query(" SHOW TABLES ") or die($mysqli->error);

while ($row_tables = $rs_tables->fetch_row()) {
$table = $mysqli->real_escape_string($row_tables[0]);

// Alter table collation
// ALTER TABLE `account` DEFAULT CHARACTER SET utf8
if ($show_alter_table)
echo("ALTER TABLE `$table` DEFAULT CHARACTER SET $character_set;\n");

$rs = $mysqli->query(" SHOW FULL FIELDS FROM `$table` ") or die($mysqli->error);

while ($row = $rs->fetch_assoc()) {

if ($row['Collation'] == '' || $row['Collation'] == $convert_to)
continue;

// Is the field allowed to be null?
if ($row['Null'] == 'YES')
$nullable = ' NULL ';
else
$nullable = ' NOT NULL ';

// Does the field default to null, a string, or nothing?
if ($row['Default'] === null && $row['Null'] == 'YES')
$default = " DEFAULT NULL ";
elseif ($row['Default'] != '')
$default = " DEFAULT '" . $mysqli->real_escape_string($row['Default']) . "'";
else
$default = '';

// sanity check and fix:
if ($nullable == ' NOT NULL ' && $default == ' DEFAULT NULL ') {
$default = '';
echo "/* Warning: wrong combination of 'default value' and 'NULL-flag' detected - and fixed! */\n";
echo "/* Diagnostics: row[Null] = '$row[Null]', row[Default] = " . $mysqli->real_escape_string($row['Default']) . ", MySQL version: " . $mysqli->get_server_info() . " */\n";
}

// Don't alter INT columns: no collations, and altering them drops autoincrement values
if (strpos($row['Type'], 'int') !== false) {
$show_alter_field = false;
} else {
$show_alter_field = true;
}

// Alter field collation:
// ALTER TABLE `tab` CHANGE `field` `field` CHAR( 5 ) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL
if ($show_alter_field) {
$field = $mysqli->real_escape_string($row['Field']);
echo "ALTER TABLE `$table` CHANGE `$field` `$field` $row[Type] CHARACTER SET $character_set COLLATE $convert_to $nullable $default;\n";
}
}
}


By the way, technically the latest script version is _only_ about 5 years old – but yeah, that’s surprisingly long anyway in the modern age of permanent change

to copy-paste: first click the “Plain text” header”

If there is no Collation for a field, then there is nothing to change – this script will do nothing as well.

i want to ask you please :
i have afield on my database that not have colaction , and it wan’t to change to utf8 (by phpmyadmin ) , is your script force it to change ?

thank you

copy-paste the script into a PHP file on your web-hosting/server (e.g. “convert.php”).
Then access the script with your browser (http://your-domain-here/path-to/convert.php), follow the instruction for DB backup and code line removal.
You will get a set of SQL statements which you can then copy-paste into your DB admin tool (most commonly phpMyAdmin).

Alternatively, you can run this script from the command line (e.g. using php-cli) directly on the server.

thank you

David

the script does not modify the database – this is a precaution.
You have to run these queries yourself.
This is to ensure that you take full responsibility for your actions, and have all the backups you need.

You may use phpmyadmin to run those queries.

I am using MODx CMS and needed such a script to alter my collation to utf8

The script ran pretty well and here is a short snippet I got on my screen:

ALTER TABLE `sitename_access_actiondom` DEFAULT CHARACTER SET utf8;
ALTER TABLE `sitename_access_actiondom` CHANGE `target` `target` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ;
ALTER TABLE `sitename_access_actiondom` CHANGE `principal_class` `principal_class` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL DEFAULT 'modPrincipal';
ALTER TABLE `sitename_access_actions` DEFAULT CHARACTER SET utf8;
ALTER TABLE `sitename_access_actions` CHANGE `target` `target` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ;
ALTER TABLE `sitename_access_actions` CHANGE `principal_class` `principal_class` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL DEFAULT 'modPrincipal';
.............


I checked my db in phpMyAdmin and still, all fields' collation have 'latin1_swedish_ci'

What am i missing here?

I was wondering if the generated SQL could be optimized, by grouping the changes for multiple columns to convert in a given table, into a single ALTER TABLE statement.

Yes, it could be done. Looks like the only change needed is merging and comma-separating all the CHANGE statements (according to mysql refman).

I’ll consider implementing this performance improvement soon.

Many thanks for your useful script, it has done a perfect job in converting my database from latin1_swedish_ci to utf8_general_ci.

I was wondering if the generated SQL could be optimized, by grouping the changes for multiple columns to convert in a given table, into a single ALTER TABLE statement.

The reason I’m asking you this, is that in the DB I just converted there is a large MyISAM table containing a BLOB (1.2 GB data file) as well as 6 varchar columns. Your script generated 7 distinct ALTER TABLE statements (one for the table, plus one for each column to convert), which ran in 8’20, 4’15, 3’52, 4’22, 6’33, 5’10 and 5’11 respectively.

Thanks again.

Hopefully, this is the last fix for this annoying problem.

SQL query:

ALTER TABLE `agenda_categorie` CHANGE `titre` `titre` varchar( 225 ) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT NULL ;

MySQL said: Documentation
#1067 – Invalid default value for ‘titre’

help plz!!!