | 110 | 1981-11-11 | Dramatic | 02:29
COMPATIBILITY
SQL92
SQL92 defines a different syntax for the positioned UPDATE statement:
UPDATE table SET column = expression [, ...]
WHERE CURRENT OF cursor
where cursor identifies an open cursor.
SQL - Language Statements 2002-11-22 UPDATE(7)