{"id":151,"date":"2014-11-13T16:25:29","date_gmt":"2014-11-13T15:25:29","guid":{"rendered":"http:\/\/www.olivierdoucet.info\/blog\/?p=151"},"modified":"2014-11-13T16:34:50","modified_gmt":"2014-11-13T15:34:50","slug":"mysql-select-query-case-sensitive","status":"publish","type":"post","link":"https:\/\/www.olivierdoucet.info\/blog\/2014\/11\/13\/mysql-select-query-case-sensitive\/","title":{"rendered":"MySQL SELECT query with LIKE case sensitive ?"},"content":{"rendered":"

Today at work I helped an intern with an interesting problem I would like to share.
\nhe was doing this kind of query on a MySQL server :<\/p>\n

SELECT description FROM service WHERE description LIKE '%cloud%';<\/pre>\n
It returned these lines :<\/p>\n
cloud customer 1\r\ncloud customer 2<\/pre>\n
but does not return these two lines he\u00a0was expecting :<\/p>\n
new Cloud infra\r\nCloud customer 2<\/pre>\n
LIKE should be case insensitive … What was wrong ?<\/p>\n
<\/p>\n
Just check the create table :<\/p>\n
CREATE TABLE `service` (\r\n `id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,\r\n `description` varchar(255) CHARACTER SET utf8 utf8_bin NULL,\r\n PRIMARY KEY (`id`)\r\n) ENGINE=InnoDB;<\/pre>\n
So the field ‘description’ is considered a binary string (noticed the ‘_bin’ in utf8_bin ? That’s it).
\nTake a look at the documentation :<\/p>\n
For binary strings (BINARY, VARBINARY, BLOB), comparisons use the numeric values of the bytes in the operands; this means that for alphabetic characters, comparisons will be case sensitive.<\/p><\/blockquote>\n
http:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/case-sensitivity.html<\/a><\/p>\n
So that’s why the\u00a0query did not return what was expected .. Change the collation to utf8 DEFAULT (or utf8_general_ci) :<\/p>\n
ALTER TABLE `service` CHANGE `description` `description` VARCHAR(255) CHARSET utf8 COLLATE utf8_general_ci NULL;<\/pre>\n
And now it works.<\/p>\n","protected":false},"excerpt":{"rendered":"
Today at work I helped an intern with an interesting problem I would like to share. he was doing this kind of query on a MySQL server : SELECT description FROM service WHERE description LIKE ‘%cloud%’; It returned these lines : cloud customer 1 cloud customer 2 but does not return these two lines he\u00a0was … Continuer la lecture de MySQL SELECT query with LIKE case sensitive ?<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,6],"tags":[36],"class_list":["post-151","post","type-post","status-publish","format-standard","hentry","category-informatique","category-php-sql","tag-mysql"],"yoast_head":"\nMySQL SELECT query with LIKE case sensitive ? - My thoughts<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.olivierdoucet.info\/blog\/2014\/11\/13\/mysql-select-query-case-sensitive\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"MySQL SELECT query with LIKE case sensitive ? 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