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Retrieving Columns of Data with SQL
by Ron Kurtus (revised 17 March 2016)
You can use SQL to retrieve the columns of a database table with the SELECT statement.
You can retrieve all columns, a single column, or several specific columns. It is then up to your programming language to display that data.
Questions you may have include:
- How do you retrieve all columns?
- How do you retrieve a single columns?
- How do you retrieve selected columns?
This lesson will answer those questions.
Retrieve all columns
You can query a database to retrieve all the elements in a database table by using the SELECT statement and wildcard (*) indicator.
SELECT *
FROM table_name;Note: It is standard practice to add ";" at the end of your SQL query. Some databases require it and some don't.
Example
SELECT *
FROM parts_information;
resulting in:
id part part_no cost 1 hood 03-060 500 2 fender 07-340 750 3 bumper 05-021 135
Retrieve single column
The most common query from a database is to collect or retrieve all the elements in a specific column of the database table.
SELECT column_name
FROM table_name;
Example
SELECT part
FROM parts_information;
resulting in:
part hood fender bumper
Retrieve several select columns
You can also retrieve data from several columns by separating the column names with a comma.
SELECT column_1, column_2, column_7
FROM table_name;Note: Do not place a comma after the last item in the list, because it will result in an error message.
Example
SELECT part, cost
FROM parts_information;
yields:
part cost hood 500 fender 750 bumper 135
Summary
The SELECT statement is used to retrieve the columns of a database table. You can retrieve all columns, a single column, or several specific columns.
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Retrieving Columns of Data with SQL