Four SQL Questions
interview questions on SQL
1.What is SQL?
The acronym SQL stands for Structured Query Language. It is the typical language used for relational database maintenance and a wide range of data processing tasks. The first SQL database was created in 1970. It is a database language used for operations such database creation, deletion, retrieval, and row modification. It is occasionally pronounced "sequel." It may also be used to manage structured data, which is made up of variables called entities and relationships between those entities.
2.What is RDBMS?
Relational Database Management System is referred to as RDBMS. It is a relational model-based database management system. Using relational operators makes it easier to alter the data that is contained in the tables. RDBMS maintains the data in a group of tables and quickly ties those tables together as needed using relational operators. Microsoft Access, MySQL, SQL Server, Oracle database, and other programs are instances of relational database management systems.
3. What is NVL() function?
The NULL value is changed to the other value using the NVL() function. If the first parameter is NULL, the function returns the value of the second parameter. It is left unaltered if the first parameter is anything other than NULL. Not in SQL or MySQL, but in Oracle, this function is utilized. MySQL has the IFNULL() function and SQL Server has the ISNULL() function in place of the NVL() function.
Is it possible to implicitly insert a row for the identity column?
Yes. We can implicitly insert a row for the identity column. Here is an example of doing this:
SET IDENTITY_INSERT TABLE1 ON
INSERT INTO demo_table1 (id, name, branch)
SELECT id, name, branch FROM demo_table2
SET IDENTITY_INSERT OFF
