Sql order by

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Syntax and Parameters of SQL ORDER BY
MySQL ORDER BY examples
SQL References
SQL UNION
SORT operator
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SQL Учебник
SQL Server ORDER BY clause example
Introduction to SQL ORDER BY clause
SQL References
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Practical skills of SQL language
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Поддерживаемые oracle типы соединений в sql: join и другие

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Syntax and Parameters of SQL ORDER BY

How to get current date in sql server

The syntax of the Oracle SQL ORDER BY clause is:

In this clause:

column_name is one of the columns in your SELECT clause or in your table that you want to order by.
column_position is a number that refers to the position of a column in your SELECT statement.
expression is a valid SQL expression that you want to order your results by
ASC or DESC can be used to specify the order of the data. ASC is ascending, and DESC is descending. This is optional, and if it is not provided, the default sort order is ASC.
NULLS FIRST or NULLS LAST can be used to specify how NULL values are sorted. NULLS FIRST means that NULL values are shown at the top of the list, and NULLS LAST means that NULL values are shown at the bottom of the list. The default treatment if this is not specified is NULLS FIRST if the sort is DESC, or NULLS LAST if the sort is ASC or not specified.

Also, the column that you order by does not need to exist in the SELECT clause. So you don’t need to see the column in your results to use it in the ORDER BY.

MySQL ORDER BY examples

Использование таблиц inserted и deleted

We’ll use the table from the sample database for the demonstration.

A) Using MySQL ORDER BY clause to sort the result set by one column example

The following query uses the clause to sort the customers by their last names in ascending order.

Output:

If you want to sort customers by the last name in descending order, you use the after the column in the clause as shown in the following query:

Ouptut:

B) Using MySQL ORDER BY clause to sort the result set by multiple columns example

If you want to sort the customers by the last name in descending order and then by the first name in ascending order, you specify both and in these respective columns as follows:

Output:

In this example, the clause sorts the result set by the last name in descending order first and then sorts the sorted result set by the first name in ascending order to make the final result set.

C) Using MySQL ORDER BY clause to sort a result set by an expression example

See the following table from the sample database.

The following query selects the order line items from the table. It calculates the subtotal for each line item and sorts the result set based on the subtotal.

To make the query more readable, you can assign the expression in the clause a column alias and use that column alias in the clause as shown in the following query:

In this example, we use as the column alias for the expression and sort the result set by the alias.

Since MySQL evaluates the clause before the clause, you can use the column alias specified in the clause in the clause.

SQL References

SQL Keywords
ADD
ADD CONSTRAINT
ALTER
ALTER COLUMN
ALTER TABLE
ALL
AND
ANY
AS
ASC
BACKUP DATABASE
BETWEEN
CASE
CHECK
COLUMN
CONSTRAINT
CREATE
CREATE DATABASE
CREATE INDEX
CREATE OR REPLACE VIEW
CREATE TABLE
CREATE PROCEDURE
CREATE UNIQUE INDEX
CREATE VIEW
DATABASE
DEFAULT
DELETE
DESC
DISTINCT
DROP
DROP COLUMN
DROP CONSTRAINT
DROP DATABASE
DROP DEFAULT
DROP INDEX
DROP TABLE
DROP VIEW
EXEC
EXISTS
FOREIGN KEY
FROM
FULL OUTER JOIN
GROUP BY
HAVING
IN
INDEX
INNER JOIN
INSERT INTO
INSERT INTO SELECT
IS NULL
IS NOT NULL
JOIN
LEFT JOIN
LIKE
LIMIT
NOT
NOT NULL
OR
ORDER BY
OUTER JOIN
PRIMARY KEY
PROCEDURE
RIGHT JOIN
ROWNUM
SELECT
SELECT DISTINCT
SELECT INTO
SELECT TOP
SET
TABLE
TOP
TRUNCATE TABLE
UNION
UNION ALL
UNIQUE
UPDATE
VALUES
VIEW
WHERE

MySQL Functions
String Functions:
ASCII
CHAR_LENGTH
CHARACTER_LENGTH
CONCAT
CONCAT_WS
FIELD
FIND_IN_SET
FORMAT
INSERT
INSTR
LCASE
LEFT
LENGTH
LOCATE
LOWER
LPAD
LTRIM
MID
POSITION
REPEAT
REPLACE
REVERSE
RIGHT
RPAD
RTRIM
SPACE
STRCMP
SUBSTR
SUBSTRING
SUBSTRING_INDEX
TRIM
UCASE
UPPER

