问用于替换保持大小写不变的文本的MySQL函数

EN

DELIMITER $$
DROP FUNCTION IF EXISTS `replace_ci`$$
CREATE FUNCTION `replace_ci` (str TEXT, needle CHAR(255), str_rep CHAR(255))
    RETURNS TEXT
    DETERMINISTIC
    BEGIN
        DECLARE return_str TEXT DEFAULT '';
        DECLARE lower_str TEXT;
        DECLARE lower_needle TEXT;
        DECLARE pos INT DEFAULT 1;
        DECLARE old_pos INT DEFAULT 1;
        SELECT lower(str) INTO lower_str;
        SELECT lower(needle) INTO lower_needle;
        SELECT locate(lower_needle, lower_str, pos) INTO pos;
        WHILE pos > 0 DO
            SELECT concat(return_str, substr(str, old_pos, pos-old_pos), str_rep) INTO return_str;
            SELECT pos + char_length(needle) INTO pos;
            SELECT pos INTO old_pos;
            SELECT locate(lower_needle, lower_str, pos) INTO pos;
        END WHILE;
        SELECT concat(return_str, substr(str, old_pos, char_length(str))) INTO return_str;

        /** mirror the case **/
        IF (BINARY LEFT(str,1) = LOWER(LEFT(str,1))) THEN
            SET return_str = LOWER(return_str);
        ELSE
            IF (BINARY LEFT(str,2) = UPPER(LEFT(str,2))) THEN
                SET return_str = UPPER(return_str);
            ELSE          
                SET return_str = CONCAT( UPPER(LEFT(return_str,1)), LOWER(RIGHT(return_str, LENGTH(return_str) - 1)) );
            END IF;
        END IF;

        RETURN return_str;
END$$
DELIMITER ;