Inserting Data

Once you have created a database and defined tables, you can add actual data into those tables.

In MySQL, this is done using the INSERT INTO statement.

Basic Syntax

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);

• table_name: the name of the table you are adding data to
• (column1, column2, ...): the list of columns to insert data into
• VALUES: the actual values to be stored

Each set of values represents one row of data in the table.

Example Table: students

Assume we have this table:

CREATE TABLE students (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  age INT,
  email VARCHAR(150),
  enrollment_date DATE
);

Example: Inserting One Row

INSERT INTO students (id, name, age, email, enrollment_date)
VALUES (1, 'Alice Smith', 20, 'alice@example.com', '2025-06-23');

This adds a new student record to the table.

Inserting Multiple Rows

You can insert multiple rows in one command:

INSERT INTO students (id, name, age, email, enrollment_date)
VALUES
  (2, 'Bob Johnson', 22, 'bob@example.com', '2025-06-20'),
  (3, 'Carol Thomas', 19, 'carol@example.com', '2025-06-21');

Viewing Inserted Data

After inserting data, you can check the contents of the table using:

SELECT * FROM students;

This displays all rows and columns from the students table.

Important Notes

• The order of columns in the INSERT INTO clause must match the order of values provided.

• All required columns (non-nullable columns, such as PRIMARY KEY) must be included.

• The data must match the correct data type for each column:

  • Numbers (INT, DECIMAL)
  • Strings (VARCHAR, TEXT) must be in quotes '...'
  • Dates must be in the format 'YYYY-MM-DD'

Example: Common Mistake

Incorrect: mixing up column order:

-- Wrong order, will cause error
INSERT INTO students (name, id, age, email, enrollment_date)
VALUES ('Dan Green', 4, 21, 'dan@example.com', '2025-06-22');

Correct: match columns to values properly:

INSERT INTO students (id, name, age, email, enrollment_date)
VALUES (4, 'Dan Green', 21, 'dan@example.com', '2025-06-22');

Summary

• INSERT INTO adds new rows of data to a table.
• You must specify which columns and which values to insert.
• Values must match the column data types.
• You can insert one row or multiple rows at a time.
• After inserting, use SELECT to view the data.