Which is the better way to insert data in another table or mapping table using SQL

Question

Aryan Kumar · Answer

The approach to insert data into another table or a mapping table in SQL depends on the specific requirements and the relationships between the tables. Here are two common methods:

1. Using INSERT INTO ... SELECT:

This method is suitable when you want to copy data from one table to another, possibly with some modifications. It's also helpful when dealing with mapping tables.

Example:

INSERT INTO destination_table (column1, column2, ...)
SELECT column1, column2, ...
FROM source_table
WHERE condition; -- Optional: specify a condition to filter rows

This approach is straightforward and efficient for copying data between tables. It's also useful for creating mapping tables.

2. Using INSERT INTO ... VALUES:

This method is suitable when you have specific values to insert into the destination table.

Example:

INSERT INTO destination_table (column1, column2, ...)
VALUES (value1, value2, ...),
       (value1, value2, ...),
       ...;

This approach is useful when you know the exact values to be inserted. It's often used for smaller datasets or when the data doesn't come directly from another table.

Choosing the Right Method:

If you are copying a large amount of data from one table to another or if you want to filter the data before insertion, the INSERT INTO ... SELECT approach is usually more efficient.

If you are inserting a small number of specific rows, and you already know the values, the INSERT INTO ... VALUES approach might be more concise.

For Mapping Tables:

When dealing with mapping tables (also known as junction tables for many-to-many relationships), the INSERT INTO ... VALUES approach is commonly used, especially when you need to create associations between existing records.

Example for a Mapping Table:

INSERT INTO user_role_mapping (user_id, role_id)
VALUES (1, 101),
       (1, 102),
       (2, 101),
       ...;

In this example, user_role_mapping is a mapping table that associates users with roles.

Choose the method based on the specific requirements of your task, the volume of data, and whether you are working with existing data or specific values. Both methods are valid and widely used in different scenarios.

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Which is the better way to insert data in another table or mapping table using SQL

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1 Answers

1. Using INSERT INTO ... SELECT:

2. Using INSERT INTO ... VALUES:

Choosing the Right Method:

For Mapping Tables: