INSERT with specific columns in SQL

Introduction

We use INSERT with specific columns to add new data to only certain parts of a table, not all columns. This helps when we don't have values for every column.

When you want to add a new user but only know their name and email, not their phone number.

When inserting a new product with just its name and price, leaving other details empty.

When adding a record where some columns have default values and you don't want to specify them.

When you want to avoid errors by specifying exactly which columns you are filling.

Syntax

SQL

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

You must list columns in the same order as the values you provide.

Columns not listed will get their default value or NULL if allowed.

Examples

Adds a new user with only name and email filled.

SQL

INSERT INTO users (name, email) VALUES ('Alice', '[e-mail]');

Adds a product with name and price, other columns stay default.

SQL

INSERT INTO products (product_name, price) VALUES ('Book', 9.99);

Inserts an employee record specifying only first and last names.

SQL

INSERT INTO employees (first_name, last_name) VALUES ('John', 'Doe');

Sample Program

Creates a students table with four columns. Inserts a student with name and age only. City uses default 'Unknown'. Then selects all rows.

SQL

CREATE TABLE students (
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(50),
  age INT,
  city VARCHAR(50) DEFAULT 'Unknown'
);

INSERT INTO students (name, age) VALUES ('Emma', 20);

SELECT * FROM students;

Important Notes

If you omit columns that do not allow NULL and have no default, the INSERT will fail.

Always check the table schema to know which columns are required.

Using specific columns helps avoid mistakes when table structure changes.

Summary

INSERT with specific columns lets you add data to chosen columns only.

You list columns and matching values in order.

Unlisted columns get default values or NULL if allowed.

Practice

1. What does the SQL statement INSERT INTO employees (name, age) VALUES ('Alice', 30); do?

easy

A. Deletes rows where name is 'Alice' and age is 30.

B. Inserts a new row filling all columns with 'Alice' and 30.

C. Updates existing rows setting name to 'Alice' and age to 30.

D. Inserts a new row with only the name and age columns filled, others get default or NULL.

Solution

1. Step 1: Understand the INSERT with specific columns

   The statement specifies only the columns 'name' and 'age' to insert values into.

2. Step 2: Effect on other columns

   Columns not listed get their default values or NULL if allowed.

3. Final Answer:

   Inserts a new row with only the name and age columns filled, others get default or NULL. -> Option D

4. Quick Check:

   INSERT with columns fills only those columns [OK]

Hint: List columns to insert only those, others get defaults [OK]

Common Mistakes:

• Thinking all columns get values from VALUES list
• Confusing INSERT with UPDATE
• Assuming unlisted columns get random data

2. Which of the following is the correct syntax to insert only the columns id and email into a table users?

easy

A. INSERT INTO users (id, email) VALUES (1, '[e-mail]');

B. INSERT INTO users SET id=1, email='[e-mail]';

C. INSERT users (id, email) VALUES (1, '[e-mail]');

D. INSERT INTO users VALUES (1, '[e-mail]');

Solution

1. Step 1: Identify correct INSERT syntax with specific columns

   The correct syntax requires specifying the table, columns in parentheses, then VALUES with matching values.

2. Step 2: Check each option

   INSERT INTO users (id, email) VALUES (1, '[e-mail]'); matches the correct syntax: INSERT INTO table (columns) VALUES (values).

3. Final Answer:

   INSERT INTO users (id, email) VALUES (1, '[e-mail]'); -> Option A

4. Quick Check:

   INSERT INTO table (cols) VALUES (vals) is correct [OK]

Hint: Use INSERT INTO table (cols) VALUES (vals) format [OK]

Common Mistakes:

• Omitting INTO keyword
• Using SET instead of VALUES
• Not specifying columns when needed

3. Given the table products(id INT, name VARCHAR, price DECIMAL DEFAULT 0), what will be the result of this query?
INSERT INTO products (id, name) VALUES (101, 'Pen');
Then selecting all rows?

medium

A. [{id: 101, name: 'Pen', price: NULL}]

B. [{id: 101, name: 'Pen', price: 0}]

C. [{id: 101, name: 'Pen'}]

D. Syntax error

Solution

1. Step 1: Understand default values on missing columns

   The 'price' column has a default value of 0, so if not specified, it gets 0.

2. Step 2: Result of the INSERT and SELECT

   The inserted row will have id=101, name='Pen', and price=0 from default.

3. Final Answer:

   [{id: 101, name: 'Pen', price: 0}] -> Option B

4. Quick Check:

   Default values fill missing columns [OK]

Hint: Unlisted columns get default values if defined [OK]

Common Mistakes:

• Assuming missing columns become NULL despite default
• Expecting syntax error without all columns
• Ignoring default values

4. Identify the error in this SQL statement:
INSERT INTO orders (order_id, customer) VALUES (123);

medium

A. Missing value for 'customer' column

B. Table name is incorrect

C. VALUES keyword is missing

D. Extra parentheses around columns

Solution

1. Step 1: Check number of columns vs values

   The statement lists two columns but provides only one value.

2. Step 2: Identify mismatch error

   SQL requires the number of values to match the number of columns exactly.

3. Final Answer:

   Missing value for 'customer' column -> Option A

4. Quick Check:

   Columns and values count must match [OK]

Hint: Count columns and values to match [OK]

Common Mistakes:

• Providing fewer values than columns
• Assuming missing values default to NULL always
• Ignoring syntax error messages

5. You have a table students(id INT PRIMARY KEY, name VARCHAR, grade CHAR DEFAULT 'F'). You want to insert a new student with id=5 and name='John', but leave grade as default. Which query is correct?

hard

A. INSERT INTO students (id, name, grade) VALUES (5, 'John', 'F');

B. INSERT INTO students VALUES (5, 'John');

C. INSERT INTO students (id, name) VALUES (5, 'John');

D. INSERT INTO students (name, grade) VALUES ('John', 'F');

Solution

1. Step 1: Understand default column behavior

   Omitting 'grade' column in INSERT lets it use its default 'F'.

2. Step 2: Check each option

   INSERT INTO students (id, name) VALUES (5, 'John'); omits grade, using default. INSERT INTO students (id, name, grade) VALUES (5, 'John', 'F'); sets it explicitly. INSERT INTO students VALUES (5, 'John'); has value count mismatch. INSERT INTO students (name, grade) VALUES ('John', 'F'); misses id primary key.

3. Final Answer:

   INSERT INTO students (id, name) VALUES (5, 'John'); -> Option C

4. Quick Check:

   Omit columns to use default values [OK]

Hint: Omit columns to use their default values [OK]

Common Mistakes:

• Providing all columns when default is desired
• Omitting primary key column causing errors
• Assuming VALUES must match all columns always