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SQL Articles
Page 9 of 12
Sqoop Integration with Hadoop Ecosystem
Data was previously stored in relational data management systems when Hadoop and big data concepts were not available. After introducing Big Data concepts, it was essential to store the data more concisely and efficiently. However all data stored in the related data management system needs to be transferred to the Hadoop archive. With Sqoop, we can transfer this amount of personal data. Sqoop transfers data from a related database management system to a Hadoop server. Thus, it facilitates the transfer of large volumes of data from one source to another. Here are the basic features of Sqoop − Sqoop ...
Read MoreDifference between Delete and truncate in sql query
Both the TRUNCATE statement and the DELETE statement are included in the category of SQL queries for deleting the data stored in a table. They carry out deletion operations on records or rows of a table that are no longer needed. A condition is applied before each entry in the table that is being deleted when using the DELETE command. To put it another way, it is possible to delete one or more rows all at once. However, with the TRUNCATE command, each row is removed from the table simultaneously. When we delete something using the DELETE query, a log ...
Read MoreDifference between NoSQL and RDBMS
Most SQL databases are relational. Relational Databases are tabular and have a pre-determined schema that organizes the data logically. Database management solutions have evolved from the classic relational paradigm to the more flexible and scalable NoSQL approach.Some say NoSQL stands for "non-SQL, " but many refer to it as SQL. NoSQL is a non-relational database management system for certain data models. These data models don't need a schema and are scalable. It offers a system-supported alternative to relational databases' tabular format for storing and retrieving data. NoSQL databases don't require a certain schema. You can store data without worrying about ...
Read MoreFloyd's triangle in PL/SQL
PL/SQL is a combination of SQL along with the procedural features of programming languagesFLOYD’s triangle − it is a triangle formed by natural numbers. It is the triangle formed by filling numbers in rows starting from 1 at the top-left corner. It is a right-angled triangle i.e. the count of numbers in each row is the same as the row number.In this problem, we are given a natural number N. Our task is to create Floyd’s triangle in PL/SQL.Let’s take an example to understand the problemInput: 16 Output: 1 2 3 4 5 6 7 8 9 10 11 12 ...
Read MoreFinding sum of first n natural numbers in PL/SQL
In this problem, we are given a number N. Our task is to finding sum of first n natural numbers in PL/SQL.PL/SQL is a combination of SQL along with the procedural features of programming languages.PL/SQL has the following features −PL/SQL is tightly integrated with SQL.It offers extensive error checking.It offers numerous data types.It offers a variety of programming structures.It supports structured programming through functions and procedures.It supports object-oriented programming.It supports the development of web applications and server pages.PL/SQL has the following advantages −SQL is the standard database language and PL/SQL is strongly integrated with SQL. PL/SQL supports both static and ...
Read MoreFind the area and perimeter of right triangle in PL/SQL
In this problem, we are given three values: base, height and hypotenuse of a right triangle. Our task is to find the area and perimeter of the right triangle in PL/SQL.PL/SQL is a combination of SQL along with the procedural features of programming languagesLet's take an example to understand the problem, Input : height = 4, base = 3, hypotenuse = 5 Output : area = 6, perimeter = 12Explanation −1 + 22 + 333 + 4444 = 4800 Solution ApproachA simple approach to solve the problem is using the formula for the area and perimeter of the triangle.Area = ...
Read MoreDifference Between ROLAP and MOLAP
In this post, we will understand the difference between ROLAP and MOLAP.ROLAPIt stands for Relational Online Analytical Processing.It is used for large volumes of data.The access time in ROLAP is slow.It stores data in the form of relation tables.The data in ROLAP is fetched from a data warehouse.It uses complex SQL queries.A static multidimensional view of the data is created in ROLAP.MOLAPIt stands for Multidimensional Online Analytical Processing.It is used for less/limited volumes of data.The access time is quick in MOLAP.Data is stored in a multidimensional array.Data is fetched from the MDDBs database.A sparse matrix is used in MOLAP.Dynamic multidimensional ...
Read MoreWhat is the purpose of OPTIMIZE FOR ROWS in DB2 SQLs? How is it useful?
The OPTIMIZE FOR N ROWS is a DB2 clause which we can add in the query to give priority for the retrieval of the first few rows only. This clause will enable the optimizer to choose the access path that minimizes the response time for fetching first few rows.The OPTIMIZE FOR N ROWS clause is not effective on SELECT DISTINCT and COUNT function because DB2 will need the entire qualifying rows in order to fetch the DISTINCT rows or COUNT the number of rows. The OPTIMIZE FOR N ROWS clause gives DB2 a better opportunity to establish the access path.The ...
Read MoreWrite a SQL query to count the number of duplicate TRANSACTION_ID in an ORDERS DB2 table
We can find the duplicate TRANSACTION_ID in the ORDERS DB2 table using the below query:ExampleSELECT TRANSACTION_ID, COUNT(*) AS TRANSACTION_COUNT FROM ORDER GROUP BY TRANSACTION_ID HAVING COUNT(*) > 1The purpose of COUNT(*) is to count the number of rows. We will group the result based on the TRANSACTION_ID using GROUP BY function and to display the duplicate transaction ids, we will place a predicate using HAVING statement for COUNT(*) greater than one.For example, consider the below TRANSACTIONS DB2 table:TRANSACTION_IDTRANSACTION_STATUSIRN22345PAIDIRN22345PAIDIRN22345PAIDIRN56902PAIDIRN99781UNPAIDIRN56902PAIDThe query will give the below result:TRANSACTION_IDTRANSACTION_COUNTIRN223453IRN569022IRN997811
Read MoreExplain SQL describing COUNT aggregate and CURRENT DATE function
Problem: Write a SQL query to count the number of orders which were placed today from the ORDERS DB2 table. (The date should not be hardcoded)SolutionWe can find the count of orders which are placed today using the below DB2 query:ExampleSELECT COUNT(ORDER_ID) AS ORDER_COUNT FROM ORDERS WHERE ORDER_DATE = CURRENT DATEIn this query, we have used the COUNT COLUMN function which will count the total number of ORDER_ID (primary key). In the WHERE clause, we will use the predicate for the ORDER_DATE column. The CURRENT DATE is a DB2 inbuilt function which will return the current system date.For example, if ...
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