How to find the Oracle SID?

Run SELECT*FROMv$version; you can obtain the complete version information of the Oracle database, including the database, PL/SQL, core library, etc. version details, which is the most commonly used reliable method for DBA; 2. Use SELECTbannerFROMv$versionWHEREbannerLIKE'Oracle%'; you can only display the main version information of the Oracle database; 3. Query the PRODUCT_COMPONENT_VERSION view to get the version of each Oracle component; 4. Through the sqlplus-V command, you can view the client or server tool version without logging into the database, but it may not reflect the actual running

TheOracleOptimizerdeterminesthemostefficientwaytoexecuteSQLbyanalyzingexecutionplansbasedonstatisticsandcostestimation.1.Itdecideshowtoaccessdata,includingindexusage,tablejoinorder,andjoinmethods.2.Itestimatescostusingtableandsystemstatistics,andpred

Oraclesequences and identitycolumns can generate self-value-added, but the mechanism is different from the applicable scenarios. 1. Oracle sequences are independent objects that can be used across tables, providing higher control flexibility, such as cache, looping, etc.; 2. The Identity column embeds the self-increment logic in the table column, simplifying the settings, suitable for simple scenarios and closer to MySQL/PostgreSQL usage; 3. The key differences are the scope of action (sequences are available globally, identity columns are limited to single tables), control ability (sequence functions are stronger) and ease of use (identity columns are more intuitive); 4. It is recommended to use identity columns in simple scenarios, and when complex systems or shared counters are required, the sequence is preferred.

Connect to users with DBA permissions; 2. Use the CREATEUSER command to create users and specify necessary parameters; 3. Grant system permissions such as CREATESSION, CREATETABLE, etc. or use CONNECT and RESOURCE roles; 4. Grant additional permissions such as CREATEPROCEDURE or UNLIMITEDTABLESPACE as needed; 5. Optionally grant object permissions to other user objects; 6. Verify user login, the entire process needs to ensure that it is executed in the correct container and follow the principle of minimum permissions, use a strong password policy, and finally complete Oracle user creation and permission allocation.

OracleSQL's CASE statement is used to implement conditional logic in queries, supporting two forms: 1. Simple CASE is used to compare a single expression with multiple values, such as returning department names according to department_id; 2. Search CASE is used to evaluate multiple boolean conditions, suitable for scope or complex logic, such as classified by salary level; 3. CASE can be used in SELECT, ORDERBY, WHERE (indirect), GROUPBY and HAVING clauses to implement data conversion, sorting, filtering, and grouping; 4. Best practices include always using ELSE to prevent NULL, ensure ending in END, adding alias to the result columns, and avoiding excessive nesting; 5. Compared with the old DECOD

Thelistener.orafileisessentialforconfiguringtheOracleNetListenertoacceptandrouteclientconnectionrequests;itdefineslisteningaddressesandports,specifiesdatabaseservicesviastaticregistration,andsetslistenerparameterslikeloggingandtracing;locatedin$ORACL

Usethe||operatortoconcatenatemultiplecolumnsinOracle,asitismorepracticalandflexiblethanCONCAT();2.Addseparatorslikespacesorcommasdirectlywithintheexpressionusingquotes;3.HandleNULLvaluessafelysinceOracletreatsthemasemptystringsduringconcatenation;4.U

To terminate an Oracle session, first query the SID and SERIAL# through the V$SESSION view to locate the target session, and then execute the ALTERSYSTEMKILLSESSION'sid, serial#' command to terminate; if the session does not respond, the IMMEDIATE keyword can be added, and it is only forced to terminate by SPID at the operating system level in extreme cases. It should be noted that the transaction will be rolled back after the session is terminated, so be sure to confirm that the session information is accurate before performing the operation.