Программа базы данных C++ SQL

Вы можете получить достаточно диагностических данных из SQL, чтобы вы могли изолировать и решить проблему.

Вы можете получить дескриптор оператора, чтобы сообщить вам, что с ним пошло не так, вызвав, когда SQLExecDirect возвращает что-то, отличное от SQL_SUCCESS или SQL_SUCCESS_WITH_INFO.

SQLGetDiagRec( SQL_HANDLE_STMT, StatementHandle, req, state, &error, (SQLCHAR*) buffer, (SQLINTEGER) MAX_CHAR, (SQLSMALLINT*) &output_length );

Вам, конечно, придется выделить переменные, которые вы видите здесь ... Я предлагаю вам поместить строку выброса после вызова SQLGetDiagRec и назначить ей точку останова. Когда он там сломается, вы можете посмотреть на значение state: оно будет соответствовать разделу «Диагностика» здесь: http://msdn.microsoft.com/en-us/library/ms713611(VS.85).aspx

Хорошо, вот код теперь работает ...

using namespace std;    // to save us having to type std::

const int MAX_CHAR = 1024;

int main ( )
{
     SQLSMALLINT     RecNumber;
     SQLCHAR *       SQLState;
     SQLINTEGER *    NativeErrorPtr;
     SQLCHAR *       MessageText;
     SQLSMALLINT     BufferLength;
     SQLSMALLINT *   TextLengthPtr;

    SQLCHAR   SQLStmt[MAX_CHAR];
    char      strSQL[MAX_CHAR];
    char      chrTemp;

    SQLVARCHAR rtnFirstName[50];
    SQLVARCHAR rtnLastName[50];
    SQLVARCHAR rtnAddress[30];
    SQLVARCHAR rtnCity[30];
    SQLVARCHAR rtnState[3];
    SQLDOUBLE  rtnSalary;
    SQLVARCHAR rtnGender[2];
    SQLINTEGER rtnAge;

    // Get a handle to the database

    SQLHENV EnvironmentHandle;
    RETCODE retcode = SQLAllocHandle( SQL_HANDLE_ENV, SQL_NULL_HANDLE, &EnvironmentHandle );

    // Set the SQL environment flags

    retcode = SQLSetEnvAttr( EnvironmentHandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, SQL_IS_INTEGER );

    // create handle to the SQL database

    SQLHDBC ConnHandle;
    retcode = SQLAllocHandle( SQL_HANDLE_DBC, EnvironmentHandle, &ConnHandle );

    // Open the database using a System DSN

    retcode = SQLDriverConnect(ConnHandle, 
        NULL, 
        (SQLCHAR*)"DSN=PRG411;UID=myUser;PWD=myPass;", 
        SQL_NTS,
        NULL, 
        SQL_NTS, 
        NULL, 
        SQL_DRIVER_NOPROMPT);
    if (!retcode) 
    {
        cout << "SQLConnect() Failed";
    }
    else
    {
        // create a SQL Statement variable

        SQLHSTMT StatementHandle;
        retcode = SQLAllocHandle(SQL_HANDLE_STMT, ConnHandle, &StatementHandle);

        // Part 1: Create the Employee table (Database)

        do
        {
            cout << "Create the new table? ";
            cin >> chrTemp;
        } while (cin.fail());

        if (chrTemp == 'y' || chrTemp == 'Y')
        {
            strcpy((char *) SQLStmt, "CREATE TABLE [dbo].[Employee]([pkEmployeeID] [int] IDENTITY(1,1) NOT NULL,[FirstName] [varchar](50) NOT NULL,[LastName] [varchar](50) NOT NULL,[Address] [varchar](30) NOT NULL,[City] [varchar](30) NOT NULL,[State] [varchar](3) NOT NULL, [Salary] [decimal] NOT NULL,[Gender] [varchar](1) NOT NULL,  [Age] [int] NOT NULL, CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED ([pkEmployeeID] ASC)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]) ON [PRIMARY]");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);
        }

