I would like to have access to the Seconds_Behind_Master field, (as returned by SHOW SLAVE STATUS) from inside a stored procedure.
I can't figure out how to get its value inside a variable. None of the usual SET/SELECT syntax seems to work.
Is there a way to do that?
Just for the record: it has turned out to be possible to open a cursor for SHOW statements. This allows to parse the output and work with it inside a stored procedure.
From what I see in the recent docs and MySQL Bug#37187 there does not seem to be any way but SHOW SLAVE STATUS to get to this information.
PHP can grab all the fields of the show slave status into a hashmap, like this:
$db = new pdo(
"mysql:host=your_database_hostname;dbname=your_database_name",
'your_username', 'your_password');
$sql = 'show slave status';
$query = $db->query($sql);
$res = $query->fetchall();
foreach($res as $item){
print ">" . $item["Seconds_Behind_Master"];
}
Which prints 0 seconds because everything is up to date:
>0
I tried for an hour to create a stored procedure to do this. I recommend you don't waste your time.
Related
I've searched high and low for an answer on this, but I'm either missing something, or I just can't find anything in this context.
Background - trying to avoid spaghetti frenzy with a little casual project I'm starting; part of this will involve mainly just calls to a mysql database, displaying table content and so on. Simply put, like a CRM I guess.
I may be way off base here, but I want to be able to create my sql calls as functions, which will help if/when I tweak and tune, as well as creating a cleaner code for what I'm looking to do.
So, without further ado, I have this as a demomstration:
echo "<table>";
selectall('actions','content',$mysqli);
echo "</table><br><br>";
What this does is show all rows from my table of 'actions. "content" is just an example field name I'm passing through that I want to display, as it is the main human-relevant field name in that table. I'm also passing $mysqli through here for my function db call.
My function looks like this:
function selectall($s_table,$s_content,$mysqli){
$query = "SELECT * FROM " . $s_table;
$resource = $mysqli->query($query);
if ( !$resource ) throw new Exception($db->error);
while ( $row = $resource->fetch_assoc() ) {
$id = $row['id'];
echo "<tr><td>{$row[$s_content]}</td></tr>";
}
$resource->free();
$mysqli->close();
}
However.... it doesn't work, and it seems to throw a wobbly saying:
Warning: mysqli::query(): Couldn't fetch mysqli
This points to the action within the line $resource = $mysqli->query($query);
I know the function and everything is ok, as if I restate and declare $mysqli within the first line of the function, like so...
$mysqli = new mysqli(username password and so on in here);
... it works spot on.
$mysqli exists and works within the same code that is passing the variable within the function too.
This is early stages, so by shuffling the code around trying to poke the $mysqli pass into life I have perhaps made the code a little messier that intended, so try not to worry too much about that.
Anyone any ideas why it doesn't like this?
D'oh...
I had a
$mysqli->close();
in the lines above. Solved myself.
For reference, this is my function:
function selectall($s_table,$s_field,$mysqli){
if ($mysqli->connect_error) {die('Connect Error (' . $mysqli->connect_errno . ') '. $mysqli->connect_error);}
$s_table = preg_replace('/[^0-9a-zA-Z_]/', '', $s_table); // Cleans up the table name variable
$s_field = preg_replace('/[^0-9a-zA-Z_]/', '', $s_field); // Cleans up the field name variable
$query = "SELECT * FROM " . $s_table; // Adds passed table name to the select all
$resource = $mysqli->query($query);
if ( !$resource ) throw new Exception($db->error);
while ( $row = $resource->fetch_assoc() ) {
echo "<tr><td>{$row[$s_field]}</td></tr>"; // Content for each row of the select all
}
$resource->free();
$mysqli->close();
}
As you can see, I've also tried to protect the variables that enter the function.
This can be called via:
selectall('actions','content',$mysqli);
In this context, I want to view all the entries in the 'actions' table by the field name 'content'. This function, with some code above and below for a table, will create a new row for each entry.
I'll probably evolve a few, already created on that includes a delete button at the end of the line which is 'selectalldel'.
Open to comments on whether this actually is worthwhile, but thought I'd post up my corrected stupidity in case anyone finds this useful.
I am running into an issue trying to use a list in with orasql. Is there another way to do it? I know I could loop through using foreach and set the value to a string variable but I think it would take a lot longer with all of those little db pulls. I could also run one query but I am no DBM and I can't seem to get the query time down, it's a lot more complex than what I am laying out here and I need users to pull it as quickly as possible.
How can I do something like this:
orasql $DB(db) "select this from this_table"
orafetch $DB(db) {
lappend list1 #1
}
orasql $DB(db) "select that from that_table where this in ($list1)"
orafetch $DB(db) {
lappend that #1
}
Is this what you are trying to do?
select that
from that_table
where this in (select this from this_table);
I wrote a Perl script to check the data in an Oracle database. Because the query process is very complex I chose to create a VIEW in the middle. Using this view the code could be largely simplified.
The Perl code run well when I used it to query the database starting from a file, like Perl mycode.pl file_a. The Perl code reads lines from file_a and creates/updates the view until the end of the input. The results I achieved are completely right.
The problem came when I simultaneously run
perl mycode.pl file_a
and
perl mycode.pl file_b
to access the same database. According to my observation, the VIEW used by the first process will be modified by the second process. These two processes were intertwined on the same view.
