PostgreSQL Insert Data

PostgreSQL Tutorial

PostgreSQL INSERT Data

In PostgreSQL, the INSERT statement is used to add new records (rows) into a table.
This is one of the most important SQL operations and is frequently asked in interviews.

What is INSERT in PostgreSQL?

The INSERT INTO statement:

  • Adds new rows to a table

  • Can insert single or multiple records

  • Can insert data from another table (INSERT SELECT)

Basic INSERT Syntax

Example Table

How to Insert Data

  • Inserts one record
  • id is auto-generated because of SERIAL

Ways to Insert Multiple Rows at Once

  • Faster than multiple single inserts
  •  Interview favorite

Insert Without Column Names (Not Recommended)

  •  Column order must match table structure
  • Avoid this in real projects

Insert Partial Data (NULL Values)

  •  Missing columns become NULL
  • Works only if column allows NULL

Using DEFAULT Values While Inserting Data

  •  Uses column default value

INSERT Using SELECT (Advanced)

  • Copies data from another table
  • Very common in data migration

RETURNING Clause (PostgreSQL Special)

  •  Returns generated ID
  • PostgreSQL-specific feature
  • Interview bonus point

 Check Inserted Data

Common INSERT Errors

  •  Column/value count mismatch
  •  Data type mismatch
  •  Violating NOT NULL / UNIQUE constraint
  •  Forgetting quotes for strings

Interview Questions & MCQs

Q1. Which command is used to insert data?

A) ADD
B) INSERT
C) PUT
D) UPDATE

Answer: B

Q2. How to insert multiple rows?

A) Multiple INSERT statements
B) VALUES with commas
C) UPDATE
D) JOIN

Answer: B

Q3. Which PostgreSQL feature returns inserted ID?

A) LAST_ID
B) AUTO_ID
C) RETURNING
D) SERIAL

Answer: C

Q4. If column is missing in INSERT?

A) Error always
B) Gets NULL
C) Gets 0
D) Gets ignored

Answer: B (if NULL allowed)

Q5. Is INSERT SELECT allowed in PostgreSQL?

A) Yes
B) No

Answer: A

Real-Life Use Cases

  •  User registration
  •  Order creation
  •  Log storage
  •  Data migration
  •  API backends

Summary

  • Use INSERT INTO to add data

  • Supports single & multiple inserts

  • SERIAL auto-generates IDs

  • RETURNING is PostgreSQL-specific

  • INSERT SELECT useful for migrations

  • Core topic for PostgreSQL exams & interviews

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