        // Part 2: Hardcode records into the table

        do
        {
            cout << "Add records to the table? ";
            cin >> chrTemp;
        } while (cin.fail());

        if (chrTemp == 'y' || chrTemp == 'Y')
        {
            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Mike','Slentz','123 Torrey Dr.','North Clairmont','CA', 48000.00 ,'M',34)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Sue','Vander Hayden','46 East West St.','San Diego','CA', 36000.00 ,'F',28)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Sharon','Stonewall','756 West Olive Garden Way','Plymouth','MA', 56000.00 ,'F',58)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('James','Bartholemew','777 Praying Way','Falls Church','VA', 51000.00 ,'M',45)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Joe','Smith','111 North 43rd Ave','Peoria','AZ', 44000.00 ,'M', 40)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Michael','Smith','20344 North Swan Park','Phoenix','AZ', 24000.00 ,'M', 40)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Jennifer','Jones','123 West North Ave','Flagstaff','AZ', 40000.00 ,'F', 40)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Cora','York','33rd Park Way Drive','Mayville','MI', 30000.00 ,'F', 61)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

            strcpy((char *) SQLStmt, "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Tom','Jefferson','234 Friendship Way','Battle Creek','MI', 41000.00 ,'M', 31)");
            retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);
        }

        // Part 3 & 4: Searchs based on criteria

        do
        {
            cout << "1. Display all records in the database" << endl;
            cout << "2. Display all records with age 40 or over" << endl;
            cout << "3. Display all records with salary K or over" << endl;
            cout << "4. Exit" << endl << endl;

            do
            {
                cout << "Please enter a selection: ";
                cin >> chrTemp;
            } while (cin.fail());

            if (chrTemp == '1')
            {
                strcpy((char *) SQLStmt, "SELECT [FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age] FROM EMPLOYEE");
            }
            else if (chrTemp == '2')
            {
                strcpy((char *) SQLStmt, "SELECT [FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age] FROM EMPLOYEE WHERE [AGE] >= 40");
            }
            else if (chrTemp == '3')
            {
                strcpy((char *) SQLStmt, "SELECT [FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age] FROM EMPLOYEE WHERE [Salary] >= 30000");
            }

            if (chrTemp == '1'  || chrTemp == '2' || chrTemp == '3')
            {
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                //SQLGetDiagRec(SQL_HANDLE_STMT, StatementHandle, RecNumber, SQLState, NativeErrorPtr, (SQLCHAR*) MessageText, (SQLINTEGER) BufferLength, (SQLSMALLINT*) &TextLengthPtr);

                SQLBindCol(StatementHandle, 1, SQL_C_CHAR, &rtnFirstName, sizeof(rtnFirstName), NULL );
                SQLBindCol(StatementHandle, 2, SQL_C_CHAR, &rtnLastName, sizeof(rtnLastName), NULL );
                SQLBindCol(StatementHandle, 3, SQL_C_CHAR, &rtnAddress, sizeof(rtnAddress), NULL );
                SQLBindCol(StatementHandle, 4, SQL_C_CHAR, &rtnCity, sizeof(rtnCity), NULL );
                SQLBindCol(StatementHandle, 5, SQL_C_CHAR, &rtnState, sizeof(rtnState), NULL );
                SQLBindCol(StatementHandle, 6, SQL_C_DOUBLE, &rtnSalary, sizeof(rtnSalary), NULL );
                SQLBindCol(StatementHandle, 7, SQL_C_CHAR, &rtnGender, sizeof(rtnGender), NULL );
                SQLBindCol(StatementHandle, 8, SQL_C_LONG, &rtnAge, sizeof(rtnAge), NULL );

                for(;;) 
                {
                    retcode = SQLFetch(StatementHandle);
                    if (retcode == SQL_NO_DATA_FOUND) break;

                    cout << rtnFirstName << " " << rtnLastName << " " << rtnAddress << " " << rtnCity << " " << rtnState << " " << rtnSalary << " " << rtnGender << " " << rtnAge << endl;
                }

                SQLFreeStmt(StatementHandle, SQL_CLOSE);

            }
        } while (chrTemp != '4');

        SQLFreeStmt(StatementHandle, SQL_CLOSE );
        SQLFreeHandle(SQL_HANDLE_STMT, StatementHandle);

        SQLDisconnect(ConnHandle);

        SQLFreeHandle(SQL_HANDLE_DBC, ConnHandle);
        SQLFreeHandle(SQL_HANDLE_ENV, EnvironmentHandle);

        printf( "Done.\n" );
    }

    return 0;
}

Вы сказали, что получаете ошибки с:

строка sqlString = "Выберите * от клиентов, где Customers.Employee = '" + id + "'";

Это должно быть очевидно, извините, лол. Идентификатор, конечно же, целое число. Но когда вы оцениваете строку, она выглядит так:

string sqlString = "Выберите * от клиентов, у которых Customers.Employee = '100'";

Обратите внимание, что не так? Вы заключите его в одинарные кавычки. Таким образом, независимо от того, какой тип данных вы используете, одинарные кавычки заставляют SQL рассматривать его как строку. Так что просто вытащите их вот так:

строка sqlString = "Выберите * От клиентов, где Customers.Employee =" + id + ""; . . . . . . . Или же, строка sqlString = "Выберите * От клиентов, где Customers.Employee =" + id;

У меня такой вопрос ... Можете ли вы объяснить, как работает циклический просмотр записей в C++? Например, пользователь вводит имя пользователя в strUName, и вы хотите увидеть, находится ли это имя пользователя в таблице базы данных Users. SQL достаточно прост (выберите * из списка пользователей, где [UName] = '"+ strUName +"'; Но как на самом деле выполнить его на C++ и выяснить это?

