Altimetrik Interview Questions, Process, and Tips

Implementing incremental load in a table involves updating only new or changed data without reloading the entire dataset.

• Identify a column in the table that can be used to track changes, such as a timestamp or a version number

• Use this column to filter out only the new or updated records during each load

• Merge the new data with the existing data in the table using SQL queries or ETL tools

• Ensure data integrity by handling...read more

Use SQL query to find columns with timestamp data type in a table.

• Use a SQL query like 'SHOW COLUMNS FROM table_name WHERE Type = 'timestamp''

• Alternatively, query the information_schema.columns table for column data types

• Check for variations of timestamp data types like datetime, timestamp, etc.

To delete a column from a table, use the ALTER TABLE command.

• Use the ALTER TABLE command followed by DROP COLUMN to delete a column from a table.

• Specify the name of the column you want to delete after the DROP COLUMN keyword.

• Make sure to carefully consider the impact of deleting a column on the data and any dependent objects.

Drop removes a table from the database, truncate removes all rows from a table, and delete removes specific rows from a table.

• DROP: Removes the entire table structure and data from the database.

• TRUNCATE: Removes all rows from a table but keeps the table structure.

• DELETE: Removes specific rows from a table based on a condition.

• Example: DROP TABLE table_name;

• Example: TRUNCATE TABLE table_name;

• Example: DELETE FROM table_n

Top is used to select the first few rows from a dataset, while limit is used to restrict the number of rows returned in a query.

• Top is commonly used in SQL Server, while limit is commonly used in MySQL.

• Top is used with the SELECT statement in SQL Server to limit the number of rows returned, while limit is used in MySQL to restrict the number of rows returned.

• Example: SELECT TOP 5 * FROM table_name; (SQL Server) vs. SEL

count(*) counts all rows in a table, while count(1) counts the number of non-null values in a specific column.

• count(*) counts all rows in a table

• count(1) counts the number of non-null values in a specific column

• count(*) is generally used when you want to count all rows in a table, while count(1) is used when you want to count non-null values in a specific column

Find the second index of 'l' in the string 'Hello'.

• Use the find() method to find the first index of 'l'.

• Use the find() method again starting from the index after the first 'l' to find the second index.

• Handle cases where the first 'l' is not found or there is no second 'l'.