INSERT INTO single row in MySQL

Introduction

We use INSERT INTO to add new information into a table, one row at a time. It helps us save new data in the database.

Adding a new customer to a customer list.

Saving a new order placed by a buyer.

Recording a new employee's details in the company database.

Entering a new product into the inventory.

Logging a new event or transaction.

Syntax

MySQL

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

Make sure the values match the order and type of the columns.

If you insert all columns, you can skip the column list.

Examples

Adds one user named Alice, age 30, living in New York.

MySQL

INSERT INTO users (name, age, city) VALUES ('Alice', 30, 'New York');

Adds a product with id 101, name Pen, price 1.5 assuming the table has exactly these columns in order.

MySQL

INSERT INTO products VALUES (101, 'Pen', 1.5);

Adds an employee with id 5 and name John. Other columns get default or NULL values.

MySQL

INSERT INTO employees (id, name) VALUES (5, 'John');

Sample Program

This creates a table named books, inserts one book row, then shows all rows in the table.

MySQL

CREATE TABLE books (id INT, title VARCHAR(50), author VARCHAR(50));
INSERT INTO books (id, title, author) VALUES (1, '1984', 'George Orwell');
SELECT * FROM books;

Important Notes

If you forget a column that does not allow NULL or has no default, the insert will fail.

Text values must be in single quotes.

Use SELECT to check if your row was added.

Summary

INSERT INTO adds one new row to a table.

Specify columns and matching values inside parentheses.

Always check your data types and quotes for text.

Practice

1. What does the INSERT INTO statement do in MySQL?

easy

A. Creates a new table

B. Deletes a row from a table

C. Adds a new row to a table

D. Updates existing rows in a table

Solution

1. Step 1: Understand the purpose of INSERT INTO

   The INSERT INTO statement is used to add new data rows into an existing table.

2. Step 2: Compare with other SQL commands

   Deleting removes rows, updating changes existing rows, and creating makes new tables, so these are different commands.

3. Final Answer:

   Adds a new row to a table -> Option C

4. Quick Check:

   INSERT INTO = Add row [OK]

Hint: INSERT INTO always adds new rows, not deletes or updates [OK]

Common Mistakes:

• Confusing INSERT with DELETE or UPDATE
• Thinking INSERT creates tables
• Assuming INSERT modifies existing rows

2. Which of the following is the correct syntax to insert a single row into a table named users with columns id and name?

easy

A. INSERT users INTO (id, name) VALUES (1, 'Alice');

B. INSERT INTO users (id, name) VALUES (1, 'Alice');

C. INSERT INTO users VALUES id=1, name='Alice';

D. INSERT INTO users (id, name) SET (1, 'Alice');

Solution

1. Step 1: Check the standard INSERT INTO syntax

   The correct syntax is INSERT INTO table_name (columns) VALUES (values); which matches INSERT INTO users (id, name) VALUES (1, 'Alice');.

2. Step 2: Identify errors in other options

   INSERT users INTO (id, name) VALUES (1, 'Alice'); has wrong order of keywords, C uses invalid assignment syntax, and D uses SET incorrectly.

3. Final Answer:

   INSERT INTO users (id, name) VALUES (1, 'Alice'); -> Option B

4. Quick Check:

   INSERT INTO ... VALUES (...) is correct syntax [OK]

Hint: Remember: INSERT INTO table (cols) VALUES (vals); [OK]

Common Mistakes:

• Swapping keywords order
• Using SET instead of VALUES
• Incorrect assignment inside VALUES

3. Given the table products(id INT, name VARCHAR(20), price DECIMAL(5,2)), what will be the result of this query?
INSERT INTO products (id, name, price) VALUES (10, 'Pen', 1.50); SELECT * FROM products WHERE id = 10;

medium

A. [{"id":10, "name":"Pen", "price":1.50}]

B. Syntax error due to missing semicolon

C. Empty result, no rows inserted

D. [{"id":null, "name":"Pen", "price":1.50}]

Solution

1. Step 1: Analyze the INSERT statement

   The query inserts a row with id=10, name='Pen', price=1.50 into the products table.

2. Step 2: Check the SELECT query result

   The SELECT fetches the row with id=10, which was just inserted, so it returns that row.

3. Final Answer:

   [{"id":10, "name":"Pen", "price":1.50}] -> Option A

4. Quick Check:

   Inserted row is returned by SELECT [OK]

Hint: Inserted row appears in SELECT immediately after insert [OK]

Common Mistakes:

• Assuming insert fails without error
• Expecting empty result after insert
• Confusing syntax errors with correct queries

4. Identify the error in this query:
INSERT INTO employees (id, name, salary) VALUES (5, John, 3000);

medium

A. Salary should be a string

B. Missing parentheses around VALUES

C. Wrong table name

D. Missing quotes around the string 'John'

Solution

1. Step 1: Check string value syntax

   String values like names must be enclosed in single quotes in SQL, but 'John' is unquoted here.

2. Step 2: Verify other parts of the query

   Parentheses around VALUES are correct, table name is plausible, and salary is numeric so no quotes needed.

3. Final Answer:

   Missing quotes around the string 'John' -> Option D

4. Quick Check:

   Strings need quotes in VALUES [OK]

Hint: Always quote text values in INSERT [OK]

Common Mistakes:

• Forgetting quotes for text
• Confusing numeric and string types
• Misplacing parentheses

5. You have a table orders(order_id INT, customer VARCHAR(50), total DECIMAL(7,2)). You want to insert a new order with order_id 101, customer name "O'Reilly", and total 250.75. Which query correctly inserts this row?

hard

A. INSERT INTO orders (order_id, customer, total) VALUES (101, 'O''Reilly', 250.75);

B. INSERT INTO orders (order_id, customer, total) VALUES (101, 'O\'Reilly', 250.75);

C. INSERT INTO orders (order_id, customer, total) VALUES (101, 'O'Reilly', 250.75);

D. INSERT INTO orders (order_id, customer, total) VALUES (101, "O'Reilly", 250.75);

Solution

1. Step 1: Understand how to escape single quotes in SQL strings

   In SQL, single quotes inside strings are escaped by doubling them: 'O''Reilly'.

2. Step 2: Evaluate each option's string quoting

   INSERT INTO orders (order_id, customer, total) VALUES (101, 'O'Reilly', 250.75); breaks string due to unescaped single quote. INSERT INTO orders (order_id, customer, total) VALUES (101, 'O\'Reilly', 250.75); uses backslash which is not standard in MySQL. INSERT INTO orders (order_id, customer, total) VALUES (101, "O'Reilly", 250.75); uses double quotes which are not string delimiters in SQL. INSERT INTO orders (order_id, customer, total) VALUES (101, 'O''Reilly', 250.75); correctly doubles the single quote.

3. Final Answer:

   INSERT INTO orders (order_id, customer, total) VALUES (101, 'O''Reilly', 250.75); -> Option A

4. Quick Check:

   Escape single quote by doubling it [OK]

Hint: Escape single quote inside strings by doubling it '' [OK]

Common Mistakes:

• Using unescaped single quotes inside strings
• Using backslash escape in MySQL strings
• Using double quotes for string literals