SQL INSERT Statement

Understanding the SQL INSERT Statement

The INSERT statement is used to add new rows of data into a table. It's one of the fundamental Data Manipulation Language (DML) commands that allows you to populate your database with data.

Basic Syntax

Common SQL INSERT Interview Questions

How do you insert a single row into a table?
How can you insert multiple rows at once?
What happens if you don't specify all columns?
How do you handle NULL values in INSERT statements?

SQL INSERT Variations

1. Single Row Insert

Insert a single row by specifying the columns and their values.

2. Multiple Row Insert

Insert multiple rows in a single statement for better performance.

3. Handling NULL Values

You can explicitly insert NULL or omit optional columns.

Practical INSERT Examples

Example 1: Complete User Registration Flow

This example shows how to insert a new user and their first video:

Example 2: Batch Insert with Different Types

This example demonstrates how to insert multiple rows with different interaction types:

Best Practices for SQL INSERT

1. Always Specify Columns

Always explicitly list the columns you're inserting into. This makes your queries more maintainable and protects against schema changes.

2. Use Batch Inserts

When inserting multiple rows, use a single INSERT statement with multiple VALUE sets rather than multiple separate INSERT statements.

3. Validate Data Before Inserting

Ensure your data meets the table's constraints and business rules before attempting to insert. This includes checking for:

Required fields (NOT NULL constraints)
Valid data types
Unique values for keys
Valid foreign key references

4. Use Transactions for Related Inserts

When inserting related data across multiple tables, wrap the inserts in a transaction to ensure data consistency.

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