Я вижу SQLStmt, я вижу, что он выполняется с использованием Direct. Затем я вижу некоторый мусор SQLBindCol, а затем бесконечный цикл до тех пор, пока не произойдет остановка. Но я не совсем понимаю, что происходит (для меня это легко для любого другого языка, но я новичок в C++.

Вот исправленный код.

    #include <iostream>
    #include <cstdio>
    #include <string>

    #include <windows.h>
    #include <sql.h>
    #include <sqlext.h>
    #include <sqltypes.h> 

    using namespace std;    // to save us having to type std::

    const int MAX_CHAR = 1024;

    int main()
    {
        SQLSMALLINT     RecNumber;
        SQLCHAR *       SQLState;
        SQLINTEGER *    NativeErrorPtr;
        SQLCHAR *       MessageText;
        SQLSMALLINT     BufferLength;
        SQLSMALLINT *   TextLengthPtr;

        SQLCHAR   SQLStmt[MAX_CHAR];
        char      strSQL[MAX_CHAR];
        char      chrTemp;

        SQLVARCHAR rtnFirstName[50];
        SQLVARCHAR rtnLastName[50];
        SQLVARCHAR rtnAddress[30];
        SQLVARCHAR rtnCity[30];
        SQLVARCHAR rtnState[3];
        SQLDOUBLE  rtnSalary;
        SQLVARCHAR rtnGender[2];
        SQLINTEGER rtnAge;

        // Get a handle to the database

        SQLHENV EnvironmentHandle;
        RETCODE retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &EnvironmentHandle);

        // Set the SQL environment flags
        HWND desktopHandle = GetDesktopWindow();
        retcode = SQLSetEnvAttr(EnvironmentHandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, SQL_IS_INTEGER);

        // create handle to the SQL database

        SQLHDBC ConnHandle;
        retcode = SQLAllocHandle(SQL_HANDLE_DBC, EnvironmentHandle, &ConnHandle);
        SQLSetConnectAttr(ConnHandle, SQL_LOGIN_TIMEOUT, (SQLPOINTER)5, 0);
        // Open the database using a System DSN

        retcode = SQLDriverConnect(ConnHandle,
            desktopHandle,
            (SQLCHAR*)"DSN=PRG411;UID=myUser;PWD=myPass;",
            SQL_NTS,
            NULL,
            SQL_NTS,
            NULL,
            SQL_DRIVER_NOPROMPT);
        if (retcode != SQL_SUCCESS || retcode != SQL_SUCCESS_WITH_INFO)
        {
            cout << "SQLConnect() Failed";
        }   
        else
        {
            // create a SQL Statement variable

            SQLHSTMT StatementHandle;
            retcode = SQLAllocHandle(SQL_HANDLE_STMT, ConnHandle, &StatementHandle);

            // Part 1: Create the Employee table (Database)

            do
            {
                cout << "Create the new table? ";
                cin >> chrTemp;
            } while (cin.fail());

            if (chrTemp == 'y' || chrTemp == 'Y')
            {
                strcpy_s((char *)SQLStmt,1024,  "CREATE TABLE [dbo].[Employee]([pkEmployeeID] [int] IDENTITY(1,1) NOT NULL,[FirstName] [varchar](50) NOT NULL,[LastName] [varchar](50) NOT NULL,[Address] [varchar](30) NOT NULL,[City] [varchar](30) NOT NULL,[State] [varchar](3) NOT NULL, [Salary] [decimal] NOT NULL,[Gender] [varchar](1) NOT NULL,  [Age] [int] NOT NULL, CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED ([pkEmployeeID] ASC)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]) ON [PRIMARY]");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);
            }

