fastdb 内存数据库使用实例

Posted 2021-05-16 zsl6658

      最近一个月忙死了,没有时间发表文章.先是出差一个月,做一个电话自动应答系统.忙的焦头烂额.一个月只休息了三天.现在还晕呢.这两天终于完事了,又让我研究fastdb的使用.今天就来灌个fastdb的例子.

     首先下载fastdb的源代码,make源代码里边的makefile.windows运行makefile.mvc.编译生成fastdb.lib.如果是BCB 把所有的源代码,所有的*.cpp包含到一个library工程,然后build.就会生成一个fastdb.lib.这一块差点把我给唬了.我用BCB,先make makefile.mvc生成fastdb.lib,然后编写一个自己的测试.结果链接报错,说我的lib是coff格式,而需要omf格式,网上一查,有人说BCB中就没有办法使用coff格式的lib.我晕!最后同学提醒,直接把所有的cpp包含到一个lib工程,然后build,生成的lib可以使用了.呵呵!别的不说了.下面把例子的源代码贴出来,有兴趣的自己看吧,这几天太累了,不想写,想休息.休息去了!88!有点长,复制的时候才看出来了!等那天休息好了,解释一下里边的东西!

#include <stdio.h>
#include "fastdb.h"

USE_FASTDB_NAMESPACE

class Contract;

class Detail {
  public:
    char const* name;
    char const* material;
    char const* color;
    real4       weight;

    dbArray< dbReference<Contract> > contracts;

    TYPE_DESCRIPTOR((KEY(name, INDEXED|HASHED),
                     KEY(material, HASHED),
                     KEY(color, HASHED),
                     KEY(weight, INDEXED),
                     RELATION(contracts, detail)));
};

class Supplier {
  public:
    char const* company;
    char const* location;
    bool        foreign;

    dbArray< dbReference<Contract> > contracts;

    TYPE_DESCRIPTOR((KEY(company, INDEXED|HASHED),
                     KEY(location, HASHED),
                     FIELD(foreign),
                     RELATION(contracts, supplier)));
};

class Contract {
  public:
    dbDateTime            delivery;
    int4                  quantity;
    db_int8                  price;
    dbReference<Detail>   detail;
    dbReference<Supplier> supplier;

    TYPE_DESCRIPTOR((KEY(delivery, HASHED|INDEXED),
                     KEY(quantity, INDEXED),
                     KEY(price, INDEXED),
                     RELATION(detail, contracts),
                     RELATION(supplier, contracts)));
};

REGISTER(Detail);
REGISTER(Supplier);
REGISTER(Contract);

void input(char const* prompt, char* buf, size_t buf_size)
{
    char* p;
    do {
        printf(prompt);
        *buf = '/0';
        fgets(buf, buf_size, stdin);
        p = buf + strlen(buf);
    } while (p <= buf+1);
   
    if (*(p-1) == '/n') {
        *--p = '/0';
    }
}

int main()
{
    const int maxStrLen = 256;

    dbDatabase db;

    char buf[maxStrLen];
    char name[maxStrLen];
    char company[maxStrLen];
    char material[maxStrLen];
    char address[maxStrLen];

    int d, m, y;
    int i, n;
    int choice;
    int quantity;
    db_int8 price;

    dbDateTime from, till;

    Contract contract;
    Supplier supplier;
    Detail detail;

    dbQuery q1, q2, q3, q4, q6, q9, q10;
    q1 = "exists i:(contracts[i].supplier.company=",company,")";
    q2 = "name like",name;
    q3 = "supplier.location =",address;
    q4 = between("delivery", from, till),"and price >",price,
        "order by",dbDateTime::ascent("delivery");
    q6 = "price >=",price,"or quantity >=",quantity;
    q9 = "company =",company;
    q10 = "supplier.company =",company,"and detail.name like",name;

    dbCursor<Detail>   details;
    dbCursor<Contract> contracts;
    dbCursor<Supplier> suppliers;
    dbCursor<Contract> updateContracts(dbCursorForUpdate);
       
