Q.Consider the table ORDERS given below and write the output of the SQL queries that follow: ORDNO ITEM QTY RATE ORDATE 1001 RICE 23 120 2023-09-10 1002 PULSES 13 120 2023-10-18 1003 RICE 25 110 2023-11-17 1004 WHEAT 28 65 2023-12-25 1005 PULSES 16 110 2024-01-15 1006 WHEAT 27 55 2024-04-15 1007 WHEAT 25 60 2024-04-30

Database Querying: Asking Questions of a Data Collection

Think of a library. You walk in, and instead of wandering through endless shelves, you go to the librarian and say: "I need all books by R. K. Narayan published after 1980." The librarian knows exactly where to look, finds the relevant books, and hands you a short list. That act of asking — of specifying exactly what you want from a large, organised collection — is the essence of querying.

A database is like that library, but for digital information. It stores data in a structured way, typically in tables with rows and columns. A query is simply a question you ask of that database. You don't need to know where the data lives or how it's stored internally. You just need to state what you want.

The Precise Meaning

In formal terms, a database query is a request for data or information from a database. The request is written in a special language that the database understands. The most common such language is SQL (Structured Query Language), but the concept of querying exists in every database system.

When you query a database, you are doing one of four things:

• Retrieving data (the most common — "show me the customers who live in Delhi")
• Inserting new data ("add this new student record")
• Updating existing data ("change this address")
• Deleting data ("remove this old order")

For a commerce or humanities student, the retrieval part is where the real power lies. You are not just pulling out raw data — you are filtering, sorting, and combining it to get answers.

Why It Matters

A database without querying is like a library with the lights off. The data exists, but you cannot use it. Querying turns stored facts into actionable information.

Consider a small business owner who keeps customer records in a spreadsheet. Without querying, they might scroll through hundreds of rows to find customers who haven't purchased in six months. With a query, they type one request and get the answer instantly. That answer might lead to a targeted marketing campaign, which brings in revenue.

The Intuition Behind It

Every query has a simple structure at its core:

1. What data do you want? (Which columns or fields?)
2. Where is it? (Which table or collection?)
3. Under what conditions? (Which rows match your criteria?)

If you can answer those three questions in plain English, you are already thinking like someone who queries databases. The technical language (SQL) is just a way to write those answers down so the computer understands.

A Real-World Example …