Interview Questions and Answers

SQL query for joining two tables

• Use the JOIN keyword to combine rows from two or more tables based on a related column between them

• Specify the columns to be retrieved using SELECT statement

• Use ON keyword to specify the join condition

Reverse a given string

• Use a loop to iterate through the characters of the string and build a new string in reverse order

• Alternatively, you can use built-in functions like reverse() or StringBuilder in some programming languages

Delete removes rows from a table while truncate removes all rows from a table without logging individual row deletions.

• Delete is a DML command while truncate is a DDL command.

• Delete can be rolled back while truncate cannot be rolled back.

• Delete triggers delete triggers and delete constraints while truncate does not trigger them.

• Delete is slower than truncate as it logs individual row deletions.

• Example: DELETE FROM table_name WHERE condition;

• Example: TRUNCATE TABLE table_name;

Relationships define how tables are related, joins combine data from two or more tables, and blending combines data from different data sources.

• Relationships are defined in the database schema and determine how tables are related to each other.

• Joins are used to combine data from two or more tables based on a common column or key.

• Blending is used to combine data from different data sources, such as Excel spreadsheets or CSV files.

• Relationships and joins are used in SQL queries...read more