Numeric Functions:
ABS
ACOS
ASIN
ATAN
ATAN2
AVG
CEIL
CEILING
COS
COT
COUNT
DEGREES
DIV
EXP
FLOOR
GREATEST
LEAST
LN
LOG
LOG10
LOG2
MAX
MIN
MOD
PI
POW
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SUM
TAN
TRUNCATE

Date Functions:
ADDDATE
ADDTIME
CURDATE
CURRENT_DATE
CURRENT_TIME
CURRENT_TIMESTAMP
CURTIME
DATE
DATEDIFF
DATE_ADD
DATE_FORMAT
DATE_SUB
DAY
DAYNAME
DAYOFMONTH
DAYOFWEEK
DAYOFYEAR
EXTRACT
FROM_DAYS
HOUR
LAST_DAY
LOCALTIME
LOCALTIMESTAMP
MAKEDATE
MAKETIME
MICROSECOND
MINUTE
MONTH
MONTHNAME
NOW
PERIOD_ADD
PERIOD_DIFF
QUARTER
SECOND
SEC_TO_TIME
STR_TO_DATE
SUBDATE
SUBTIME
SYSDATE
TIME
TIME_FORMAT
TIME_TO_SEC
TIMEDIFF
TIMESTAMP
TO_DAYS
WEEK
WEEKDAY
WEEKOFYEAR
YEAR
YEARWEEK

Advanced Functions:
BIN
BINARY
CASE
CAST
COALESCE
CONNECTION_ID
CONV
CONVERT
CURRENT_USER
DATABASE
IF
IFNULL
ISNULL
LAST_INSERT_ID
NULLIF
SESSION_USER
SYSTEM_USER
USER
VERSION

SQL Server Functions
String Functions:
ASCII
CHAR
CHARINDEX
CONCAT
Concat with +
CONCAT_WS
DATALENGTH
DIFFERENCE
FORMAT
LEFT
LEN
LOWER
LTRIM
NCHAR
PATINDEX
QUOTENAME
REPLACE
REPLICATE
REVERSE
RIGHT
RTRIM
SOUNDEX
SPACE
STR
STUFF
SUBSTRING
TRANSLATE
TRIM
UNICODE
UPPER

Numeric Functions:
ABS
ACOS
ASIN
ATAN
ATN2
AVG
CEILING
COUNT
COS
COT
DEGREES
EXP
FLOOR
LOG
LOG10
MAX
MIN
PI
POWER
RADIANS
RAND
ROUND
SIGN
SIN
SQRT
SQUARE
SUM
TAN

Date Functions:
CURRENT_TIMESTAMP
DATEADD
DATEDIFF
DATEFROMPARTS
DATENAME
DATEPART
DAY
GETDATE
GETUTCDATE
ISDATE
MONTH
SYSDATETIME
YEAR

Advanced Functions
CAST
COALESCE
CONVERT
CURRENT_USER
IIF
ISNULL
ISNUMERIC
NULLIF
SESSION_USER
SESSIONPROPERTY
SYSTEM_USER
USER_NAME

MS Access Functions
String Functions:
Asc
Chr
Concat with &
CurDir
Format
InStr
InstrRev
LCase
Left
Len
LTrim
Mid
Replace
Right
RTrim
Space
Split
Str
StrComp
StrConv
StrReverse
Trim
UCase

Numeric Functions:
Abs
Atn
Avg
Cos
Count
Exp
Fix
Format
Int
Max
Min
Randomize
Rnd
Round
Sgn
Sqr
Sum
Val

Date Functions:
Date
DateAdd
DateDiff
DatePart
DateSerial
DateValue
Day
Format
Hour
Minute
Month
MonthName
Now
Second
Time
TimeSerial
TimeValue
Weekday
WeekdayName
Year

Other Functions:
CurrentUser
Environ
IsDate
IsNull
IsNumeric

SQL Quick Ref

SQL UNION

Оператор UNION используется для объединения результирующего набора из двух или более заявлений SELECT.

Каждый оператор SELECT в UNION должен иметь одинаковое количество столбцов
Столбцы также должны иметь схожие типы данных
Столбцы в каждом заявлении SELECT также должны располагаться в том же порядке

Оператор UNION по умолчанию выбирает только отдельные значения. Чтобы разрешить повторяющиеся значения, использовать UNION ALL:

SELECT column_name(s) FROM table1
UNION ALL
SELECT column_name(s) FROM table2;

Примечание: Имена столбцов в результирующем наборе обычно равны именам столбцов в первом заявлении SELECT в UNION.

SORT operator

The task of the sort operator is to put in order the received input data. The following query will retrieve data from the SalesOrderDetail table and the ORDER BY statement provides that the result set will return in ascending order according to the ModifiedDate column.

