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CppSQLite - C++ Wrapper for SQLite

2020-12-06 23:24:55 havealex

CodeProject There is a story about Windows Under the system SQLite Of C++ Wrapper class , The specific address is :CppSQLite - C++ Wrapper for SQLite, As shown in the figure below : CppSqlite CppSqlite Is based on sqlite C Of language base C++ Simple encapsulation .

As mentioned in the introduction : This article describes CppSQLite, a very thin C++ wrapper around the public domain SQLite database library.

A description of how to link applications with SQLite is provided, then an example program using CppSQLite is presented, and finally the CppSQLite classes are documented.

To set the scene, here is a quote from the SQLite author...

SQLite is a C library that implements an embeddable SQL database engine. Programs that link with the SQLite library can have SQL database access without running a separate RDBMS process. The distribution comes with a standalone command-line access program (SQLite) that can be used to administer a SQLite database and which serves as an example of how to use the SQLite library.

SQLite is not a client library used to connect to a big database server. SQLite is the server. The SQLite library reads and writes directly to and from the database files on disk. This library is in Windows Next Visual Studio It works better in the environment , It's from 2011 I haven't updated it for a long time .

CppSQLite Class

#include "CppSQLite.h"
#include <ctime>
#include <iostream>

using namespace std;

const char* gszFile = "C:\\test.db";

int main(int argc, char** argv)
{
    try
    {
        int i, fld;
        time_t tmStart, tmEnd;
        CppSQLiteDB db;

        cout << "SQLite Version: " << db.SQLiteVersion() << endl;

        remove(gszFile);
        db.open(gszFile);

        cout << endl << "Creating emp table" << endl;
        db.execDML("create table emp(empno int, empname char(20));");
        ///////////////////////////////////////////////////////////////
        // Execute some DML, and print number of rows affected by each one
        ///////////////////////////////////////////////////////////////
        cout << endl << "DML tests" << endl;
        int nRows = db.execDML("insert into emp values (7, 'David Beckham');");
        cout << nRows << " rows inserted" << endl;

        nRows = db.execDML(
         "update emp set empname = 'Christiano Ronaldo' where empno = 7;");
        cout << nRows << " rows updated" << endl;

        nRows = db.execDML("delete from emp where empno = 7;");
        cout << nRows << " rows deleted" << endl;

        /////////////////////////////////////////////////////////////////
        // Transaction Demo
        // The transaction could just as easily have been rolled back
        /////////////////////////////////////////////////////////////////
        int nRowsToCreate(50000);
        cout << endl << "Transaction test, creating " << nRowsToCreate;
        cout << " rows please wait..." << endl;
        tmStart = time(0);
        db.execDML("begin transaction;");

        for (i = 0; i < nRowsToCreate; i++)
        {
            char buf[128];
            sprintf(buf, "insert into emp values (%d, 'Empname%06d');", i, i);
            db.execDML(buf);
        }

        db.execDML("commit transaction;");
        tmEnd = time(0);

        ////////////////////////////////////////////////////////////////
        // Demonstrate CppSQLiteDB::execScalar()
        ////////////////////////////////////////////////////////////////
        cout << db.execScalar("select count(*) from emp;") 
               << " rows in emp table in ";
        cout << tmEnd-tmStart << " seconds (that was fast!)" << endl;

        ////////////////////////////////////////////////////////////////
        // Re-create emp table with auto-increment field
        ////////////////////////////////////////////////////////////////
        cout << endl << "Auto increment test" << endl;
        db.execDML("drop table emp;");
        db.execDML(
         "create table emp(empno integer primary key, empname char(20));");
        cout << nRows << " rows deleted" << endl;

        for (i = 0; i < 5; i++)
        {
            char buf[128];
            sprintf(buf, 
       "insert into emp (empname) values ('Empname%06d');", i+1);
            db.execDML(buf);
            cout << " primary key: " << db.lastRowId() << endl;
        }

     ///////////////////////////////////////////////////////////////////
     // Query data and also show results of inserts into auto-increment field
     //////////////////////////////////////////////////////////////////
        cout << endl << "Select statement test" << endl;
        CppSQLiteQuery q = db.execQuery("select * from emp order by 1;");

        for (fld = 0; fld < q.numFields(); fld++)
        {
            cout << q.fieldName(fld) << "(" << q.fieldType(fld) << ")|";
        }
        cout << endl;

        while (!q.eof())
        {
            cout << q.fieldValue(0) << "|";
            cout << q.fieldValue(1) << "|" << endl;
            q.nextRow();
        }

