SQL

How to Resolve ORA-01861: literal does not match format string

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ORA-01861 ORA-01861 means that different format between two operands can not be compared. In this post, you will see some error patterns and their respective solutions. The following statement looks like no problem. SQL> conn hr/hr Connected. SQL> set heading off; SQL> select count(*) || ‘ Persons’ from employees where hire_date > ‘2008-03-01’; select count(*) […]
Data Guard

Connect-Time Failover to Standby Database

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We’re going to introduce 3 ways that can failover to a standby database at connect-time in this post. Using a Persistent Service Name Using a Dynamic Service Name Using a SRVCTL Configured Service Using a Persistent Service Name Connect-Time Failover is a feature of local naming method, and can be easily set up by adding […]
Index

How to Resolve ORA-08102: index key not found

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ORA-08102 Found some ORA-08102 errors during executions of SQL statements like this: ERROR at line 1: ORA-08102: index key not found, obj# 98830, file 69, block 120164 (2) ERROR at line 1: ORA-08102: index key not found, obj# 98832, file 69, block 120172 (2) ERROR at line 1: ORA-08102: index key not found, obj# 98831, […]
SQL

How to Revert INSERT INTO by DELETE FROM Statements

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Revert INSERT INTO Suppose that you have created two rows by INSERT INTO statements like this: SQL> INSERT INTO HR.EMPLOYEES (EMPLOYEE_ID, LAST_NAME, EMAIL, HIRE_DATE, JOB_ID) VALUES (207, ‘Chen’, ‘chen@example.com’, ’25-APR-19′, ‘SA_REP’); 1 row created. SQL> INSERT INTO HR.EMPLOYEES (EMPLOYEE_ID, LAST_NAME, EMAIL, HIRE_DATE, JOB_ID) VALUES (208, ‘Smit’, ‘smit@example.com’, ’25-APR-19′, ‘FI_MGR’); 1 row created. If you are […]
Alert Log File

Where is Oracle Alert Log Location

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The Default Location of Oracle Alert Log The location of Oracle alert log may not be easily found, but it’s usually at 3 possible locations: For 11g and Above $ORACLE_BASE/diag/rdbms/<dbname_in_lower_case>/$ORACLE_SID/trace/ As we can notice, Oracle software divides alert logs to their own dedicated directories according to their database names, which is based on directory structure […]
Listener Log

Where is Oracle Listener Log Location

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The Default Location of Oracle Listener Log If you have read Where to Find Oracle Alert Log Location, you may have some clues to find the right listener.log. But there’re some differences between them. For 11g and above The default location of listener log for 11g or above can be found at: [oracle@ora11g ~]$ ll […]
RMAN

How to Resolve ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode

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Found ORA-19602 When I tried to backup a NOARCHIVELOG database in MOUNT state, I got ORA-19602 like the following case: RMAN> startup mount; … RMAN> backup database tag ‘20190416-before-yearly-import’; Starting backup at 16-APR-19 using target database control file instead of recovery catalog allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=393 device type=DISK channel ORA_DISK_1: starting full datafile […]
Database Link

What DB Link Can and Cannot Do

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Can and Cannot For better understanding the features of a database link which may play an important role in data migration, we should study what a database link can and cannot do in a distributed database system in order to develop our data migration strategy. Generally speaking, you can perform Data Query Language (DQL) and […]
SQL

How to Resolve ORA-00903: invalid table name

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In this post, I will introduce 3 main error patterns about ORA-00903, they are: Violating Naming Rules Missing Quotes Incorrect Syntax ORA-00903 due to Violating Naming Rules Without complying with database object naming rules, we can’t create a table with unusual strings in normal way. Let’s see some cases that throw ORA-00903. First of all, […]