c++ - 检索 Oracle OCCI 结果集中列的数据类型信息

Question

通过 OCCI 发送一个简单的查询后(例如:select * from ALL_USERS)我需要知道该列的数据类型，目前我一直在使用 ResultSet::getColumnListMetaData( ) 方法没有成功。
问题:
1.如何使用上述方法和MetaData类获取数据类型？
2. 有没有比 oracle 已经提供的文档更好的文档？

Answer 1

我手边有这段旧代码，我猜它完全符合您的要求。它使用 OCI，而不是 OCCI，但也许有帮助。

/* Get the number of columns in the query */
ub4 colCount = 0;
oraCheckErr( m_err, OCIAttrGet((dvoid *)_stmt, OCI_HTYPE_STMT, (dvoid *)&colCount,
                    0, OCI_ATTR_PARAM_COUNT, m_err));

ub2 oraType = 0;
OCIParam *col = 0;

ub4 nameLen, colWidth, charSemantics;
text *name;

for (ub4 i = 1; i <= colCount; i++)
{
    /* get parameter for column i */
    oraCheckErr( m_err, OCIParamGet((dvoid *)_stmt, OCI_HTYPE_STMT, m_err, (dvoid**)&col, i));

    /* get data-type of column i */
    oraType = 0;
    oraCheckErr( m_err, OCIAttrGet((dvoid *)col, OCI_DTYPE_PARAM,
            (dvoid *)&oraType, 0, OCI_ATTR_DATA_TYPE,  m_err));

    /* Retrieve the column name attribute */
    nameLen = 0;
    oraCheckErr( m_err, OCIAttrGet((dvoid*)col, OCI_DTYPE_PARAM,
            (dvoid**) &name, &nameLen, OCI_ATTR_NAME, m_err ));

    /* Retrieve the length semantics for the column */
    charSemantics = 0;
    oraCheckErr( m_err, OCIAttrGet((dvoid*)col, OCI_DTYPE_PARAM,
            (dvoid*) &charSemantics,0, OCI_ATTR_CHAR_USED, m_err ));

    colWidth = 0;
    if (charSemantics)
        /* Retrieve the column width in characters */
        oraCheckErr( m_err, OCIAttrGet((dvoid*)col, OCI_DTYPE_PARAM,
                (dvoid*) &colWidth, 0, OCI_ATTR_CHAR_SIZE, m_err ));
    else
        /* Retrieve the column width in bytes */
        oraCheckErr( m_err, OCIAttrGet((dvoid*)col, OCI_DTYPE_PARAM,
                (dvoid*) &colWidth,0, OCI_ATTR_DATA_SIZE, m_err ));

    _elements.output.push_back( SQLElement( String(reinterpret_cast<char*>(name), nameLen), getSQLTypes( oraType ), i, colWidth ));
}

OCIHandleFree ( (dvoid*) _stmt, OCI_HTYPE_STMT );

编辑:根据您的要求:

SQLTypes getSQLTypes(ub2 _oracleType)
{
switch( _oracleType )
{
    case SQLT_INT:
        return stInt;
    case SQLT_FLT:
    case SQLT_BDOUBLE:
        return stDouble;
    case SQLT_BFLOAT:
        return stFloat;
    case SQLT_ODT:
        return stDate;

    case SQLT_DATE:
    case SQLT_TIMESTAMP:
    case SQLT_TIMESTAMP_TZ:
    case SQLT_TIMESTAMP_LTZ:
        return stTimeStamp;

    case SQLT_CHR:
    case SQLT_NUM:
    case SQLT_STR:
    case SQLT_VCS:
    default:
        return stText;
}
}