        ///////////////////////////////////////////////////////////////
        // SQLite's printf() functionality. Handles embedded quotes and NULLs
        ////////////////////////////////////////////////////////////////
        cout << endl << "SQLite sprintf test" << endl;
        CppSQLiteBuffer bufSQL;
        bufSQL.format("insert into emp (empname) values (%Q);", "He's bad");
        cout << (const char*)bufSQL << endl;
        db.execDML(bufSQL);

        bufSQL.format("insert into emp (empname) values (%Q);", NULL);
        cout << (const char*)bufSQL << endl;
        db.execDML(bufSQL);

        ////////////////////////////////////////////////////////////////////
        // Fetch table at once, and also show how to 
        // use CppSQLiteTable::setRow() method
        //////////////////////////////////////////////////////////////////
        cout << endl << "getTable() test" << endl;
        CppSQLiteTable t = db.getTable("select * from emp order by 1;");

        for (fld = 0; fld < t.numFields(); fld++)
        {
            cout << t.fieldName(fld) << "|";
        }
        cout << endl;
        for (int row = 0; row < t.numRows(); row++)
        {
            t.setRow(row);
            for (int fld = 0; fld < t.numFields(); fld++)
            {
                if (!t.fieldIsNull(fld))
                    cout << t.fieldValue(fld) << "|";
                else
                    cout << "NULL" << "|";
            }
            cout << endl;
        }

        ////////////////////////////////////////////////////////////////////
        // Test CppSQLiteBinary by storing/retrieving some binary data, checking
        // it afterwards to make sure it is the same
        //////////////////////////////////////////////////////////////////
        cout << endl << "Binary data test" << endl;
        db.execDML("create table bindata(desc char(10), data blob);");
        
        unsigned char bin[256];
        CppSQLiteBinary blob;

        for (i = 0; i < sizeof bin; i++)
        {
            bin[i] = i;
        }

        blob.setBinary(bin, sizeof bin);

        bufSQL.format("insert into bindata values ('testing', %Q);", 
                      blob.getEncoded());
        db.execDML(bufSQL);
        cout << "Stored binary Length: " << sizeof bin << endl;

        q = db.execQuery("select data from bindata where desc = 'testing';");

        if (!q.eof())
        {
            blob.setEncoded((unsigned char*)q.fieldValue("data"));
            cout << "Retrieved binary Length: " 
       << blob.getBinaryLength() << endl;
        }

        const unsigned char* pbin = blob.getBinary();
        for (i = 0; i < sizeof bin; i++)
        {
            if (pbin[i] != i)
            {
                cout << "Problem: i: ," << i << " bin[i]: " 
             << pbin[i] << endl;
            }
        }

        /////////////////////////////////////////////////////////
        // Pre-compiled Statements Demo
        /////////////////////////////////////////////////////////////
        cout << endl << "Transaction test, creating " << nRowsToCreate;
        cout << " rows please wait..." << endl;
        db.execDML("drop table emp;");
        db.execDML("create table emp(empno int, empname char(20));");
        tmStart = time(0);
        db.execDML("begin transaction;");

        CppSQLiteStatement stmt = db.compileStatement(
            "insert into emp values (?, ?);");
        for (i = 0; i < nRowsToCreate; i++)
        {
            char buf[16];
            sprintf(buf, "EmpName%06d", i);
            stmt.bind(1, i);
            stmt.bind(2, buf);
            stmt.execDML();
            stmt.reset();
        }

        db.execDML("commit transaction;");
        tmEnd = time(0);

        cout << db.execScalar("select count(*) from emp;") 
           << " rows in emp table in ";
        cout << tmEnd-tmStart << " seconds (that was even faster!)" << endl;
        cout << endl << "End of tests" << endl;
    }
    catch (CppSQLiteException& e)
    {
        cerr << e.errorCode() << ":" << e.errorMessage() << endl;
    }

    ////////////////////////////////////////////////////////////////
    // Loop until user enters q or Q
    ///////////////////////////////////////////////////////////
    char c(' ');

    while (c != 'q' && c != 'Q')
    {
        cout << "Press q then enter to quit: ";
        cin >> c;
    }
    return 0;
}

Some classes

CppSQLite.h and CppSQLite.cpp The document includes CppSQLiteException、CppSQLiteDB、CppSQLiteQuery、CppSQLiteTable、CppSQLiteBuffer、CppSQLiteStatement These classes , It can be used for one's own with only a few changes C++ In the project .

Reference material

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