MariaDB/MySQL UDF to capitalize the first letter of each word in a space separated string. Tested on MariaDB 5.5.33a on Ubuntu 12.10.

word_uc.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "mysql.h"

// sudo gcc -Wall -std=c11 -I/usr/include/mysql -shared word_uc.c -o /usr/lib/mysql/plugin/word_uc.so -fPIC

my_bool word_uc_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
{
    if (args->arg_count != 1) {
            memcpy(message, "Missing message argument.", 26);
            return 1;
    }
    if (args->arg_type[0] != STRING_RESULT) {
            args->arg_type = STRING_RESULT;
    }
    return 0;
}


// -------------------------------

char *word_uc(
    UDF_INIT *initid,
    UDF_ARGS *args,
    char *result,
    unsigned long *length,
    char *is_null,
    char *error
)
{
    *length = strlen(args->args[0]);
    if (*length > 255) {
        *is_null = 1;
        return NULL;
    }

    size_t space_flag = 0;
    size_t str_len = strlen(args->args[0]);

	char* temp = (char*)malloc(sizeof args->args[0]);

    for (size_t i = 0; i < str_len; ++i) {

        if (i == 0 || (islower(args->args[0][i]) && space_flag)) {
            temp[i] = toupper(args->args[0][i]);
            space_flag = 0;
        } else {
            if (isspace(args->args[0][i])) {
                space_flag = 1;
            }
            temp[i] = args->args[0][i];
        }

    }

    sprintf(result, "%s", temp);

    /* Free it up!!! */
    free(temp);

    return result;
}