PL/SQL stands for Procedural Language extension of SQL. PL/SQL is a combination of SQL along with the procedural features of programming languages. It was developed by Oracle Corporation in the early ...

SELECT SUBSTR('Oracle SQL', 1, 6); -- → Oracle (start at 1, take 6 chars) SELECT SUBSTR('Oracle SQL', 8, 3); -- → SQL (start at 8, take 3 chars) SELECT SUBSTR ...

SELECT COUNT(Marks) FROM Student; -- → 6 (RAHUL has NULL Marks, excluded) SELECT COUNT(Age) FROM Student; -- → 6 (RAHUL has NULL Age, excluded) -- COUNT with WHERE: counts rows matching a condition ...