Retrieving Data from a Table (PostgreSQL)

At this point, we have successfully stored data inside the cities table.

Now the next step is to retrieve that data from the database.

To do this, PostgreSQL provides the SELECT statement.

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The Basic SELECT Query

The simplest way to fetch data from a table is:

select * from cities;

When we run this query, PostgreSQL returns all rows from the cities table.

You should see all the cities we inserted earlier:

• Tokyo

• Delhi

• Shanghai

• Sao Paulo

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What Does * Mean?

The * symbol (star) is a shortcut.

It means:

“Select all columns from the table.”

So:

select * from cities;

is the same as saying:

“Give me every column and every row from the cities table.”

This is very useful when:

• exploring a table

• checking inserted data

• learning the structure of a table

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Selecting Specific Columns

Instead of fetching all columns, we can choose only the columns we need.

Example: Name and Country

select name, country from cities;

This query returns:

• only the name column

• and the country column

All other columns are ignored.

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Example: Name and Population

select name, population from cities;

Again, only the specified columns are returned.

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Selecting More Than Two Columns

There is no limit to how many columns you can select.

select name, population, area from cities;

You can list as many columns as you want, as long as they exist in the table.

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Changing Column Order

The order of columns in the result depends on how you write the query, not how the table was created.

For example:

select area, name, population from cities;

PostgreSQL will return:

1. area

2. name

3. population

Even though the table itself was defined in a different order.

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Selecting the Same Column Multiple Times

You can even select the same column more than once:

select name, name, name from cities;

This will return the name column three times.

At first, this might look pointless, but it can be useful later when:

• working with expressions

• creating calculated columns

• formatting output

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Basic SELECT Syntax Recap

The general structure is:

select column1, column2, ...
from table_name;

Or, to get everything:

select * from table_name;

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Summary

• SELECT is used to retrieve data from a table

• * means all columns

• You can select specific columns

• Column order in results is flexible

• Columns can even be repeated

Now that we know how to fetch data, the next step is to filter it.

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What’s Next?

In the next blog, we’ll learn how to:

• filter rows using WHERE

• retrieve only specific records from a table

Just send the next topic whenever you’re ready 👍