Video: Kev siv ResultSetMetaData hauv Java yog dab tsi?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
ResultSetMetaData yog ib qho interface hauv java. sql ua pob ntawm JDBC API uas yog siv kom tau txais cov metadata txog cov khoom ResultSet. Thaum twg koj nug cov ntaub ntawv siv SELECT nqe lus, qhov tshwm sim yuav muab khaws cia rau hauv cov khoom ResultSet. Txhua ResultSet object yog txuam nrog ib yam khoom ResultSetMetaData.
Hais txog qhov no, dab tsi yog getMetaData hauv Java?
Cov getMetaData () txoj kev ntawm ResultSet interface retrieves ResultSetMetaData kwv ntawm qhov ResultSet tam sim no. Txoj kev no xa rov qab rau ResultSetMetaData cov khoom uas tuav cov lus piav qhia ntawm Cov Khoom Siv ResultSet kab.
Kuj Paub, qhov txawv ntawm ResultSet thiab ResultSetMetaData yog dab tsi? ResultSetMetaData yog ib chav kawm uas siv los nrhiav cov ntaub ntawv hais txog cov ResultSet rov qab los ntawm executeQuery hu. Nws muaj cov ntaub ntawv hais txog tus naj npawb ntawm kab, hom ntaub ntawv uas lawv muaj, cov npe ntawm kab, thiab lwm yam.
Kuj Paub, dab tsi yog metadata hauv Java nrog piv txwv?
Muab qhov ntawd metadata yog cov txheej txheem piav qhia, qauv thiab kev tswj hwm cov ntaub ntawv hais txog ib pawg ntawm cov ntaub ntawv hauv computer (rau piv txwv xws li database schema), Java Metadata Interface (los yog JMI) yog lub platform-nruab nrab specification uas txhais cov creation, cia, nkag mus, nrhiav thiab pauv ntawm metadata hauv Java programming
Yuav ua li cas rov qab ResultSetMetaData kwv piav txog ResultSet?
Feem ntau siv txoj kev ntawm ResultSetMetaData interface. nws rov qab los tag nrho cov naj npawb ntawm kab hauv lub ResultSet khoom . nws rov qab los lub npe kem ntawm cov kab ke teev index. nws rov qab los kab ntawv hom npe rau qhov ntsuas qhov ntsuas.
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