Mysql所有高阶函数（不常使用，却功能强大）使用记录，不断学习，更新

Mysql高阶函数（不常使用，却功能强大）使用记录

写在前面，所有测试数据库

本文测试数据集，可在此处下载

todo
关于函数的使用要注意的地方，或者有歧义的地方，就是索引和优化的问题

一、Mysql 8.0所有内置函数

函数名	描述
ABS()	Return the absolute value
ACOS()	Return the arc cosine
ADDDATE()	Add time values (intervals) to a date value
ADDTIME()	Add time
AES_DECRYPT()	Decrypt using AES
AES_ENCRYPT()	Encrypt using AES
AND, &&	Logical AND
ANY_VALUE()	Suppress ONLY_FULL_GROUP_BY value rejection
ASCII()	Return numeric value of left-most character
ASIN()	Return the arc sine
=	Assign a value (as part of a SET statement, or as part of the SET clause in an UPDATE statement)
:=	Assign a value
ASYMMETRIC_DECRYPT()	Decrypt ciphertext using private or public key
ASYMMETRIC_DERIVE()	Derive symmetric key from asymmetric keys
ASYMMETRIC_ENCRYPT()	Encrypt cleartext using private or public key
ASYMMETRIC_SIGN()	Generate signature from digest
ASYMMETRIC_VERIFY()	Verify that signature matches digest
ATAN()	Return the arc tangent
ATAN2(), ATAN()	Return the arc tangent of the two arguments
AVG()	Return the average value of the argument
BENCHMARK()	Repeatedly execute an expression
BETWEEN … AND …	Whether a value is within a range of values
BIN()	Return a string containing binary representation of a number
BIN_TO_UUID()	Convert binary UUID to string
BINARY	Cast a string to a binary string
BIT_AND()	Return bitwise AND
BIT_COUNT()	Return the number of bits that are set
BIT_LENGTH()	Return length of argument in bits
BIT_OR()	Return bitwise OR
BIT_XOR()	Return bitwise XOR
&	Bitwise AND
~	Bitwise inversion
	Bitwise OR
^	Bitwise XOR
CAN_ACCESS_COLUMN()	Internal use only
CAN_ACCESS_DATABASE()	Internal use only
CAN_ACCESS_TABLE()	Internal use only
CAN_ACCESS_VIEW()	Internal use only
CASE	Case operator
CAST()	Cast a value as a certain type
CEIL()	Return the smallest integer value not less than the argument
CEILING()	Return the smallest integer value not less than the argument
CHAR()	Return the character for each integer passed
CHAR_LENGTH()	Return number of characters in argument
CHARACTER_LENGTH()	Synonym for CHAR_LENGTH()
CHARSET()	Return the character set of the argument
COALESCE()	Return the first non-NULL argument
COERCIBILITY()	Return the collation coercibility value of the string argument
COLLATION()	Return the collation of the string argument
COMPRESS()	Return result as a binary string
CONCAT()	Return concatenated string
CONCAT_WS()	Return concatenate with separator
CONNECTION_ID()	Return the connection ID (thread ID) for the connection
CONV()	Convert numbers between different number bases
CONVERT()	Cast a value as a certain type
CONVERT_TZ()	Convert from one time zone to another
COS()	Return the cosine
COT()	Return the cotangent
COUNT()	Return a count of the number of rows returned
COUNT(DISTINCT)	Return the count of a number of different values
CRC32()	Compute a cyclic redundancy check value
CREATE_ASYMMETRIC_PRIV_KEY()	Create private key
CREATE_ASYMMETRIC_PUB_KEY()	Create public key
CREATE_DH_PARAMETERS()	Generate shared DH secret
CREATE_DIGEST()	Generate digest from string
CUME_DIST()	Cumulative distribution value
CURDATE()	Return the current date
CURRENT_DATE()	, CURRENT_DATE Synonyms for CURDATE()
CURRENT_ROLE()	Return the current active roles
CURRENT_TIME(), CURRENT_TIME	Synonyms for CURTIME()
CURRENT_TIMESTAMP(), CURRENT_TIMESTAMP	Synonyms for NOW()
CURRENT_USER(), CURRENT_USER	The authenticated user name and host name
CURTIME()	Return the current time
DATABASE()	Return the default (current) database name
DATE()	Extract the date part of a date or datetime expression
DATE_ADD()	Add time values (intervals) to a date value
DATE_FORMAT()	Format date as specified
DATE_SUB()	Subtract a time value (interval) from a date
DATEDIFF()	Subtract two dates
DAY()	Synonym for DAYOFMONTH()
DAYNAME()	Return the name of the weekday
DAYOFMONTH()	Return the day of the month (0-31)
DAYOFWEEK()	Return the weekday index of the argument
DAYOFYEAR()	Return the day of the year (1-366)
DECODE()	Decode a string encrypted using ENCODE()
DEFAULT()	Return the default value for a table column
DEGREES()	Convert radians to degrees
DENSE_RANK()	Rank of current row within its partition, without gaps
DES_DECRYPT()	Decrypt a string
DES_ENCRYPT()	Encrypt a string
DIV	Integer division
	Division operator
ELT()	Return string at index number
ENCODE()	Encode a string
ENCRYPT()	Encrypt a string
=	Equal operator
<=>	NULL-safe equal to operator
EXP()	Raise to the power of
EXPORT_SET()	Return a string such that for every bit set in the value bits, you get an on string and for every unset bit, you get an off string
EXTRACT()	Extract part of a date
ExtractValue()	Extract a value from an XML string using XPath notation
FIELD()	Index (position) of first argument in subsequent arguments
FIND_IN_SET()	Index (position) of first argument within second argument
FIRST_VALUE()	Value of argument from first row of window frame
FLOOR()	Return the largest integer value not greater than the argument
FORMAT()	Return a number formatted to specified number of decimal places
FORMAT_BYTES()	Convert byte count to value with units
FORMAT_PICO_TIME()	Convert time in picoseconds to value with units
FOUND_ROWS()	For a SELECT with a LIMIT clause, the number of rows that would be returned were there no LIMIT clause
FROM_BASE64()	Decode base64 encoded string and return result
FROM_DAYS()	Convert a day number to a date
FROM_UNIXTIME()	Format Unix timestamp as a date
GeomCollection()	Construct geometry collection from geometries
GeometryCollection()	Construct geometry collection from geometries
GET_DD_COLUMN_PRIVILEGES()	Internal use only
GET_DD_CREATE_OPTIONS()	Internal use only
GET_DD_INDEX_SUB_PART_LENGTH()	Internal use only
GET_FORMAT()	Return a date format string
GET_LOCK()	Get a named lock
>	Greater than operator
>=	Greater than or equal operator
GREATEST()	Return the largest argument
GROUP_CONCAT()	Return a concatenated string
GROUPING()	Distinguish super-aggregate ROLLUP rows from regular rows
GTID_SUBSET()	Return true if all GTIDs in subset are also in set; otherwise false.
GTID_SUBTRACT()	Return all GTIDs in set that are not in subset.
HEX()	Hexadecimal representation of decimal or string value
HOUR()	Extract the hour
ICU_VERSION()	ICU library version
IF()	If
IFNULL()	Null if
IN()	Whether a value is within a set of values
INET_ATON()	Return the numeric value of an IP address
INET_NTOA()	Return the IP address from a numeric value
INET6_ATON()	Return the numeric value of an IPv6 address
INET6_NTOA()	Return the IPv6 address from a numeric value
INSERT()	Insert substring at specified position up to specified number of characters
INSTR()	Return the index of the first occurrence of substring
INTERNAL_AUTO_INCREMENT()	Internal use only
INTERNAL_AVG_ROW_LENGTH()	Internal use only
INTERNAL_CHECK_TIME()	Internal use only
INTERNAL_CHECKSUM()	Internal use only
INTERNAL_DATA_FREE()	Internal use only
INTERNAL_DATA_LENGTH()	Internal use only
INTERNAL_DD_CHAR_LENGTH()	Internal use only
INTERNAL_GET_COMMENT_OR_ERROR()	Internal use only
INTERNAL_GET_ENABLED_ROLE_JSON()	Internal use only
INTERNAL_GET_HOSTNAME()	Internal use only
INTERNAL_GET_USERNAME()	Internal use only
INTERNAL_GET_VIEW_WARNING_OR_ERROR()	Internal use only
INTERNAL_INDEX_COLUMN_CARDINALITY()	Internal use only
INTERNAL_INDEX_LENGTH()	Internal use only
INTERNAL_IS_ENABLED_ROLE()	Internal use only
INTERNAL_IS_MANDATORY_ROLE()	Internal use only
INTERNAL_KEYS_DISABLED()	Internal use only
INTERNAL_MAX_DATA_LENGTH()	Internal use only
INTERNAL_TABLE_ROWS()	Internal use only
INTERNAL_UPDATE_TIME()	Internal use only
INTERVAL()	Return the index of the argument that is less than the first argument
IS	Test a value against a boolean
IS_FREE_LOCK()	Whether the named lock is free