1
2
3

SELECTCarrierTrackingNumber

FROMSales.SalesOrderDetail

ORDERBYModifiedDateASC

When we check the query plan after the execution of the query, we will see that the storage engine reads the data by way of the clustered index scan operator. As a second step, the sort operator takes 121.317 rows as input and sorts them in ascending order.

Now, let’s take a new example query. This query will use an enlarging copy of the Adventureworks database and it will sort approximately 453.341 rows.

1
2
3
4
5

SELECTCreditCardApprovalCode,AccountNumber

FROMSales.SalesOrderHeaderEnlarged

WHERE

DueDate>’20150601′

ORDERBYDueDateASC

In the compilation phase of the query plan, the query optimizer calculates the memory requirement of the query based
on the estimated number of rows and row sizes, and this memory requirement is called a memory grant or query work
buffer. For some reasons (outdated statistics, wrong cardinality estimation, parameter sniffing, badly defined data
types) the memory grant might be calculated as wrong.

In the execution plan, we see a warning sign on the sort operator which means that the memory grant is not enough
for the sort operation and the query required more memory to perform the sort operation. In this circumstance,
during the execution of the query, the sort operator uses the tempdb database to meet the memory deficit. When we
analyze the sort operator properties, we can find out more detailed information about the tempdb spill issue.

The sort operator uses 45 MB memory but this memory amount is not enough to perform sorting all rows, for this
reason, sort operator used the tempdb database. During the execution of a query, the memory grant can not be changed
dynamically and insufficient memory grant estimations cause this type of issue.

Tip: Row Mode Memory Grant Feedback
feature in SQL Server 2019 helps to overcome this problem without any code changing. The main idea of this feature
is to adjust the memory grant requirement of a query to use the last execution memory grant information. With the
help of this feature, we can assume that several executions of the query the memory grant must be adjusted. The
below image illustrates memory grant changings after the four execution of the query. In the last execution of the
query, the optimizer has decided to find the proper memory grant amount for this query

At the same time, the following options can consider overcoming the tempdb spill issue:

Creating an index that tunes the ORDER BY statement performance
Using the MIN_GRANT_PERCENT query option
Update the outdated statistics

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SQL ОператорыSQL Типы данныхSQL Краткий справочник

SQL Справочник

SQL ОператорыSQL Типы данныхSQL Краткий справочник

SQL Учебник

SQL Server ORDER BY clause example

We will use the table in the sample database from the demonstration.

A) Sort a result set by one column in ascending order

The following statement sorts the customer list by the first name in ascending order:

In this example, because we did not specify or , the clause used by default.

B) Sort a result set by one column in descending order

The following statement sorts the customer list by the first name in descending order.

In this example, because we specified the explicitly, the clause sorted the result set by values in the column in descending order.

C) Sort a result set by multiple columns

The following statement retrieves the first name, last name, and city of the customers. It sorts the customer list by the city first and then by the first name.

D) Sort a result set by multiple columns and different orders

The following statement sorts the customers by the city in descending order and the sort the sorted result set by the first name in ascending order.

E) Sort a result set by a column that is not in the select list

It is possible to sort the result set by a column that does not appear on the select list. For example, the following statement sorts the customer by the state even though the column does not appear on the select list.

Note that the column is defined in the table. If it was not, then you would have an invalid query.

F) Sort a result set by an expression

The function returns the number of characters of a string. The following statement uses the function in the clause to retrieve a customer list sorted by the length of the first name.

G) Sort by ordinal positions of columns

SQL Server allows you to sort the result set based on the ordinal positions of columns that appear in the select list.

The following statement sorts the customers by first name and last name. But instead of specifying the column names explicitly, it uses the ordinal positions of the columns:

In this example, 1 means the column and 2 means the column.

Using the ordinal positions of columns in the clause is considered a bad programming practice for a couple of reasons.

First, the columns in a table don’t have ordinal positions and need to be referenced by name.
Second, when you modify the select list, you may forget to make the corresponding changes in the clause.

Therefore, it is a good practice to always specify the column names explicitly in the clause.

In this tutorial, you have learned how to use the SQL Server clause to sort a result set by columns in ascending or descending order.

Introduction to SQL ORDER BY clause

To sort a result set returned by a SELECT statement, you use the clause. The following query illustrates how to use the clause in a statement:

The clause allows you to sort the result set by a column or an expression with a condition that the value in the column or the returned value of the expression must be sortable i.e., the data type of the result must be the character, numeric or date-time.

To sort a result set in ascending order, you use keyword, and in descending order, you use the keyword. If you don’t specify any keyword explicitly, the clause sorts the result set in ascending order by default.

To sort multiple columns, you just need to specify additional columns in the clause. You can sort by one column in ascending order and another column in descending order.