Kiran P has Published 125 Answers

How to gather extended query execution stats in Oracle?

Kiran P
Published on 05-Dec-2020 05:52:55
Problem:You want to gather extended explain plan statistics for a specific query.SolutionWe can use the GATHER_PLAN_STATISTICS hint. This hint when placed within a query at runtime, will generate extended runtime statistics. It basically have two steps.Execute the query with the gather_plan_statistics hint.Use dbms_xplan.display_cursor to display the results.ExampleSELECT /*+ gather_plan_statistics */ ... Read More

How to change the JOIN Method in Oracle ?

Kiran P
Published on 05-Dec-2020 05:49:23
Problem:You have a performance issue with a queryhaving JOIN conditions on multiple tables, and you wish to override the join type by placing the appropriate hint in the query.Solution:There are three possible types of joins: nested loops, hash, and sort merge.Nested Loops Join Hint:  To invoke a nested loops join, ... Read More

How to change the JOIN order in Oracle?

Kiran P
Published on 04-Dec-2020 11:07:18
Problem:You have a performance issue with a queryhaving JOIN conditions on multiple tables, and the Oracle optimizer is not choosing the join order you wanted.Solution:Oracle has two hints the ORDERED hint, and the LEADING hint that can be used to influence the join order used within a query.ORDERED HintYou are ... Read More

How to generate a data model from data dictionary tables in Oracle?

Kiran P
Published on 04-Dec-2020 11:05:43
Problem:You wanted to generate a data model from data dictionary tables in OracleSolution:The Oracle data dictionary is a collection of tables and related views that enable us to view the structure of the Oracle database. By querying these tables and views, we can obtain information about every object and every ... Read More

How to generate data with Union ALL and Insert ALL in Oracle?

Kiran P
Published on 04-Dec-2020 11:02:22
Problem:You wanted to know the difference between Union ALL and Insert ALL to generate small amounts of data.Solution:I have been recently generating small amounts of data for testing some functionality and came across a couple of options in Oracle. Union All and Insert All are two options commonly used for ... Read More

How to detect if a given year is a Leap year in Oracle?

Kiran P
Published on 04-Dec-2020 11:00:47
Problem:You need to determine if any given year is a leap year.Solution:There are numerous ways of solving this problem.These include calculations to determine whether February 29 exists in the year, or whether March 1 is the 61st or 62nd day of the year.ExampleSELECT to_number(to_char(sysdate, 'YYYY')) Year,   CASE     ... Read More

How to view storage configuration of Oracle database?

Kiran P
Published on 04-Dec-2020 10:59:35
Problem:You want to find out some indroductory information about the database.Solution:Every Oracle programmer/ DBA has at one point or another during their career inherited a database someone else have already set up.You needs to find out some introductory information about the database to learn more about it.Idenitfy the host details ... Read More

How to access values from previous or following rows in Oracle ?

Kiran P
Published on 04-Dec-2020 10:58:19
You want to use Oracle aggregate function XMLAGG for string aggregation.?Solution:You would like to include calculations based on preceding and following rows in the result set.Oracle supports the LAG and LEAD analytical functions to provide access to multiple rows in a table, utilizing preceding or following logic and you won’t ... Read More

How to use Oracle aggregate function XMLAGG ?

Kiran P
Published on 04-Dec-2020 10:54:05
You want to use Oracle aggregate function XMLAGG for string aggregation.?Solution:ExampleSELECT class_id,   rtrim(xmlagg(xmlelement(x, first_name   || ' '   || last_name , ', ') ORDER BY first_name).extract('//text()').getstringval(), ', ') AS "names" FROM students GROUP BY class_id;OutputCL_MATH         ANDERSON DANIEL, MARTINEZ CHRISTOPHER, TAYLOR PAUL, THOMAS MARK, WILSON ... Read More

How to perform string aggregation/concatenation in Oracle?

Kiran P
Published on 04-Dec-2020 10:52:16
Problem Statement:You want to perform string concatenation as a comma delimited text in oracle.Solution:Oracle has few methods to perform string aggregation. The most common usuage you popularly find on internet is to convert multiple rows to a single row with a delimiter.Starting Oracle version 11.2, a new built-in function is ... Read More
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