Structured Query Language facts for kids

Structured Query Language (SQL) is a special computer language used to talk to and manage databases. Think of a database as a super organized digital filing cabinet where lots of information is stored. SQL helps you find, add, change, or remove information from these cabinets.

When you use SQL, you write commands called SQL queries. These queries are like instructions you give to the database.

SQL is mainly used to:

• INSERT new information into a database.
• DELETE information that is no longer needed from a database.
• UPDATE existing information in a database.
• SELECT (or get) specific information from a database.

What is a Database?

A database is an organized collection of information. Imagine you have a big collection of trading cards. If they are just in a pile, it's hard to find a specific card. But if you organize them in binders by type, then by name, it becomes much easier. A database does this for digital information, making it easy to store, find, and manage.

How SQL Works

SQL works by letting you write simple commands that the database understands. These commands tell the database exactly what you want to do with the data. It's like giving very clear instructions to a robot that manages your information.

Getting Information with SELECT

The `SELECT` command is one of the most common SQL commands. It's used when you want to look at or get information from your database. You tell the database what columns (types of information) you want to see and from which table (a specific collection of data, like a spreadsheet).

For example, if you have a table named 'my_table' and you want to see everything in a column called 'my_column', you would write:

SELECT my_column FROM my_table;

This command tells the database: "Show me the data from 'my_column' that is inside 'my_table'."

Adding New Information with INSERT

The `INSERT INTO` command is used when you want to add new rows of information into a table. Each row is like a new record or entry.

Let's say you have a table called 'people' with columns for 'first_name', 'last_name', 'age', and 'favorite_food'. If you want to add a new person named Bob Page, who is 42 and loves Hamburgers, you would use this command:

INSERT INTO people (first_name, last_name, age, favorite_food) VALUES ("Bob", "Page", "42", "Hamburgers");

This command tells the database: "In the 'people' table, put 'Bob' in the 'first_name' column, 'Page' in 'last_name', '42' in 'age', and 'Hamburgers' in 'favorite_food'." The order of the column names in the first brackets matches the order of the values in the `VALUES` part.

Important Tip for INSERT

Sometimes, people try to insert data without listing the column names, like this:

INSERT INTO people VALUES ("Bob", "Page", "42", "Hamburgers");

While this might work if you are adding data to ALL columns in the exact order they are set up in the table, it's usually safer to list the column names. If you don't, the database might try to put the data into the wrong columns, or it might not work at all if the types of data don't match (like trying to put a word into a column that only stores numbers). Always listing the columns makes your commands clearer and helps prevent mistakes!