Is there any suggestion to make these two processes not conflict with one another?
The Perl code for querying database is normally like this, but the details in each real query is more complex.
my ($gcsta,$gcsto,$cms) = #t; #(details of #t is read from a line in file a or b)
my $VIEWSS = 'CREATE OR REPLACE VIEW VIEWSS AS SELECT ID,GSTA,GSTO,GWTA FROM TABLEA WHERE GSTA='.$gcsta.' AND GSTO='.$gcsto.' AND CMS='.$cms;
my $querying = q{ SELECT COUNT(*) FROM VIEWSS WHERE VIEWSS.ID=1};
my $inner_sth = $dbh->prepare($VIEWSS);
my $inner_rv = $inner_sth->execute();
$inner_sth = $dbh->prepare($querying);
$inner_rv = $inner_sth->execute();
You must
Create the view only once, and use it everywhere
Use placeholders in your SQL statements, and pass the actual parameters with the call to execute
Is this the full extent of your SQL? Probably not, but if so it really is fairly simple.
Take a look at this refactoring for some ideas. Note that is uses a here document to express the SQL. The END_SQL marker for the end of the text must have no whitespace before or after it.
If your requirement is more complex than this then please describe it to us so that we can better help you
my $stmt = $dbh->prepare(<<'END_SQL');
SELECT count(*)
FROM tablea
WHERE gsta = ? AND gsto = ? AND cms= ? AND id = 1
END_SQL
my $rv = $stmt->execute($gcsta, $gcsto, $cms);
If you must use a view then you should use placeholders in the CREATE VIEW as before, and make every set of changes into a transaction so that other processes can't interfere. This involves disabling AutoCommit when you create the database handle $dbh and adding a call to $dbh->commit when all the steps are complete
use strict;
use warnings;
use DBI;
my $dbh = DBI->connect('dbi:Oracle:mydbase', 'user', 'pass',
{ AutoCommit => 0, RaiseError => 1 } );
my $make_view = $dbh->prepare(<<'END_SQL');
CREATE OR REPLACE VIEW viewss AS
SELECT id, gsta, gsto, gwta
FROM tablea
WHERE gsta = ? AND gsto = ? AND cms= ? AND id = 1
END_SQL
my $get_count = $dbh->prepare(<<'END_SQL');
SELECT count(*)
FROM viewss
WHERE id = 1
END_SQL
while (<>) {
my ($gcsta, $gcsto, $cms) = split;
my $rv = $make_view->execute($gcsta, $gcsto, $cms);
$rv = $get_count->execute;
my ($count) = $get_count->fetchrow_array;
$dbh->commit;
}
Is the view going to be the same or different?
If the views are all the same then create it only once, or check if it exists with the all_views table : http://docs.oracle.com/cd/B12037_01/server.101/b10755/statviews_1202.htm#i1593583
You can easily create a view including your pid with the $$ variable to be the pid, but it wont be unique across computers, oracle has also some unique ids, see http://docs.oracle.com/cd/B14117_01/server.101/b10759/functions150.htm, for example, the SESSIONID.
But do you really need to do this? why dont you prepare a statement and then execute it? http://search.cpan.org/dist/DBI/DBI.pm#prepare
thanks,
mike
I am trying to retrieve data from a simple mySql table tbl_u_type which has just two columns, 'tid' and 'type'.
I want to use a direct SQL query instead of the Model logic. I used:
$command = Yii::app()->db->createCommand();
$userArray = $command->select('type')->from('tbl_u_type')->queryAll();
return $userArray;
But in the dropdown list it automatically shows an index number along with the required entry. Is there any way I can avoid the index number?
To make an array of data usable in a dropdown, use the CHtml::listData() method. If I understand the question right, this should get you going. Something like this:
$command = Yii::app()->db->createCommand();
$userArray = $command->select('tid, type')->from('tbl_u_type')->queryAll();
echo CHtml::dropdownlist('my_dropdown','',CHtml::listData($userArray,'tid','type'));
You can also do this with the Model if you have one set up for the tbl_u_type table:
$users = UType::model()->findall();
echo CHtml::dropdownlist('my_dropdown','',CHtml::listData($users ,'tid','type'));
I hope that gets you on the right track. I didn't test my code here, as usual, so watch out for that. ;) Good luck!
I have a weird problem, when i use the query on phpmyadmin, it works. but when i use using a php script it returns an error.
Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in
I tried to troubleshoot and discovered that the problem lies with the set statement.
this is my example code.
$sql = 'set #rank=0; select * from user;';
Please help somebody.
First Run
$sql = set #rank=0;
it will store value of rank
then run:
select * from user;
In sort you need to run both queries separately .
set statement stores values. that can be used by next executing query,
like code below :
$sql ="SET #id:=0";
$Executives=$DB->exec($sql);
$sql = "SELECT #id:=#id+1 as id,pes.* FROM profile_executive_summary as pes where profile_id=".$pid;
$Executives=$DB->fetchAssoc($sql);
See what mysql_error returns after you run mysql_query('...'). That might help. In general, mysql_query only permits one query. You can't separate them by newlines or semicolons. mysqli will do it for you though.