linux下c语言通过Freetds读取mssql中数据的代码并且保证无中文乱码

要在Linux下使用C语言通过FreeTDS读取MSSQL中的数据，需要使用FreeTDS库，并且在连接数据库时设置字符集为UTF-8。以下是一个示例代码，可以读取MSSQL数据库中的数据，并保证无中文乱码。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sybfront.h>
#include <sybdb.h>

#define SQL_RESULT_LEN 1024

int main() {
    LOGINREC *login;
    DBPROCESS *dbproc;
    DBBOOL success;
    RETCODE retcode;

    char *server = "your_server_name";
    char *user = "your_username";
    char *pass = "your_password";
    char *database = "your_database_name";

    char sql[SQL_RESULT_LEN];
    char name[SQL_RESULT_LEN];
    char age[SQL_RESULT_LEN];
    char address[SQL_RESULT_LEN];
    char phone[SQL_RESULT_LEN];

    if (dbinit() == FAIL) {
        printf("Error initializing FreeTDS.\n");
        return 1;
    }

    login = dblogin();
    DBSETLUSER(login, user);
    DBSETLPWD(login, pass);
    DBSETLAPP(login, "myapp");
    DBSETLVERSION(login, "70");
    DBSETLCHARSET(login, "UTF-8");

    dbproc = dbopen(login, server);
    if (dbproc == NULL) {
        printf("Error connecting to the database.\n");
        return 1;
    }

    success = dbuse(dbproc, database);
    if (success == FAIL) {
        printf("Error selecting database.\n");
        return 1;
    }

    // 注意：这里的 SQL 语句需要根据实际情况进行修改
    sprintf(sql, "SELECT name, age, address, phone FROM your_table_name");
    retcode = dbcmd(dbproc, sql);

    if (retcode != SUCCEED) {
        printf("Error executing SQL statement.\n");
        return 1;
    }

    retcode = dbsqlexec(dbproc);
    if (retcode != SUCCEED) {
        printf("Error executing SQL statement.\n");
        return 1;
    }

    while (dbresults(dbproc) != NO_MORE_RESULTS) {
        while (dbnextrow(dbproc) != NO_MORE_ROWS) {
            dbbind(dbproc, 1, NTBSTRINGBIND, 0, name);
            dbbind(dbproc, 2, NTBSTRINGBIND, 0, age);
            dbbind(dbproc, 3, NTBSTRINGBIND, 0, address);
            dbbind(dbproc, 4, NTBSTRINGBIND, 0, phone);

            dbnullbind(dbproc, 1, &name[0]);
            dbnullbind(dbproc, 2, &age[0]);
            dbnullbind(dbproc, 3, &address[0]);
            dbnullbind(dbproc, 4, &phone[0]);

            dbdata(dbproc, 1, (BYTE *)name, strlen(name));
            dbdata(dbproc, 2, (BYTE *)age, strlen(age));
            dbdata(dbproc, 3, (BYTE *)address, strlen(address));
            dbdata(dbproc, 4, (BYTE *)phone, strlen(phone));

            printf("%s\t%s\t%s\t%s\n", name, age, address, phone);
        }
    }

    dbexit();
    return 0;
}

需要注意的是，在连接数据库时需要设置字符集为UTF-8，具体方法是使用`DBSETLCHARSET`函数，例如：

DBSETLCHARSET(login, "UTF-8");