Oracle series of three filters and sorting

WHERE clause

Using the WHERE clause, the row does not satisfy the conditions to filter out.

Example:

SELECT
    employee_id,
    last_name,
    job_id,
     department_id
FROM   
    employees
WHERE  
    department_id = 90 ;

Character and Date

Character and date to be included in single quotes.
Character case sensitive, sensitive date format.

Example:

SELECT
    last_name,
    job_id,
    department_id
FROM   
    employees
WHERE  
    last_name = 'Whalen';

Comparison operation

Operators	meaning
=	equal
>	more than the
>=	greater or equal to
<	Less than
<=	Less than or equal
<>	It is not equal to (or may be! =)

Use assignment: = sign

comparison operation Example:

SELECT
    last_name,
    salary
FROM  
    employees
WHERE  
    salary <= 3000;

Other comparison operations

Operators	meaning
BETWEEN...AND...	Between two values (inclusive)
IN(set)	Equal to the value of a list
LIKE	Fuzzy query
IS NULL	Null

Use BETWEEN operator to display values within a range of

Example 1:

SELECT
    last_name,
    salary
FROM
    employees
WHERE
    salary BETWEEN 2500 AND 3500;

Values using the IN operator display list

SELECT
    employee_id,
    last_name,
    salary,
    manager_id
FROM
    employees
WHERE
    manager_id IN (
        100,
        101,
        201
    );

LIKE

Similar use the LIKE operator selected value
Selection criteria may include characters or numbers:
% Represents zero or more characters (any characters).
_ Represents one character.

Example:

SELECT
    first_name
FROM
    employees
WHERE
    first_name LIKE 'S%';

'%' And '-' simultaneously

Example:

SELECT
    last_name
FROM
    employees
WHERE
    last_name LIKE '_o%';

ESCAPE

ESCAPE identifier may be used to select '%' and '_' symbol.
Avoidance of special symbols: escaped. For example: A [%] into [\%], [_] into [\ _], then add [ESCAPE '\'] can.

Example:

SELECT
    job_id
FROM
    jobs
WHERE
    job_id LIKE 'IT\_%' ESCAPE '\';

NULL

Use IS (NOT) NULL NULL value is determined.

SELECT
    last_name,
    manager_id
FROM
    employees
WHERE
    manager_id IS NULL;

logic operation

Operators	meaning
AND	And logic
OR	Logical or
NOT	No logic

AND

AND relationship requirements and it is true.

Example:

SELECT
    employee_id,
    last_name,
    job_id,
    salary
FROM
    employees
WHERE
    salary >= 10000
    AND   job_id LIKE '%MAN%';

OR requirements or relation is true.

SELECT
    employee_id,
    last_name,
    job_id,
    salary
FROM
    employees
WHERE
    salary >= 10000
    OR   job_id LIKE '%MAN%';

NOT

NOT this is not within

SELECT
    last_name,
    job_id
FROM
    employees
WHERE
    job_id NOT IN (
        'IT_PROG',
        'ST_CLERK',
        'SA_REP'
    );

priority

priority	name
1	Arithmetic Operators
2	Joiner
3	Comparison operators
4	IS [NOT] NULL, LIKE, [NOT] IN
5	[NOT] BETWEEN
6	NOT
7	AND
8	OR

Parentheses may be used to change the order of priority

ORDER BY clause

ORDER BY clause to sort
ASC (ascend): ascending
DESC (descend): Descending
The end of the ORDER BY clause in the SELECT statement.

Example:

SELECT
    last_name,
    job_id,
    department_id,
    hire_date
FROM
    employees
ORDER BY
    hire_date;

descending sort

SELECT
    last_name,
    job_id,
    department_id,
    hire_date
FROM
    employees
ORDER BY
    hire_date DESC;

Alias Sort by:

SELECT
    employee_id,
    last_name,
    salary * 12 annsal
FROM
    employees
ORDER BY
    annsal;

A plurality of column sorting: Sort the order of ORDER BY list.

SELECT
    last_name,
    department_id,
    salary
FROM
    employees
ORDER BY
    department_id,
    salary DESC;

Oracle series of three filters and sorting

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