    if (db.open("testdb")) {
        while (true) {
            printf(
"/n/n    MENU:/n/
1.  Details shipped by supplier/n/
2.  Suppliers of the detail/n/
3.  Contracts from specified city/n/
4.  Expensive details to be delivered in specified period/n/
5.  Foreign suppliers/n/
6.  Important contracts/n/
7.  New supplier/n/
8.  New detail/n/
9.  New contract/n/
10. Cancel contract/n/
11. Update contract/n/
12. Exit/n/n");
            input(">> ", buf, sizeof buf);
            if (sscanf(buf, "%d", &choice) != 1) {
                continue;
            }
            switch (choice) {
              case 1:
                printf("Details shipped by supplier/n");
                input("Supplier company: ", company, sizeof company);
                if (details.select(q1) > 0) {
                    printf("Detail/tMaterial/tColor/tWeight/n");
                    do {
                        printf("%s/t%s/t%s/t%f/n",
                               details->name, details->material,
                               details->color, details->weight);
                    } while (details.next());
                } else {
                    printf("No details shipped by this supplier/n");
                }
                break;
              case 2:
                printf("Suppliers of the detail/n");
                input("Regular expression for detail name: ",name,sizeof name);
                if (details.select(q2) > 0) {
                    printf("Detail/tCompany/tLocation/tPrice/n");
                    do {
                        n = details->contracts.length();
                        for (i = 0; i < n; i++) {
                            contracts.at(details->contracts[i]);
                            suppliers.at(contracts->supplier);
                            printf("%s/t%s/t%s/t" INT8_FORMAT "/n",
                                   details->name,
                                   suppliers->company, suppliers->location,
                                   contracts->price);
                        }
                    } while (details.next());
                } else {
                    printf("No such details/n");
                }
                break;
              case 3:
                printf("Contracts from specified city/n");
                input("City: ", address, sizeof address);
                if (contracts.select(q3) > 0) {
                    printf("Detail/tCompany/tQuantity/n");
                    do {
                        printf("%s/t%s/t%d/n",
                               details.at(contracts->detail)->name,
                               suppliers.at(contracts->supplier)->company,
                               contracts->quantity);
                    } while (contracts.next());
                } else {
                    printf("No contracts with companies in this city");
                }
                break;
              case 4:
                printf("Expensive details to be delivered in specified period/n");
                input("Delivered after (DD-MM-YYYY): ", buf, sizeof buf);
                if (sscanf(buf, "%d-%d-%d/n", &d, &m, &y) != 3) {
                    printf("Wrong date/n");
                    continue;
                }
                from = dbDateTime(y, m, d);
                input("Delivered before (DD-MM-YYYY): ", buf, sizeof buf);
                if (sscanf(buf, "%d-%d-%d/n", &d, &m, &y) != 3) {
                    printf("Wrong date/n");
                    continue;
                }
                till = dbDateTime(y, m, d);
                input("Minimal contract price: ", buf, sizeof buf);
                if (sscanf(buf, INT8_FORMAT, &price) != 1) {
                    printf("Bad value/n");
                    continue;
                }
                if (contracts.select(q4) > 0) {
                    printf("Detail/tDate/tPrice/n");
                    do {
                        printf("%s/t%s/t" INT8_FORMAT "/n",
                               details.at(contracts->detail)->name,
                               contracts->delivery.asString(buf, sizeof buf),
                               contracts->price);
                    } while (contracts.next());
                } else {
                    printf("No such contracts/n");
                }
                break;
              case 5:
                printf("Foreign suppliers/n");
                if (suppliers.select("foreign and length(contracts) > 0") > 0){
                    printf("Company/tLocation/n");
                    do {
                        printf("%s/t%s/n", suppliers->company,
                               suppliers->location);
                    } while (suppliers.next());
                } else {
                    printf("No such suppliers/n");
                }
                break;
              case 6:
                printf("Important contracts/n");
                input("Minimal contract price: ", buf, sizeof buf);
                if (sscanf(buf, INT8_FORMAT, &price) != 1) {
                    printf("Bad value/n");
                    continue;
                }
                input("Minimal contract quantity: ", buf, sizeof buf);
                if (sscanf(buf, "%d", &quantity) != 1) {
                    printf("Bad value/n");
                    continue;
                }
                if (contracts.select(q6) > 0) {
                    printf("Company/tPrice/tQuantity/tDelivery/n");
                    do {
                        printf("%s/t" INT8_FORMAT "/t%d/t%s/n",