IS_IPV4()	Whether argument is an IPv4 address
IS_IPV4_COMPAT()	Whether argument is an IPv4-compatible address
IS_IPV4_MAPPED()	Whether argument is an IPv4-mapped address
IS_IPV6()	Whether argument is an IPv6 address
IS NOT	Test a value against a boolean
IS NOT	NULL NOT NULL value test
IS NULL	NULL value test
IS_USED_LOCK()	Whether the named lock is in use; return connection identifier if true
IS_UUID()	Whether argument is a valid UUID
ISNULL()	Test whether the argument is NULL
JSON_ARRAY()	Create JSON array
JSON_ARRAY_APPEND()	Append data to JSON document
JSON_ARRAY_INSERT()	Insert into JSON array
JSON_ARRAYAGG()	Return result set as a single JSON array
->	Return value from JSON column after evaluating path; equivalent to JSON_EXTRACT().
JSON_CONTAINS()	Whether JSON document contains specific object at path
JSON_CONTAINS_PATH()	Whether JSON document contains any data at path
JSON_DEPTH()	Maximum depth of JSON document
JSON_EXTRACT()	Return data from JSON document
->>	Return value from JSON column after evaluating path and unquoting the result; equivalent to JSON_UNQUOTE(JSON_EXTRACT()).
JSON_INSERT()	Insert data into JSON document
JSON_KEYS()	Array of keys from JSON document
JSON_LENGTH()	Number of elements in JSON document
JSON_MERGE()	(deprecated 8.0.3) Merge JSON documents, preserving duplicate keys. Deprecated synonym for JSON_MERGE_PRESERVE()
JSON_MERGE_PATCH()	Merge JSON documents, replacing values of duplicate keys
JSON_MERGE_PRESERVE()	Merge JSON documents, preserving duplicate keys
JSON_OBJECT()	Create JSON object
JSON_OBJECTAGG()	Return result set as a single JSON object
JSON_OVERLAPS()	Compares two JSON documents, returns TRUE (1) if these have any key-value pairs or array elements in common, otherwise FALSE (0)
JSON_PRETTY()	Print a JSON document in human-readable format
JSON_QUOTE()	Quote JSON document
JSON_REMOVE()	Remove data from JSON document
JSON_REPLACE()	Replace values in JSON document
JSON_SCHEMA_VALID()	Validate JSON document against JSON schema; returns TRUE
JSON_SCHEMA_VALIDATION_REPORT()	Validate JSON document against JSON schema; returns report in JSON format on outcome on validation including success or failure and reasons for failure
JSON_SEARCH()	Path to value within JSON document
JSON_SET()	Insert data into JSON document
JSON_STORAGE_FREE()	Freed space within binary representation of JSON column value following partial update
JSON_STORAGE_SIZE()	Space used for storage of binary representation of a JSON document
JSON_TABLE()	Return data from a JSON expression as a relational table
JSON_TYPE()	Type of JSON value
JSON_UNQUOTE()	Unquote JSON value
JSON_VALID()	Whether JSON value is valid
LAG()	Value of argument from row lagging current row within partition
LAST_DAY	Return the last day of the month for the argument
LAST_INSERT_ID()	Value of the AUTOINCREMENT column for the last INSERT
LAST_VALUE()	Value of argument from last row of window frame
LCASE()	Synonym for LOWER()
LEAD()	Value of argument from row leading current row within partition
LEAST()	Return the smallest argument
LEFT()	Return the leftmost number of characters as specified
<<	Left shift
LENGTH()	Return the length of a string in bytes
<	Less than operator
<=	Less than or equal operator
LIKE	Simple pattern matching
LineString()	Construct LineString from Point values
LN()	Return the natural logarithm of the argument
LOAD_FILE()	Load the named file
LOCALTIME(), LOCALTIME	Synonym for NOW()
LOCALTIMESTAMP, LOCALTIMESTAMP()	Synonym for NOW()
LOCATE()	Return the position of the first occurrence of substring
LOG()	Return the natural logarithm of the first argument
LOG10()	Return the base-10 logarithm of the argument
LOG2()	Return the base-2 logarithm of the argument
LOWER()	Return the argument in lowercase
LPAD()	Return the string argument, left-padded with the specified string
LTRIM()	Remove leading spaces
MAKE_SET()	Return a set of comma-separated strings that have the corresponding bit in bits set
MAKEDATE()	Create a date from the year and day of year
MAKETIME()	Create time from hour, minute, second
MASTER_POS_WAIT()	Block until the slave has read and applied all updates up to the specified position
MATCH	Perform full-text search
MAX()	Return the maximum value
MBRContains()	Whether MBR of one geometry contains MBR of another
MBRCoveredBy()	Whether one MBR is covered by another
MBRCovers()	Whether one MBR covers another
MBRDisjoint()	Whether MBRs of two geometries are disjoint
MBREquals()	Whether MBRs of two geometries are equal
MBRIntersects()	Whether MBRs of two geometries intersect
MBROverlaps()	Whether MBRs of two geometries overlap
MBRTouches()	Whether MBRs of two geometries touch
MBRWithin()	Whether MBR of one geometry is within MBR of another
MD5()	Calculate MD5 checksum
MEMBER OF(	) Returns true (1) if first operand matches any element of JSON array passed as second operand, otherwise returns false (0)
MICROSECOND()	Return the microseconds from argument
MID()	Return a substring starting from the specified position
MIN()	Return the minimum value
-	Minus operator
MINUTE()	Return the minute from the argument
MOD()	Return the remainder
%, MOD	Modulo operator
MONTH()	Return the month from the date passed
MONTHNAME()	Return the name of the month
MultiLineString()	Contruct MultiLineString from LineString values
MultiPoint()	Construct MultiPoint from Point values
MultiPolygon()	Construct MultiPolygon from Polygon values
NAME_CONST()	Cause the column to have the given name
NOT, !	Negates value
NOT BETWEEN … AND …	Whether a value is not within a range of values
!=, <>	Not equal operator
NOT IN()	Whether a value is not within a set of values
NOT LIKE	Negation of simple pattern matching
NOT REGEXP	Negation of REGEXP
NOW()	Return the current date and time
NTH_VALUE()	Value of argument from N-th row of window frame
NTILE()	Bucket number of current row within its partition.
NULLIF()	Return NULL if expr1 = expr2
OCT()	Return a string containing octal representation of a number
OCTET_LENGTH()	Synonym for LENGTH()
OR,
ORD()	Return character code for leftmost character of the argument
PASSWORD()	Calculate and return a password string
PERCENT_RANK()	Percentage rank value
PERIOD_ADD()	Add a period to a year-month
PERIOD_DIFF()	Return the number of months between periods
PI()	Return the value of pi
+	Addition operator
Point()	Construct Point from coordinates
Polygon()	Construct Polygon from LineString arguments
POSITION()	Synonym for LOCATE()
POW()	Return the argument raised to the specified power
POWER()	Return the argument raised to the specified power
PS_CURRENT_THREAD_ID()	Performance Schema thread ID for current thread
PS_THREAD_ID()	Performance Schema thread ID for given thread
QUARTER()	Return the quarter from a date argument
QUOTE()	Escape the argument for use in an SQL statement
RADIANS()	Return argument converted to radians
RAND()	Return a random floating-point value
RANDOM_BYTES()	Return a random byte vector
RANK()	Rank of current row within its partition, with gaps
REGEXP	Whether string matches regular expression
REGEXP_INSTR()	Starting index of substring matching regular expression
REGEXP_LIKE()	Whether string matches regular expression
REGEXP_REPLACE()	Replace substrings matching regular expression
REGEXP_SUBSTR()	Return substring matching regular expression
RELEASE_ALL_LOCKS()	Release all current named locks
RELEASE_LOCK()	Release the named lock
REPEAT()	Repeat a string the specified number of times
REPLACE()	Replace occurrences of a specified string
REVERSE()	Reverse the characters in a string
RIGHT()	Return the specified rightmost number of characters
>>	Right shift
RLIKE	Whether string matches regular expression
ROLES_GRAPHML()	Return a GraphML document representing memory role subgraphs
