Student's Problem

#include <stdio.h>
#include <string.h>
struct database {
    char bookname[50];
    int studentid;
    char studentname[50];
    char takendate[50];
    char returndate[50];
    char deptname[50];
};
int INDEX = 0;
struct database LB[200];

void insert() {
    printf("Enter the name of book:\n");
    fflush(stdin);
    scanf("%s", LB[INDEX].bookname);
    fflush(stdout);

    printf("Enter student id no:\n");
    scanf("%d", &LB[INDEX].studentid);
    /*

    printf("Enter the name of student:\n");
    fflush(stdin);
    scanf("%s", LB[INDEX].studentname);
    fflush(stdout);

    printf("Enter the date when taken:\n");
    fflush(stdin);
    scanf("%s", LB[INDEX].takendate);
    fflush(stdout);

    printf("Enter the return date:\n");
    fflush(stdin);
    scanf("%s", LB[INDEX].returndate);
    fflush(stdout);

    printf("Enter the name of department:\n");
    fflush(stdin);
    scanf("%s", LB[INDEX].deptname);
    fflush(stdout);
    */

    printf("All information has been inserted!\n\n");
    INDEX++;
}

void show() {
    int i;
    if (INDEX == 0) {
        printf("List is empty\n\n");
    } else {
        for (i = 0; i < INDEX; i++) {
            printf("The name of Book: %s\n", LB[i].bookname);
            printf("Student id no: %d\n", LB[i].studentid);
            printf("Name of the student: %s\n", LB[i].studentname);
            printf("Taken date: %s\n", LB[i].takendate);
            printf("Return date: %s\n", LB[i].returndate);
            printf("Department of the student: %s\n", LB[i].deptname);

            printf("\n");
        }
    }
}
void query() {
    char desirebookname[50];
    printf("Enter the name of book which need to find:\n");
    scanf("%s", desirebookname);

    int i;

    if (INDEX == 0) {
        printf("List is empty\n\n");
        return;
    }
    int dsr = 0;
    for (i = 0; i < INDEX; i++) {
        char check[200];
        strcpy(LB[i].studentname, check);

        if (strcmp(check, desirebookname) == 0) {
            dsr = i;
            printf("Student id no: %d\n", LB[dsr].studentid);
            printf("Name of the student: %s\n", LB[dsr].studentname);
            printf("Taken date: %s\n", LB[dsr].takendate);
            printf("Return date: %s\n", LB[dsr].returndate);
            printf("Department of the student: %s\n", LB[dsr].deptname);
        }
    }
}

int main() {
    int choice;

    while (1) {
        printf("Menu\n");
        printf("1. Insert data\n");
        printf("2. Show database\n");
        printf("3. query\n");
        printf("Enter your choice:\n");
        scanf("%d", &choice);

        if (choice == 1) {
            insert();
        } else if (choice == 2) {
            show();
        } else if (choice == 3) {
            query();
        } else if (choice == 4) {
            break;
        } else {
            printf("Error!\n\n");
        }
    }
}