1) Given the View, which of the following statements are valid? CREATE VIEW DEPT_SUMMARY (D, C, TOTAL_S, AVERAGE_S) AS SELECT DNO, COUNT(*), SUM(SALARY), AVG(SALARY) FROM EMPLOYEE GROUP BY DNO; --- which of the following is allowed? -- A SELECT * FROM DEPT_SUMMARY; -- B SELECT D, C FROM DEPT_SUMMARY WHERE TOTAL_S > 100000; -- C SELECT D, AVERAGE_S FROM DEPT_SUMMARY WHERE C > ( SELECT C FROM DEPT_SUMMARY WHERE D = 4); -- D UPDATE DEPT_SUMMARY SET D = 3 WHERE D = 4; -- E DELETE FROM DEPT_SUMMARY WHERE C > 4;
SQL
SQL stands for Structured Query Language, is a form of communication that uses queries structured in a specific format to store, manage & retrieve data from a relational database.
Queries
A query is a type of computer programming language that is used to retrieve data from a database. Databases are useful in a variety of ways. They enable the retrieval of records or parts of records, as well as the performance of various calculations prior to displaying the results. A search query is one type of query that many people perform several times per day. A search query is executed every time you use a search engine to find something. When you press the Enter key, the keywords are sent to the search engine, where they are processed by an algorithm that retrieves related results from the search index. Your query's results are displayed on a search engine results page, or SER.
1) Given the View, which of the following statements are valid?
CREATE VIEW DEPT_SUMMARY (D, C, TOTAL_S, AVERAGE_S)
AS SELECT DNO, COUNT(*), SUM(SALARY), AVG(SALARY)
FROM EMPLOYEE
GROUP BY DNO; --- which of the following is allowed?
-- A
SELECT * FROM DEPT_SUMMARY;
-- B
SELECT D, C FROM DEPT_SUMMARY WHERE TOTAL_S > 100000;
-- C
SELECT D, AVERAGE_S FROM DEPT_SUMMARY WHERE C > ( SELECT C FROM DEPT_SUMMARY WHERE D = 4);
-- D
UPDATE DEPT_SUMMARY SET D = 3 WHERE D = 4;
-- E
DELETE FROM DEPT_SUMMARY WHERE C > 4;
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