ROUND()	Round the argument
ROW_COUNT()	The number of rows updated
ROW_NUMBER()	Number of current row within its partition
RPAD()	Append string the specified number of times
RTRIM()	Remove trailing spaces
SCHEMA()	Synonym for DATABASE()
SEC_TO_TIME()	Converts seconds to ‘hh:mm:ss’ format
SECOND()	Return the second (0-59)
SESSION_USER()	Synonym for USER()
SHA1(), SHA()	Calculate an SHA-1 160-bit checksum
SHA2()	Calculate an SHA-2 checksum
SIGN()	Return the sign of the argument
SIN()	Return the sine of the argument
SLEEP()	Sleep for a number of seconds
SOUNDEX()	Return a soundex string
SOUNDS LIKE	Compare sounds
SPACE()	Return a string of the specified number of spaces
SQRT()	Return the square root of the argument
ST_Area()	Return Polygon or MultiPolygon area
ST_AsBinary()	, ST_AsWKB() Convert from internal geometry format to WKB
ST_AsGeoJSON()	Generate GeoJSON object from geometry
ST_AsText(), ST_AsWKT()	Convert from internal geometry format to WKT
ST_Buffer()	Return geometry of points within given distance from geometry
ST_Buffer_Strategy()	Produce strategy option for ST_Buffer()
ST_Centroid()	Return centroid as a point
ST_Contains()	Whether one geometry contains another
ST_ConvexHull()	Return convex hull of geometry
ST_Crosses()	Whether one geometry crosses another
ST_Difference()	Return point set difference of two geometries
ST_Dimension()	Dimension of geometry
ST_Disjoint()	Whether one geometry is disjoint from another
ST_Distance()	The distance of one geometry from another
ST_Distance_Sphere()	Minimum distance on earth between two geometries
ST_EndPoint()	End Point of LineString
ST_Envelope()	Return MBR of geometry
ST_Equals()	Whether one geometry is equal to another
ST_ExteriorRing()	Return exterior ring of Polygon
ST_GeoHash()	Produce a geohash value
ST_GeomCollFromText() , ST_GeometryCollectionFromText(), ST_GeomCollFromTxt()	Return geometry collection from WKT
ST_GeomCollFromWKB(), ST_GeometryCollectionFromWKB()	Return geometry collection from WKB
ST_GeometryN()	Return N-th geometry from geometry collection
ST_GeometryType()	Return name of geometry type
ST_GeomFromGeoJSON()	Generate geometry from GeoJSON object
ST_GeomFromText(), ST_GeometryFromText()	Return geometry from WKT
ST_GeomFromWKB(), ST_GeometryFromWKB()	Return geometry from WKB
ST_InteriorRingN()	Return N-th interior ring of Polygon
ST_Intersection()	Return point set intersection of two geometries
ST_Intersects()	Whether one geometry intersects another
ST_IsClosed()	Whether a geometry is closed and simple
ST_IsEmpty()	Placeholder function
ST_IsSimple()	Whether a geometry is simple
ST_IsValid()	Whether a geometry is valid
ST_LatFromGeoHash()	Return latitude from geohash value
ST_Latitude()	Return latitude of Point
ST_Length()	Return length of LineString
ST_LineFromText(), ST_LineStringFromText()	Construct LineString from WKT
ST_LineFromWKB(), ST_LineStringFromWKB()	Construct LineString from WKB
ST_LongFromGeoHash()	Return longitude from geohash value
ST_Longitude()	Return longitude of Point
ST_MakeEnvelope()	Rectangle around two points
ST_MLineFromText(), ST_MultiLineStringFromText()	Construct MultiLineString from WKT
ST_MLineFromWKB(), ST_MultiLineStringFromWKB()	Construct MultiLineString from WKB
ST_MPointFromText(), ST_MultiPointFromText()	Construct MultiPoint from WKT
ST_MPointFromWKB(), ST_MultiPointFromWKB()	Construct MultiPoint from WKB
ST_MPolyFromText(), ST_MultiPolygonFromText()	Construct MultiPolygon from WKT
ST_MPolyFromWKB(), ST_MultiPolygonFromWKB()	Construct MultiPolygon from WKB
ST_NumGeometries()	Return number of geometries in geometry collection
ST_NumInteriorRing(), ST_NumInteriorRings()	Return number of interior rings in Polygon
ST_NumPoints()	Return number of points in LineString
ST_Overlaps()	Whether one geometry overlaps another
ST_PointFromGeoHash()	Convert geohash value to POINT value
ST_PointFromText()	Construct Point from WKT