            // Part 2: Hardcode records into the table

            do
            {
                cout << "Add records to the table? ";
                cin >> chrTemp;
            } while (cin.fail());

            if (chrTemp == 'y' || chrTemp == 'Y')
            {
                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Mike','Slentz','123 Torrey Dr.','North Clairmont','CA', 48000.00 ,'M',34)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Sue','Vander Hayden','46 East West St.','San Diego','CA', 36000.00 ,'F',28)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Sharon','Stonewall','756 West Olive Garden Way','Plymouth','MA', 56000.00 ,'F',58)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('James','Bartholemew','777 Praying Way','Falls Church','VA', 51000.00 ,'M',45)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Joe','Smith','111 North 43rd Ave','Peoria','AZ', 44000.00 ,'M', 40)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Michael','Smith','20344 North Swan Park','Phoenix','AZ', 24000.00 ,'M', 40)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Jennifer','Jones','123 West North Ave','Flagstaff','AZ', 40000.00 ,'F', 40)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Cora','York','33rd Park Way Drive','Mayville','MI', 30000.00 ,'F', 61)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                strcpy_s((char *)SQLStmt,1024,  "INSERT INTO employee([FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age]) VALUES ('Tom','Jefferson','234 Friendship Way','Battle Creek','MI', 41000.00 ,'M', 31)");
                retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);
            }

            // Part 3 & 4: Searchs based on criteria

            do
            {
                cout << "1. Display all records in the database" << endl;
                cout << "2. Display all records with age 40 or over" << endl;
                cout << "3. Display all records with salary K or over" << endl;
                cout << "4. Exit" << endl << endl;

                do
                {
                    cout << "Please enter a selection: ";
                    cin >> chrTemp;
                } while (cin.fail());

                if (chrTemp == '1')
                {
                    strcpy_s((char *)SQLStmt,1024,  "SELECT [FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age] FROM EMPLOYEE");
                }
                else if (chrTemp == '2')
                {
                    strcpy_s((char *)SQLStmt,1024,  "SELECT [FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age] FROM EMPLOYEE WHERE [AGE] >= 40");
                }
                else if (chrTemp == '3')
                {
                    strcpy_s((char *)SQLStmt,1024,  "SELECT [FirstName], [LastName], [Address], [City], [State], [Salary], [Gender],[Age] FROM EMPLOYEE WHERE [Salary] >= 30000");
                }

                if (chrTemp == '1' || chrTemp == '2' || chrTemp == '3')
                {
                    retcode = SQLExecDirect(StatementHandle, SQLStmt, SQL_NTS);

                    //SQLGetDiagRec(SQL_HANDLE_STMT, StatementHandle, RecNumber, SQLState, NativeErrorPtr, (SQLCHAR*) MessageText, (SQLINTEGER) BufferLength, (SQLSMALLINT*) &TextLengthPtr);

                    SQLBindCol(StatementHandle, 1, SQL_C_CHAR, &rtnFirstName, sizeof(rtnFirstName), NULL);
                    SQLBindCol(StatementHandle, 2, SQL_C_CHAR, &rtnLastName, sizeof(rtnLastName), NULL);
                    SQLBindCol(StatementHandle, 3, SQL_C_CHAR, &rtnAddress, sizeof(rtnAddress), NULL);
                    SQLBindCol(StatementHandle, 4, SQL_C_CHAR, &rtnCity, sizeof(rtnCity), NULL);
                    SQLBindCol(StatementHandle, 5, SQL_C_CHAR, &rtnState, sizeof(rtnState), NULL);
                    SQLBindCol(StatementHandle, 6, SQL_C_DOUBLE, &rtnSalary, sizeof(rtnSalary), NULL);
                    SQLBindCol(StatementHandle, 7, SQL_C_CHAR, &rtnGender, sizeof(rtnGender), NULL);
                    SQLBindCol(StatementHandle, 8, SQL_C_LONG, &rtnAge, sizeof(rtnAge), NULL);

                    for (;;)
                    {
                        retcode = SQLFetch(StatementHandle);
                        if (retcode == SQL_NO_DATA_FOUND) break;

                        cout << rtnFirstName << " " << rtnLastName << " " << rtnAddress << " " << rtnCity << " " << rtnState << " " << rtnSalary << " " << rtnGender << " " << rtnAge << endl;
                    }

                    SQLFreeStmt(StatementHandle, SQL_CLOSE);

                }
            } while (chrTemp != '4');

            SQLFreeStmt(StatementHandle, SQL_CLOSE);
            SQLFreeHandle(SQL_HANDLE_STMT, StatementHandle);

            SQLDisconnect(ConnHandle);

            SQLFreeHandle(SQL_HANDLE_DBC, ConnHandle);
            SQLFreeHandle(SQL_HANDLE_ENV, EnvironmentHandle);

            printf("Done.\n");
        }

        return 0;
    }