Technology Questions

- If the table structure is changed ( a field is added ), the program will have to be modified.

- Program might retrieve the columns which it might not use, leading on I/O over head.

- The chance of an index only scan is lost.

Data cleaning is also known as data scrubbing. Data cleaning is a process which ensures the set of data is correct and accurate. Data accuracy and consistency, data integration is checked during data cleaning. Data cleaning can be applied for a set of records or multiple sets of data which need to be merged.

Data cleaning is performed by reading all records in a set and verifying their accuracy. Typos and spelling errors are rectified. Mislabeled data if available is labeled and filed. Incomplete or missing entries are completed. Unrecoverable records are purged, for not to take space and inefficient operations.

- Rename : It is a permanent name provided to a table or column.
- Alias : It is a temporary name provided to a table or column which gets over after the execution of SQL statement.

Locking is a mechanism to ensure data integrity while allowing maximum concurrent access to data. It is used to implement concurrency control when multiple users access table to manipulate its data at the same time.

Advantages :

- Avoids deadlock conditions

- Avoids clashes in capturing the resources

According to one-definition rule, C++ constructs must be identically defined in every compilation unit they are used in. 

As per ODR, two definitions contained in different source files are called to be identically defined if they token-for-token identical. The tokens should have same meaning in both source files. 

Identically defined doesn’t mean character-by-character equivalence. Two definitions can have different whitespace or comments and yet be identical.

STL stands for Standard Template Library. It is a library of container templates approved by the ANSI committee for inclusion in the standard C++ specification.

A conversion constructor declared with the explicit keyword. The compiler does not use an explicit constructor to implement an implied conversion of types. It’s purpose is reserved explicitly for construction

Recursive query can be create in SQL using stored procedure but you can also use CTE (Common table expression). It might be also worth asking about performance as CTE is not always very fast.