Are UNIQUE indices case sensitive in MySQL?

问题

Are indices (indexes) defined as UNIQUE case sensitive in MySQL?

回答1:

It depends on the collation of the field - if it's ci (case insensitive) or cs (case sensitive). The unique index would apply accordingly.

回答2:

You can make a column case-sensitive by using this syntaxis. the unique index also will be case-sensitive.

ALTER TABLE tbl_name MODIFY
col_name column_definition
[CHARACTER SET charset_name]
[COLLATE collation_name]

Example:

ALTER TABLE `tablename` MODIFY
`column` VARCHAR(100) 
CHARACTER SET utf8
COLLATE utf8_bin;

Note: utf8_bin compares strings by the binary value of each character in the string.

Tested on Msql 5.5.X

回答3:

There's nothing special about UNIQUE indexes - they follow the same case options as other indexes.

来源：https://stackoverflow.com/questions/463764/are-unique-indices-case-sensitive-in-mysql