- 01Getting Started
- 02SELECT Statement Basics
- 03Filtering Rows with WHERE
- 04Sorting Results with ORDER BY
- 05Combining Tables with JOIN
- 06Aggregating Data with GROUP BY
- 07Fuzzy Matching with LIKE
- 08Modifying Data with INSERT, UPDATE, and DELETE
- 09Introduction to Subqueries
- 10Creating a VIEW
- 11Ranking Rows with Window Functions
- 12Understanding Transactions
- 13Writing Comments in SQL
- 14Logical Operators: AND, OR, NOT
- 15Working with NULL Values
- 16INNER JOIN vs. LEFT JOIN
- 17Filtering Aggregates with HAVING
- 18Removing Duplicates with DISTINCT
- 19Combining Results with UNION
- 20Conditional Values with CASE
- 21Checking Existence with EXISTS
- 22Changing Table Structure with ALTER TABLE
- 23Self Joins
- 24Speeding Up Searches with INDEX
- 25GROUP BY with Multiple Columns
- 26Pagination with LIMIT and OFFSET
- 27Pattern Matching with GLOB
- 28Date Calculations with the date() Function
- 29Joining Three Tables
- 30Matching Multiple Values with IN
- 31Derived Tables: Subqueries in FROM
- 32The Basics of TRIGGER
- 33Readable Queries with WITH (CTEs)
- 34UPSERT: Insert or Update in One Statement
- 35Combining MIN, MAX, and AVG
- 36Restricting Input with CHECK Constraints
- 37Auto-Numbering with AUTOINCREMENT
- 38Inspecting Query Plans with EXPLAIN QUERY PLAN
- 39ORDER BY with Multiple Columns
- 40Conditional Aggregation with CASE
- 41Removing Objects with DROP TABLE and DROP VIEW
- 42Combining Multiple CTEs
- 43Date Range Search with BETWEEN
- 44Finding What's Missing with NOT EXISTS
- 45Substituting NULL with COALESCE
- 46String Functions: UPPER, LENGTH, and SUBSTR
- 47Converting Types with CAST
- 48Merging Grouped Values with GROUP_CONCAT
- 49Enforcing Integrity with FOREIGN KEY
- 50Capstone: Build a Mini Library Management System
Changing Table Structure with ALTER TABLE
This lesson covers changing a table's structure with ALTER TABLE, so you can add a new column to a live database. It's for anyone searching "SQL ALTER TABLE tutorial."
ALTER TABLE table ADD COLUMN name type adds a column after the fact — a routine operation once a system is already running and its data shape needs to grow.
The example starts with a students table that only has id and name, then adds a new grade column with ALTER TABLE students ADD COLUMN grade INTEGER;. Watch how the table's shape changes without any existing data being lost.
A common early mistake is expecting a value in the new column immediately — every existing row gets NULL for a newly added column, so if you need a uniform value everywhere, you have to follow up with an UPDATE. "We need to store one more piece of information" is a request every growing product hears eventually, and being able to change structure without losing existing data is exactly what ALTER TABLE is for.
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