ST_PointFromWKB()	Construct Point from WKB
ST_PointN()	Return N-th point from LineString
ST_PolyFromText(), ST_PolygonFromText()	Construct Polygon from WKT
ST_PolyFromWKB(), ST_PolygonFromWKB()	Construct Polygon from WKB
ST_Simplify()	Return simplified geometry
ST_SRID()	Return spatial reference system ID for geometry
ST_StartPoint()	Start Point of LineString
ST_SwapXY()	Return argument with X
ST_SymDifference()	Return point set symmetric difference of two geometries
ST_Touches()	Whether one geometry touches another
ST_Transform()	Transform coordinates of geometry
ST_Union()	Return point set union of two geometries
ST_Validate()	Return validated geometry
ST_Within()	Whether one geometry is within another
ST_X()	Return X coordinate of Point
ST_Y()	Return Y coordinate of Point
STATEMENT_DIGEST()	Compute statement digest hash value
STATEMENT_DIGEST_TEXT()	Compute normalized statement digest
STD()	Return the population standard deviation
STDDEV()	Return the population standard deviation
STDDEV_POP()	Return the population standard deviation
STDDEV_SAMP()	Return the sample standard deviation
STR_TO_DATE()	Convert a string to a date
STRCMP()	Compare two strings
SUBDATE()	Synonym for DATE_SUB() when invoked with three arguments
SUBSTR()	Return the substring as specified
SUBSTRING()	Return the substring as specified
SUBSTRING_INDEX()	Return a substring from a string before the specified number of occurrences of the delimiter
SUBTIME()	Subtract times
SUM()	Return the sum
SYSDATE()	Return the time at which the function executes
SYSTEM_USER()	Synonym for USER()
TAN()	Return the tangent of the argument
TIME()	Extract the time portion of the expression passed
TIME_FORMAT()	Format as time
TIME_TO_SEC()	Return the argument converted to seconds
TIMEDIFF()	Subtract time
*	Multiplication operator
TIMESTAMP()	With a single argument, this function returns the date or datetime expression; with two arguments, the sum of the arguments
TIMESTAMPADD()	Add an interval to a datetime expression
TIMESTAMPDIFF()	Subtract an interval from a datetime expression
TO_BASE64()	Return the argument converted to a base-64 string
TO_DAYS()	Return the date argument converted to days
TO_SECONDS()	Return the date or datetime argument converted to seconds since Year 0
TRIM()	Remove leading and trailing spaces
TRUNCATE()	Truncate to specified number of decimal places
UCASE()	Synonym for UPPER()
-	Change the sign of the argument
UNCOMPRESS()	Uncompress a string compressed
UNCOMPRESSED_LENGTH()	Return the length of a string before compression
UNHEX()	Return a string containing hex representation of a number
UNIX_TIMESTAMP()	Return a Unix timestamp
UpdateXML()	Return replaced XML fragment
UPPER()	Convert to uppercase
USER()	The user name and host name provided by the client
UTC_DATE()	Return the current UTC date
UTC_TIME()	Return the current UTC time
UTC_TIMESTAMP()	Return the current UTC date and time
UUID()	Return a Universal Unique Identifier (UUID)
UUID_SHORT()	Return an integer-valued universal identifier
UUID_TO_BIN()	Convert string UUID to binary
VALIDATE_PASSWORD_STRENGTH()	Determine strength of password
VALUES()	Define the values to be used during an INSERT
VAR_POP()	Return the population standard variance
VAR_SAMP()	Return the sample variance
VARIANCE()	Return the population standard variance
VERSION()	Return a string that indicates the MySQL server version
WAIT_FOR_EXECUTED_GTID_SET()	Wait until the given GTIDs have executed on the slave.
WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS()	(deprecated 8.0.18) Deprecated. Use WAIT_FOR_EXECUTED_GTID_SET().
WEEK()	Return the week number
WEEKDAY()	Return the weekday index
WEEKOFYEAR()	Return the calendar week of the date (1-53)
WEIGHT_STRING()	Return the weight string for a string
XOR	Logical XOR
YEAR()	Return the year
YEARWEEK()	Return the year and week

