SQL String Concatenation with CONCAT

In database management, it's often necessary to combine multiple string values into a single, cohesive string. This is a common operation for generating formatted reports, creating unique identifiers, or presenting user-friendly messages. This challenge focuses on using the CONCAT function in SQL to achieve this.

Problem Description

Your task is to write a SQL query that concatenates strings from multiple columns within a table, along with a specified separator. You will be provided with a table containing customer information, and you need to create a new column that represents the full name of each customer.

What needs to be achieved: Combine the first_name and last_name columns from a customers table into a single full_name column, separated by a single space.

Key requirements:

Use the CONCAT function for string concatenation.
The separator between the first and last name should be a single space.
The query should return all columns from the original customers table, plus the new full_name column.

Expected behavior: For each row in the customers table, the full_name should be constructed by taking the first_name, appending a space, and then appending the last_name.

Edge cases to consider:

What happens if a first_name or last_name is NULL? The CONCAT function's behavior with NULL values can vary between SQL dialects. For this challenge, assume that if either first_name or last_name is NULL, the resulting full_name should also be NULL.

Examples

Example 1: Input Table: customers

customer_id	first_name	last_name	email
1	Alice	Smith	alice.smith@email.com
2	Bob	Johnson	bob.j@email.com

Output:

customer_id	first_name	last_name	email	full_name
1	Alice	Smith	alice.smith@email.com	Alice Smith
2	Bob	Johnson	bob.j@email.com	Bob Johnson

Explanation: The full_name for customer ID 1 is created by concatenating 'Alice', a space, and 'Smith'. The full_name for customer ID 2 is created by concatenating 'Bob', a space, and 'Johnson'.

Example 2: Input Table: customers

customer_id	first_name	last_name	email
3	Charlie	NULL	charlie@email.com
4	NULL	Davis	null.davis@email.com

Output:

customer_id	first_name	last_name	email	full_name
3	Charlie	NULL	charlie@email.com	NULL
4	NULL	Davis	null.davis@email.com	NULL

Explanation: Since last_name is NULL for customer ID 3, the full_name becomes NULL. Similarly, since first_name is NULL for customer ID 4, the full_name becomes NULL.

Constraints

The customers table will contain at least one row.
The customer_id column will be an integer.
The first_name and last_name columns will be of a string data type (e.g., VARCHAR, TEXT).
The query should be performant and execute efficiently on large datasets.

Notes

The specific syntax for CONCAT might differ slightly across SQL databases (e.g., MySQL, PostgreSQL, SQL Server). For this challenge, assume a standard CONCAT(string1, string2, ...) function signature.
Consider how your chosen SQL dialect handles NULL values with CONCAT. If your dialect's CONCAT function ignores NULL values by default, you might need to use an alternative or a helper function like COALESCE to achieve the desired behavior of returning NULL if any part is NULL. However, for the primary solution, aim for the most direct CONCAT usage that aligns with the NULL handling described.

SQL String Concatenation with CONCAT

Problem Description

What needs to be achieved: Combine the first_name and last_name columns from a customers table into a single full_name column, separated by a single space.

Key requirements:

Use the CONCAT function for string concatenation.
The separator between the first and last name should be a single space.
The query should return all columns from the original customers table, plus the new full_name column.

Expected behavior: For each row in the customers table, the full_name should be constructed by taking the first_name, appending a space, and then appending the last_name.

Edge cases to consider:

What happens if a first_name or last_name is NULL? The CONCAT function's behavior with NULL values can vary between SQL dialects. For this challenge, assume that if either first_name or last_name is NULL, the resulting full_name should also be NULL.

Examples

Example 1: Input Table: customers

customer_id	first_name	last_name	email
1	Alice	Smith	alice.smith@email.com
2	Bob	Johnson	bob.j@email.com

Output:

customer_id	first_name	last_name	email	full_name
1	Alice	Smith	alice.smith@email.com	Alice Smith
2	Bob	Johnson	bob.j@email.com	Bob Johnson

Explanation: The full_name for customer ID 1 is created by concatenating 'Alice', a space, and 'Smith'. The full_name for customer ID 2 is created by concatenating 'Bob', a space, and 'Johnson'.

Example 2: Input Table: customers

customer_id	first_name	last_name	email
3	Charlie	NULL	charlie@email.com
4	NULL	Davis	null.davis@email.com

Output:

customer_id	first_name	last_name	email	full_name
3	Charlie	NULL	charlie@email.com	NULL
4	NULL	Davis	null.davis@email.com	NULL

Explanation: Since last_name is NULL for customer ID 3, the full_name becomes NULL. Similarly, since first_name is NULL for customer ID 4, the full_name becomes NULL.

Constraints

The customers table will contain at least one row.
The customer_id column will be an integer.
The first_name and last_name columns will be of a string data type (e.g., VARCHAR, TEXT).
The query should be performant and execute efficiently on large datasets.

Notes

The specific syntax for CONCAT might differ slightly across SQL databases (e.g., MySQL, PostgreSQL, SQL Server). For this challenge, assume a standard CONCAT(string1, string2, ...) function signature.
Consider how your chosen SQL dialect handles NULL values with CONCAT. If your dialect's CONCAT function ignores NULL values by default, you might need to use an alternative or a helper function like COALESCE to achieve the desired behavior of returning NULL if any part is NULL. However, for the primary solution, aim for the most direct CONCAT usage that aligns with the NULL handling described.