Get MySQL Cookbook now with the O’Reilly learning platform. Unavailable, in which case you can use only ALTER TABLE. Wish to convert the column so that it is not case sensitive, you canĪLTER TABLE news MODIFY article TEXT NOT NULL ĪLTER TABLE news CHANGE article article TEXT NOT NULL Suppose you have a table in which you store news articles:īLOB, which is a case-sensitive type. Type that is not suitable for the kind of comparisons for which you If you find that you’ve declared a column using a Need not take lettercase into account during the comparison. Slightly faster than non-case-sensitive comparisons, because MySQL In general, case-sensitive comparisons involving binary strings are You can still use the BINARY keyword beforeĬomparisons to produce a case sensitive operation.Ĭase Sensitivity and String Comparison Speed Numbers, you cannot declare them case sensitive in the tableĭefinition by adding the BINARY keyword. Furthermore, because they are stored internally as Literal strings or string expressions, or CHAR,Ĭase sensitive. Literal string or string expression, or a CHAR BINARY, VARCHAR BINARY, or BLOB column.Ĭomparisons are not case sensitive if they involve only non-binary In summary, comparisons are case sensitive if they involve a binary For example, the result returned by thisĬONCAT( ) expression is binary because its secondĬONCAT('This is a ',BINARY 'binary',' string')Ĭase sensitive by default, but may be declared asĬase sensitive. IfīINARY is not present, the following rules apply.Ī string expression is binary if any of its constituent strings isīinary, otherwise not. To avoid surprises in string comparisons, know the general rules thatĭetermine whether or not a string is binary:Īny literal string, string expression, or string column can be madeīinary by preceding it with the BINARY keyword. Operator, which returns zero and nonzero for inequality and equality. Return values from STRCMP( ) indicate equality and ![]() | STRCMP(BINARY 'Abc','abc') | STRCMP(BINARY 'abc','Abc') |īy the way, take special note of the fact that zero and nonzero Mysql> SELECT STRCMP(BINARY 'Abc','abc'), STRCMP(BINARY 'abc','Abc') To preserve the pre-4.0.1 behavior, make one of the arguments a However, as of MySQL 4.0.1, STRCMP( ) is not case To make a string comparison not case sensitive that normally wouldīe, convert both strings to the same lettercase using UPPER( ) or LOWER( ): | name | name = BINARY 'lead' | BINARY name = 'LEAD' |īINARY is available as a cast operator as of MySQL Mysql> SELECT name, name = BINARY 'lead', BINARY name = 'LEAD' FROM metal Is, the comparison will be case sensitive: Matter which of the strings you make binary. To make a string comparison case sensitive that normally would notīe, cast (convert) one of the strings to binary form by using the ![]() To control case sensitivity in stringĬomparisons, use the following techniques: String comparisons are case sensitive only if at least one of the String ordering is done by default without regard for lettercase, so Uppercase letters, so the results in the second comparison column of You know that lowercase letters have higher ASCII codes than If you’re familiar with the ASCII collating order, Mysql> SELECT name, name < 'lead', name < 'LEAD' FROM metal The lack of case sensitivity also applies to relative ordering String comparisons in MySQL are not case sensitive by default: mysql> SELECT name, name = 'lead', name = 'LEAD' FROM metal Recipe 4.11 covers case sensitivity in pattern-matching Section describes how to do that for ordinary comparisons. But sometimes you need to make sure a string operation isĬase sensitive that would not otherwise be, or vice versa. The examples in previous sections were performed without regard to
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