二、时间类型的函数

2.1、格式化 - DATE_FORMAT

按照年月日统计，分组统计中还有count(1),count(*).count(字段)的区别

SELECT orders.orderDate from orders;

SELECT
	DATE_FORMAT( orders.orderDate, '%Y-%m-%d' ),
	count( orders.orderDate ) 
FROM
	orders 
GROUP BY
	DATE_FORMAT( orders.orderDate, '%Y-%m-%d' );

按照年月统计

SELECT
	DATE_FORMAT( orders.orderDate, '%Y-%m' ),
	count( * ) 
FROM
	orders 
GROUP BY
	DATE_FORMAT( orders.orderDate, '%Y-%m' )

按照年日统计

SELECT
	DATE_FORMAT( orders.orderDate, '%Y-%d' ),
	count( * ) 
FROM
	orders 
GROUP BY
	DATE_FORMAT( orders.orderDate, '%Y-%d' )

2.2、TIMESTAMPDIFF(计算与当前时间差，不同维度)

-- 以月为维度
WITH a AS ( 
SELECT *, TIMESTAMPDIFF( MONTH, orderDate, CURRENT_DATE ( ) ) AS DiffMonth FROM orders 
) SELECT
a.* 
FROM
	a 
WHERE
	a.DiffMonth = 200
-- 以年为维度
WITH a AS ( 
SELECT *, TIMESTAMPDIFF( YEAR, orderDate, CURRENT_DATE ( ) ) AS DiffMonth FROM orders 
) SELECT
a.* 
FROM
	a 
WHERE
	a.DiffMonth <=14 ORDER BY a.DiffMonth
	
-- 以天为维度 
EXPLAIN WITH a AS ( 
SELECT *, TIMESTAMPDIFF( DAY, orderDate, CURRENT_DATE ( ) ) AS DiffMonth FROM orders 
) SELECT
a.* 
FROM
	a 
WHERE
	a.DiffMonth <=1400 ORDER BY a.DiffMonth

或者

EXPLAIN  WITH a AS ( 
SELECT *, DATEDIFF(current_date(),orderDate) AS DiffDay FROM orders 
) SELECT
a.* 
FROM
	a 
WHERE
	a.DiffDay <=1400 ORDER BY a.DiffDay

2.3、 select sys.format_time(‘1’)

select sys.format_time(1)	--1.00ps 
select sys.format_time(1000) --1.00ns
select sys.format_time(1000*1000)	-- 1.00 us
select sys.format_time(1000*1000*1000)	-- 1.00 ms
select sys.format_time(1000*1000*1000*1000)	-- 1.00 s

2.4、

三、字符拼接的函数

3.1、group_concat()

