无法使用 QT 在 sqlite 中存储二进制数据 [英] Not able to store binary data in sqlite using QT

问题描述

无法使用 QT 将所有二进制数据值存储到 sqlite3 表中.

为此，我创建了一个 BLOB 数据列来存储名为 logTable 的二进制数据表.我正在尝试将二进制数据插入 binary_data[] 缓冲区，其值为 0x1 到 0xFF 和 0x00 到 0xFF 等等，直到 1024 字节.但是当我执行查询来存储数据时，该表只显示 0x1 到 0xFF，但没有存储剩余的字符(因为下一个立即数是 0x00).我想存储所有的二进制数据值?

For this I have created a BLOB data column to store binary data table named as logTable. I am trying to insert binary data to binary_data[] buffer, with values as 0x1 to 0xFF and 0x00 to 0xFF and so on till 1024 bytes. But when I execute the query to store the data, the table shows only 0x1 to 0xFF, but remaining character are not getting stored (since next immediate value is 0x00). I want to store all the binary data values?

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    conect_to_log_db("./log.db");

    unsigned char binary_data[1024];

    for(unsigned int i = 0, value = 1; i < 1024; i++, value++)
    {
        binary_data[i] = value;
    }
    store_to_log_db("01/02/2012,13:03:58", binary_data, 1024);
    ......
}


bool store_to_log_db(QString dateTime, unsigned char *data, unsigned int dataLength)
{
    QSqlQuery objQuery(objLogsDB);

    QString query = "CREATE TABLE IF NOT EXISTS logTable(logDateTime VARCHAR(19), packet BLOB, direction INTEGER)";
    objQuery.exec(query);

    QByteArray dataArr;
    dataArr.resize(dataLength);
    for(unsigned int i = 0; i < dataLength; i++)
    {
        dataArr[i] = data[i];
    }

    QVariant blobData = dataArr.data();

    objQuery.prepare("INSERT INTO logTable VALUES(:logDateTime,:packet,:direction)");
    objQuery.bindValue(":logDateTime",dateTime);
    objQuery.bindValue(":packet",blobData,QSql::In | QSql::Binary);
    objQuery.bindValue(":direction",1);

    qDebug() << objQuery.exec();

    return true;
}

执行这段代码后，当我使用sqlite输出时，表的结果是254个字符

after executing this code, the result of the table is till 254 characters when I output from sqlite using

$sqlite3 日志.db

$sqlite3 log.db

sqlite>.output try.txt

sqlite>.output try.txt

sqlite>select * from logTable;

sqlite>select * from logTable;

$ls -l try.txt

$ls -l try.txt

大小为 406 字节

推荐答案

您必须使用 .dump.sqlite3 交互式客户端不输出 BLOB 列.

You must use .dump. The sqlite3 interactive client doesn't output BLOB columns.

$sqlite3 log.db
sqlite> .output try.txt
sqlite> .dump
sqlite> .quit

下面的代码是创建一个简单的包含 blob 的数据库的自包含示例.

The code below is a self contained example of creating a simple blob-containing database.

// https://github.com/KubaO/stackoverflown/tree/master/questions/sqlite-blob-11062145
#include <QtSql>

int main()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("./log.db");

    if (!db.open()) { qDebug() << "can't open the database"; return 1; }

    QSqlQuery query{db};

    query.exec("DROP TABLE log");

    if (!query.exec("CREATE TABLE log(packet BLOB)"))
        qDebug() << "create table failed";

    QVariant data[2] = {QByteArray{1024, 1}, QByteArray{2048, 2}};

    query.prepare("INSERT INTO log VALUES(:packet)");

    query.bindValue(":packet", data[0], QSql::In | QSql::Binary);
    if (!query.exec()) qDebug() << "insert failed";

    query.bindValue(":packet", data[1], QSql::In | QSql::Binary);
    if (!query.exec()) qDebug() << "insert failed";

    db.close();

    if (!db.open()) { qDebug() << "can't reopen the database"; return 2; }

    query.prepare("SELECT (packet) FROM log");
    if (!query.exec()) qDebug() << "select failed";

    for (auto const & d : data) if (query.next()) {
        qDebug() << query.value(0).toByteArray().size() << d.toByteArray().size();
        if (d != query.value(0)) qDebug() << "mismatched readback value";
    }

    db.close();
}

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