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Get record counts for all tables in MySQL database
...ount FROM my_schema.host UNION
SELECT "ndb_binlog_index" AS table_name, COUNT(*) AS exact_row_count FROM my_schema.ndb_binlog_index UNION
Copy and paste except for the last UNION to get nice output like,
+------------------+-----------------+
| table_name | exact_r...
Random record in ActiveRecord
...that using offset is very slow with large dataset, since it actually needs index scan (or table scan, in case clustered index is used like InnoDB). In other words, it's O(N) operation but "WHERE id >= #{rand_id} ORDER BY id ASC LIMIT 1" is O(log N), which is much faster.
– k...
SQL “select where not in subquery” returns no results
...mortech's answer and @rexem's comments.
If either Table1 or Table2 is not indexed on commonID, you get a table scan but @patmortech's query is still twice as fast (for a 100K row master table).
If neither are indexed on commonID, you get two table scans and the difference is negligible.
If both a...
Change type of varchar field to integer: “cannot be cast automatically to type integer”
...f the error still occurs, then it may be related not to column values, but indexes over this column or column default values might fail typecast. Indexes need to be dropped before ALTER COLUMN and recreated after. Default values should be changed appropriately.
...
Left-pad printf with spaces
...
And, to address the last part of the Q: yes, if you want each line of the data to be printed with 40 leading spaces, then you do need to segment the data so that each line is printed separately.
– Jonathan Leffler
Nov 16 '0...
How to move a git repository into another directory and make that directory a git repository?
...ry and anything git from it
$ rm -rf gitrepo1/.git
Note that the copy is quite expensive if the repository is large and with a long history. You can avoid it easily too:
# move the directory instead
$ mv gitrepo1 newrepo
# make a copy of the latest version
# Either:
$ mkdir gitrepo1; cp -r newre...
How to make a HTML Page in A4 paper size page(s)?
... is not valid CSS3, which is indeed correct — I merely repeated the code quoted in the article which (as noted) was good old CSS2 (which makes sense when you look at the year the article and this answer were first published). Anyway, here's the valid CSS3 code for your copy-and-paste convenience:
...
How to force file download with PHP
...
Display your file first and set its value into url.
index.php
<a href="download.php?download='.$row['file'].'" title="Download File">
download.php
<?php
/*db connectors*/
include('dbconfig.php');
/*function to set your files*/
function output_file($file, $name, $...
Why exactly is eval evil?
...PPLY - call a function with a list as the arguments: (apply '+ '(1 2 3)).
Q: do I really need eval or does the compiler/evaluator already what I really want?
The main reasons to avoid EVAL for slightly more advanced users:
you want to make sure that your code is compiled, because the compiler can ...
Create subdomains on the fly with .htaccess (PHP)
...riteEngine on
RewriteCond %{HTTP_HOST} ^[^.]+\.example\.com$
RewriteRule !^index\.php$ index.php [L]
Inside the index.php you can than extract the subdomain using:
if (preg_match('/^([^.]+)\.example\.com$/', $_SERVER['HTTP_HOST'], $match)) {
var_dump($match[1]);
}
But all this requires that...