What is the SQL SELECT Statement

The SELECT statement is used to look for data, or to consult our tables. The syntax for SELECT statement is:

Select * from table_name;

Example 1 Tip: The asterisk (*) is a quick way of selecting all columns!

SQLselect * from test;

ID NAME               EMAIL
------ ------------------ --------------------
1 Mike         [email protected]
2 Dennis         [email protected]
3 Jon         jon2hotmail.com

Or you can restrict the search by calling the rows you chose Example 2

SQLselect id , name from test;

ID NAME
---------- --------------------
1 mike
2 Dennis
3 Jon

• SELECT using condition/s

Sintax: Tip: The (--) is a quick way of commenting a line !

SELECT

FROM table_name WHERE

;

Example:

SQLselect Name --attribute name
from test --table name
where id=1; --condition

NAME
--------------------
mike

Also is important to mention that when the values that will be used in the conditions a string we must place it in single quotes. Integer values do not require single quotes. Example:

SQLselect email from test where name='mike';

EMAIL
--------------------
[email protected]

Conditional selections used in the where clause:

= Equal

It will bring all the names that have the id equal to 1.

SQLSelect name from test where id=1;
NAME
--------------------
mike

Greater than

It will bring all the names that have the id bigger then 1.

SQLSelect name from test where id1;
NAME
--------------------
DennisJon

< Less than

It will bring all the names that have the id smaller then 2.

SQLSelect name from test where id=2;
NAME
--------------------
Mike

= Greater than or equal

SQLSelect name from test where id=2;
NAME
--------------------
Dennis
Jon

<= Less than or equal

SQLSelect name from test where id<=2;
NAME
--------------------
mike
Dennis

< Not equal to

SQLSelect name from test where id<2;
NAME
--------------------
mike
Jon

LIKE

The LIKE pattern matching operator can also be used in the conditional selection of the where clause. Like is a very powerful operator that allows you to select only rows that are "like" what you specify. The percent sign "%" can be used as a wild card to match any possible character that might appear before or after the characters specified.

SQLSelect name from test where name like '%ke';
NAME
--------------------
mike

Notice that the select returned all the names that end up in 'ke' , knowing that '%' sign replaced the rest of the string. We can use the '%' wildcard as well at the end :

• Example:

SQLSelect name from test where name like 'mi%';
NAME
--------------------
Mike

At the beginning and at the end. Example:

SQLselect name from test where name like '%i%';
NAME
-------------------
mike
Dennis

See that the select returned all the names that have letter 'i' inside. Remember that we can use more then one character between the wildcard operators. Example:

SQLSelect name from test where name like '%ik%';
NAME--------------------
Mike

We will learn more about the power of select after we go thrum the basics of Sql first.