SESSION 1：SQL> select * from v$mystat where rownum<2; SID STATISTIC# VALUE---------- ---------- ---------- 1 0 0SQL> select * from a1; ID FLAG1 FLAG2---------- ---------- ---------- 1 a a1 1 b b1SQL> update a1 set id=2 where flag1='a';1 row updated.SESSION 2：SQL> update a1 set id=2 where flag1='a';SQL> select * from v$lock;ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------35000FE8 35001014 12 XR 4 0 1 0 208 03500105C 35001088 12 RD 1 0 1 0 208 0350010D0 350010FC 12 CF 0 0 2 0 208 0350011B8 350011E4 12 RS 25 1 2 0 204 03500122C 35001258 1 AE 100 0 4 0 123 0350012A0 350012CC 11 RT 1 0 6 0 204 035001314 35001340 10 PW 1 0 3 0 200 035001388 350013B4 13 TS 3 1 3 0 201 0350013FC 35001428 15 AE 100 0 4 0 195 035001470 3500149C 10 MR 1 0 4 0 202 0350014E4 35001510 10 MR 2 0 4 0 202 0ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------35001558 35001584 10 MR 3 0 4 0 202 0350015CC 350015F8 10 MR 4 0 4 0 202 035001640 3500166C 10 MR 5 0 4 0 202 0350016B4 350016E0 10 MR 201 0 4 0 202 035001728 35001754 25 AE 100 0 4 0 180 03500179C 350017C8 26 AE 100 0 4 0 94 035001810 3500183C 17 AE 100 0 4 0 177 035001884 350018B0 26 TX 393229 9322 0 6 92 0350018F8 35001924 31 AE 100 0 4 0 9 000FF8BF4 00FF8C24 26 TM 75517 0 3 0 92 000FF8BF4 00FF8C24 1 TM 75517 0 3 0 103 0ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------33140924 33140964 1 TX 393229 9322 6 0 103 123 rows selected.SQL> select * from v$lock where sid in (1,26);ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------3500122C 35001258 1 AE 100 0 4 0 332 03500179C 350017C8 26 AE 100 0 4 0 303 035001884 350018B0 26 TX 393229 9322 0 6 301 001015210 01015240 26 TM 75517 0 3 0 301 001015210 01015240 1 TM 75517 0 3 0 312 033140924 33140964 1 TX 393229 9322 6 0 312 16 rows selected.SQL> create table a as select * from v$lock where sid in (1,26);Table created.SQL> create table b as select * from v$lock where sid in (1,26);Table created.SQL> select hold.sid, block.sid from a hold ,b blockwhere hold.id1=block.id1and block.request<>0and hold.sid<>block.sid 2 3 4 5 ; SID SID---------- ---------- 1 26