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SQL SELECT Statement

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The SQL SELECT Statement

The SELECT statement is used to select data from a table. The tabular result is stored in a result table (called the result-set).

Syntax

SELECT column_name(s)
FROM table_name

Note Note: SQL statements are not case sensitive. SELECT is the same as select.


SQL SELECT Example

To select the content of columns named "LastName" and "FirstName", from the database table called "Persons", use a SELECT statement like this:

SELECT LastName,FirstName FROM Persons

The database table "Persons":

LastName FirstName Address City
Hansen Ola Timoteivn 10 Sandnes
Svendson Tove Borgvn 23 Sandnes
Pettersen Kari Storgt 20 Stavanger

The result

LastName FirstName
Hansen Ola
Svendson Tove
Pettersen Kari


Select All Columns

To select all columns from the "Persons" table, use a * symbol instead of column names, like this: 

SELECT * FROM Persons

Result

LastName FirstName Address City
Hansen Ola Timoteivn 10 Sandnes
Svendson Tove Borgvn 23 Sandnes
Pettersen Kari Storgt 20 Stavanger


The Result Set

The result from a SQL query is stored in a result-set. Most database software systems allow navigation of the result set with programming functions, like: Move-To-First-Record, Get-Record-Content, Move-To-Next-Record, etc.

Programming functions like these are not a part of this tutorial. To learn about accessing data with function calls, please visit our ADO tutorial.


Semicolon after SQL Statements?

Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server.

Some SQL tutorials end each SQL statement with a semicolon. Is this necessary? We are using MS Access and SQL Server 2000 and we do not have to put a semicolon after each SQL statement, but some database programs force you to use it.


The SELECT DISTINCT Statement

The DISTINCT keyword is used to return only distinct (different) values.

The SELECT statement returns information from table columns. But what if we only want to select distinct elements?

With SQL, all we need to do is to add a DISTINCT keyword to the SELECT statement:

Syntax

SELECT DISTINCT column_name(s)
FROM table_name


Using the DISTINCT keyword

To select ALL values from the column named "Company" we use a SELECT statement like this:

SELECT Company FROM Orders

"Orders" table

Company OrderNumber
Sega 3412
W3Schools 2312
Trio 4678
W3Schools 6798

Result

Company
Sega
W3Schools
Trio
W3Schools

Note that "W3Schools" is listed twice in the result-set.

To select only DIFFERENT values from the column named "Company" we use a SELECT DISTINCT statement like this:

SELECT DISTINCT Company FROM Orders

Result:

Company
Sega
W3Schools
Trio

Now "W3Schools" is listed only once in the result-set.


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