PL SQL 多表关联更新

UPDATE TABLE1 T1   SET T1.USERTIME =       (SELECT T2.USERTIME FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID) WHERE EXISTS (SELECT 1 FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID);--更新多个字段：UPDATE TABLE1 T1   SET A.USERTIME    =       (SELECT T2.USERTIME FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID),       T1.PROCESSFLAG =       (SELECT T2.PROCESSFLAG FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID) WHERE EXISTS (SELECT 1 FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID);--多表关系更新：UPDATE TABLE1 T1   SET T1.USERTIME   =       (SELECT T2.USERTIME FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID),       T1.PROCESSFLAG =       (SELECT T3.PROCESSFLAG FROM TABLE3 T3 WHERE T3.MSGID = T1.MSGID) WHERE EXISTS (SELECT 1 FROM TABLE2 T2 WHERE T2.MSGID_DB = T1.MSGID)   AND EXISTS (SELECT 1 FROM TABLE3 T3 WHERE T3.MSGID = T1.MSGID);