Friday, 5 October 2012

Learn simple SQL SELECT Statement

The SELECT statement is used to select data from a database.

The result is stored in a result table, called the result-set.

SQL SELECT Syntax

SELECT column_name(s)

FROM table_name

and

SELECT * FROM table_name

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

________________________________________

An SQL SELECT Example

The "Persons" table:
P_Id    LastName    FirstName    Address    City
Hansen    Ola    Timoteivn 10 Sandnes
2    Svendson    Tove    Borgvn 23 Sandnes
3    Pettersen    Kari    Storgt 20  Stavanger


Now we want to select the content of the columns named "LastName" and "FirstName" from the table above.

We use the following SELECT statement:

SELECT LastName,FirstName FROM Persons

The result-set will look like this:
LastName    FirstName   
Hansen    Ola   
Svendson    Tove   
Pettersen    Kari   


________________________________________

SELECT * Example

Now we want to select all the columns from the "Persons" table.

We use the following SELECT statement:

SELECT * FROM Persons

Tip: The asterisk (*) is a quick way of selecting all columns!

The result-set will look like this:
P_Id    LastName    FirstName    Address    City
Hansen    Ola    Timoteivn 10 Sandnes
2    Svendson    Tove    Borgvn 23 Sandnes
3    Pettersen    Kari    Storgt 20  Stavanger


The SQL SELECT Statement

The SELECT statement is used to select data from a database.

The result is stored in a result table, called the result-set.

SQL SELECT Syntax

SELECT column_name(s)

FROM table_name

and

SELECT * FROM table_name

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

________________________________________

An SQL SELECT Example

The "Persons" table:
P_Id    LastName    FirstName    Address    City
Hansen    Ola    Timoteivn 10 Sandnes
2    Svendson    Tove    Borgvn 23 Sandnes
3    Pettersen    Kari    Storgt 20  Stavanger


Now we want to select the content of the columns named "LastName" and "FirstName" from the table above.

We use the following SELECT statement:

SELECT LastName,FirstName FROM Persons

The result-set will look like this:

LastName    FirstName   
Hansen    Ola   
Svendson    Tove   
Pettersen    Kari   

________________________________________

SELECT * Example

Now we want to select all the columns from the "Persons" table.

We use the following SELECT statement:

SELECT * FROM Persons

Tip: The asterisk (*) is a quick way of selecting all columns!

The result-set will look like this:

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

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