达梦数据库存二进制大文件

达梦数据库存储文件的2种方式：

1.通过存储过程在数据库中存储二进制大文件：

//使用BFILE、BLOB类型，通过存储过程在数据库中存储二进制大对象
create directory LOGDIR as '/home';

CREATE TABLE FILE_LOB
(
T_ID INT NOT NULL,
T_FILE BLOB NOT NULL,
PRIMARY KEY(T_ID)
);

CREATE OR REPLACE PROCEDURE FILE_INSERT
(
TID INT,
FILENAME VARCHAR(200)
)
AS
F_LOB BFILE;
B_LOB BLOB;
BEGIN
	INSERT INTO FILE_LOB (T_ID,T_FILE) VALUES (TID,EMPTY_BLOB())
	RETURN T_FILE INTO B_LOB;
	F_LOB := BFILENAME('LOGDIR',FILENAME);
	DBMS_LOB.FILEOPEN(F_LOB,DBMS_LOB.FILE_READONLY);
	DBMS_LOB.LOADFROMFILE(B_LOB,F_LOB,
	DBMS_LOB.GETLENGTH(F_LOB));
	DBMS_LOB.FILECLOSE(F_LOB);
	COMMIT;
END;

2. 直接在程序中将文件内容转为二进制，并插入表中的BLOB字段：

#include <QCoreApplication>
#include <QtSql>
#include <QDebug>
#include <QTextCodec>

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

    QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
    db.setHostName("192.168.104.21");
    db.setPort(51236);
    db.setDatabaseName("DM8");
    db.setUserName("SYSDBA");
    db.setPassword("SYSDBA");
    if (db.open())
        qDebug() << "connect ok!";
    else
    {
        qDebug() << "connect fail! " << db.lastError().text().toLatin1();
    }

    QSqlQuery query;

    //清理测试环境
    QString strsql = "drop table if exists qt_demo";
    query.exec(strsql);
    strsql = "create table qt_demo(c1 int, c2 blob)";
    query.exec(strsql);

    // 读取文件数据，写入 lob 列
    //选择要写入的文件
    QString f = "../qt_lob/file/DM8_SQL.pdf";

    //转换为字节数组
    QByteArray mapData;
    QFile file(f);
    file.open(QIODevice::ReadOnly);
    mapData = file.readAll();
    file.close();

    //插入数据
    query.prepare("INSERT INTO qt_demo values(?, ?)");
    query.bindValue(0, 1);
    query.bindValue(1, mapData);
    if (!query.exec()) {
        qDebug() << query.lastError();
    } else {
        qDebug() << "insert OK!";
    }

    //读取 lob 列数据，写入到文件中
    QSqlQuery readquery;

    QByteArray databa;
    if (readquery.exec("select c2 from provider_demo")) {
        QSqlRecord myrecord = readquery.record();

        if (readquery.next()) {
            databa = readquery.value(myrecord.indexOf("C2")).toByteArray();
        }
    }

    QFile mybfile("../qt_lob/file/DM81_SQL.pdf");
    mybfile.open(QIODevice::WriteOnly);
    mybfile.write(databa);
    mybfile.close();
    qDebug() << "select OK!";


    return a.exec();
}