                               suppliers.at(contracts->supplier)->company,
                               contracts->price, contracts->quantity,
                               contracts->delivery.asString(buf, sizeof buf,
                                                            "%A %x"));
                    } while (contracts.next());
                } else {
                    printf("No such contracts/n");
                }
                break;
              case 7:
                printf("New supplier/n");
                input("Company name: ", company, sizeof company);
                input("Company location: ", address, sizeof address);
                input("Foreign company (y/n): ", buf, sizeof buf);
                supplier.company = company;
                supplier.location = address;
                supplier.foreign = (*buf == 'y');
                insert(supplier);
                break;
              case 8:
                printf("New detail/n");
                input("Detail name: ", name, sizeof name);
                input("Detail material: ", material, sizeof material);
                input("Detail weight: ", buf, sizeof buf);
                sscanf(buf, "%f", &detail.weight);
                input("Detail color: ", buf, sizeof buf);
                detail.name = name;
                detail.material = material;
                detail.color = buf;
                insert(detail);
                break;
              case 9:
                printf("New contract/n");
                db.lock(); // prevent deadlock
                input("Supplier company: ", company, sizeof company);
                if (suppliers.select(q9) == 0) {
                    printf("No such supplier/n");
                    continue;
                }
                input("Detail name: ", name, sizeof name);
                if (details.select(q2) == 0) {
                    printf("No such detail/n");
                    continue;
                } else if (details.getNumberOfRecords() != 1) {
                    printf("More than one record match this pattern");
                    continue;
                }
                input("Contract price: ", buf, sizeof buf);
                sscanf(buf, INT8_FORMAT, &contract.price);
                input("Contract quantity: ", buf, sizeof buf);
                sscanf(buf, "%d", &contract.quantity);
                input("Delivered after (days): ", buf, sizeof buf);
                sscanf(buf, "%d", &d);
                contract.delivery =
                    dbDateTime::currentDate() + dbDateTime(24*d,0);
                contract.supplier = suppliers.currentId();
                contract.detail = details.currentId();
                insert(contract);
                break;
              case 10:
                printf("Cancel contract/n");
                input("Supplier company: ", company, sizeof company);
                input("Detail name pattern: ", name, sizeof name);
                if (updateContracts.select(q10) == 0) {
                    printf("No such contracts/n");
                } else {
                    updateContracts.removeAllSelected();
                    // Just test rollback
                    input("Really cancel contract (y/n) ? ", buf, sizeof buf);
                    if (*buf != 'y') {
                        printf("Not confirmed/n");
                        db.rollback();
                        continue;
                    }
                }
                break;
              case 11:
                printf("Update contract/n");
                input("Supplier company: ", company, sizeof company);
                input("Detail name pattern: ", name, sizeof name);
                if (updateContracts.select(q10) == 0) {
                    printf("No such contracts/n");
                    break;
                }              
                do {
                    printf("Contract with company %s for shipping %d details "
                           "%s for $" INT8_FORMAT " at %s/n",
                           suppliers.at(updateContracts->supplier)->company,
                           updateContracts->quantity,
                           details.at(updateContracts->detail)->name,
                           updateContracts->price,
                           updateContracts->delivery.asString(buf,sizeof buf));
                    input("Change this contract (y/n) ? ", buf, sizeof buf);
                    if (*buf == 'y') {
                        input("New contract price: ", buf, sizeof buf);
                        sscanf(buf, INT8_FORMAT, &updateContracts->price);
                        input("New number of details: ", buf, sizeof buf);
                        sscanf(buf, "%d", &updateContracts->quantity);
                        updateContracts.update();
                    }
                } while (updateContracts.next());
                break;
              case 12:
                input("Do you really want to exit (y/n) ? ", buf, sizeof buf);
                if (*buf == 'y') {
                    printf("Close database session/n");
                    db.close();
                    return EXIT_SUCCESS;
                }
                break;
              default:
                printf("Please choose menu items 1..12/n");
                continue;
            }
            printf("Press any key to continue.../n");
            getchar();
            db.commit();
        }
    } else {
        printf("failed to open database/n");
        return EXIT_FAILURE;
    }
}