MySQL 4.0 to 4.1
  • MySQL interprets length specifications in character column definitions in characters. (Earlier versions interpret them in bytes.) For example, CHAR(N) means N characters, not N bytes.
  • In MySQL 4.1, string comparison works according to the SQL standard: Instead of stripping end spaces before comparison, the shorter string is extended using spaces. This means that 'a' > 'a\t', which it was not previously. If you have any tables containing an indexed CHAR, VARCHAR or TEXT column in which the last character in the index may be less than ASCII(32), you should use REPAIR TABLE or mysqlcheck to ensure that the table is correct.
  • TIMESTAMP is returned in MySQL 4.1 as a string in 'YYYY-MM-DD HH:MM:SS' format. (See Section 11.3.1.2, “TIMESTAMP Properties as of MySQL 4.1”.) Display widths for TIMESTAMP columns are no longer supported in MySQL 4.1. For example, if you declare a column as TIMESTAMP(10), the (10) is ignored.
  • Binary values such as 0xFFDF are assumed to be strings instead of numbers. This fixes some problems with character sets where it is convenient to input a string as a binary value.
  • Before MySQL 4.1.1, the statement parser was less strict and its string-to-date conversion would ignore everything up to the first digit. As a result, invalid statements such as the following were accepted: "INSERT INTO t (datetime_col) VALUES ('stuff 2005-02-11 10:17:01')" As of MySQL 4.1.1, the parser is stricter and treats the string as an invalid date, so the preceding statement results in a warning.