Oracle

Recently participated in a number of interviews, summed up the competition in the Oracle development post most frequently asked what questions:1, delete and truncate difference? 1) Truncate is a DDL statement. Delete is a DML statement;2) Truncate

Recently participated in several interviews. Summarize the most frequently asked questions about the competition for Oracle development positions:1, delete and truncate difference? 1) Truncate is a DDL statement, and delete is a DML statement;2)

1, under normal circumstances, we are not access to Ojdbc.jar, need to establish a local warehouse.2, first find your own Oracle Ojdbc.jar put it into the C:\Users\Administrator directory, and then execute the following codeMVN

Write a simple query statement1. Display all the information of the Department tableSelect * FROM Dept;2. Show department number, department nameSelectdeptno,dname from Dept;3. Displays the connection for the following fields and strings: Employee

1. View the log file location.[email protected]>select inst_id,name,value from V$diag_info;inst_id NAME VALUE---------- -------------------- --------------------------------------------------1 Diag Enabled TRUE1 ADR base/u01/app/oracle1 ADR Home/u01/

Advantages of using Views:1. Simplify data manipulation: Views Simplify how users work with data.2. Focus on specific data: unnecessary data or sensitive data can not be present in the view.3. The view provides a simple and effective security

1, look for redundant records in the table, duplicate records are based on a single field (ID) to determineSELECT * FROM table where Id in (select ID from table group Byid have count (Id) > 1)2, delete redundant records in the table, duplicate

--Add, modify, and delete constraints--1. Add Constraint ALTER TABLE tableAdd[constraint constraint]Constraint_type (column1[, Column2,...])[constraint_parameters];Alter TableBooks Modify Title not NULL;--add a non-null constraint--2. Modifying

Rollup Function Application Scenario:　　The main use in the grouping, each group to the total value (that is, subtotal), and finally all values (minus subtotals) sum (is total)Of course, the same effect can be achieved with union. Identify the groups

In the Oracle database environment of their own virtual machine, when tossing and making experiments, do not know what special changes, operations caused from the Sql*plus to start the database instance, reported the following error:Then use startup

--Create the user create user XX identified by "", default tablespace USERS temporary tablespace TEMP profile default Password expire;--grant/revoke role privileges Grant connect to Xx;grant Ctxapp to Xx;grant dba to Xx;grant exp_full_database to xx;

Installing Oracle-database-server-12cr2-preinstallwget http://public-yum.oracle.com/public-yum-ol7.repo-o/etc/yum.repos.d/ Public-yum-ol7.repowget http://public-yum.oracle.com/rpm-gpg-key-oracle-ol7-o/etc/ Pki/rpm-gpg/rpm-gpg-key-oracleYum Clean

The new feature after oracle11g makes it possible to omit empty tables when allocating table spaces by default, to reduce the resource usage of tablespaces, so that empty tables are ignored when exporting user data using the EXP export of Oracle,

When debugging code encountered such a problem, the program run to the SQL statement to throw invalid character exception, then I had to copy the SQL statement, in Oracle to execute, but there is nothing wrong, this can be difficult for me, so I can

Open instance, database to Nomount state:Startup Nomount;Parameter fileMemory, ProcessSpecifying control filesThe database opens to the Mount State:Alter Datatbase Mount;Control filesWhat data files are included, what log filesBackup-related

Oracle Flashback is a fast and easy database recovery technology, it does not use backup files, through the flashback log can restore the database to a state of the past, when the user logic error (delete table data, table, table space, etc.) need

The amount of space (table capacity) of statistical tables/* Generally, the table occupies three parts: Table data, table index, table blob field data */--1 Statistics the space occupied by a single table with (BLOB field)SELECT table_name, SUM

How does Oracle work? Select ID , name from the T order by ID; –sql parsing (see if the syntax is incorrect, if there are no errors, parse the semantics, execute permissions on this statement)– Execution Plan (howORACLE accesses data

return in conditional processing methodpublic static string InsertParameters (ref list orclparameters, int[] lsids, String uniqueparname ){String Strparametros = String. Empty;for (int i = 0; I {Strparametros + = i = = 0? ":" + uniqueparname + I: ",:

Management SectionIf database force logging is not enabled, the repository/*+ append */operation, nologging operation, will report the bad block;Suggested table space Force logging or database force logging;Test:Select Force_logging, tablespace_name