SELECT
	jobTitle '职位',
	GROUP_CONCAT( employees.firstName, ' ', employees.lastName ) '组员',
	COUNT( * ) '数量' 
FROM
	employees 
GROUP BY
	jobTitle;

3.2、concat() 和concat_ws()

-- concat 
SELECT CONCAT(m.lastname,', ',m.firstname) AS 'Manager',
       CONCAT(e.lastname,', ',e.firstname) AS 'Direct report'	
FROM employees e
INNER JOIN employees m ON m.employeeNumber = e.reportsto
ORDER BY manager DESC

-- 这里多了个 IFNULL 函数，结果是把自交笛卡尔积，右表数据空值默认值为 top Manager
SELECT 
    IFNULL(CONCAT(m.lastname, ', ', m.firstname),'Top Manager') AS 'Manager',
    CONCAT(e.lastname, ', ', e.firstname) AS 'Direct report'
FROM
    employees e
        LEFT JOIN
    employees m ON m.employeeNumber = e.reportsto
ORDER BY manager DESC

-- CONCAT_WS
SELECT 
    CONCAT_WS(', ', lastName, firstname) `Full name`
FROM
    employees
ORDER BY `Full name`;

四、结果集拼接构造数据

4.1、union select

单列追加数据

SELECT
    CONCAT(firstName,' ',lastName) fullname
FROM
    employees
UNION SELECT
    CONCAT(contactFirstName,' ',contactLastName)
FROM
    customers;

多列构造初始数据

SELECT
    CONCAT(firstName, ' ', lastName) fullname,
    'Employee' as contactType
FROM
    employees
UNION SELECT
    CONCAT(contactFirstName, ' ', contactLastName),
    'Customer' as contactType
FROM
    customers
ORDER BY
    fullname

五、统计/计算类函数

5.1、row_number使用

常用三个操作

5.1.1、给行分配序号

SELECT
	ROW_NUMBER( ) OVER ( ORDER BY productName ) row_num,
	productName,
	msrp 
FROM
	products 
ORDER BY
	productName;

5.1.2、查找每个组的前N行

WITH inventory AS ( SELECT productLine, productName, quantityInStock, ROW_NUMBER ( ) OVER ( PARTITION BY productLine ORDER BY quantityInStock DESC ) row_num FROM products ) SELECT
productLine,
productName,
quantityInStock 
FROM
	inventory 
WHERE
	row_num <= 3;

SELECT
	productLine,
	productName,
	quantityInStock,
	ROW_NUMBER ( ) OVER ( PARTITION BY productLine ORDER BY quantityInStock DESC ) row_num 
FROM
	products

5.2、RANK(排名函数)

查看所有分区部门，以及所有人的工资排名

SELECT 
        first_name, 
        last_name, 
        department_id,
        salary, 
        RANK() OVER (
            PARTITION BY department_id
            ORDER BY salary) salary_rank
    FROM 
        employees

在此基础上，查询所有部门排名第二的人信息

WITH payroll AS (
    SELECT 
        first_name, 
        last_name, 
        department_id,
        salary, 
        RANK() OVER (
            PARTITION BY department_id
            ORDER BY salary) salary_rank
    FROM 
        employees
)
SELECT 
    first_name, 
    last_name,
    department_name,
    salary
FROM 
    payroll p
    INNER JOIN departments d 
        ON d.department_id = p.department_id
WHERE 
    salary_rank = 2;

每个部门工资最高的人

SELECT 
   department_name,
   first_name,
   last_name,
   salary
FROM 
   (
       SELECT 
           department_name,
           ROW_NUMBER() OVER (
               PARTITION BY department_name
               ORDER BY salary DESC) row_num, 
           first_name, 
           last_name, 
           salary
       FROM 
           employees e
           INNER JOIN departments d 
               ON d.department_id = e.department_id
   ) t
WHERE 
   row_num = 1;

5.3、PARTITION BY

SELECT 
    first_name,
    last_name,
    department_id, 
    ROUND(AVG(salary) OVER (
        PARTITION BY department_id
    )) avg_department_salary
FROM
    employees;

六、其它类函数

6.1、FIELD(),可以自定义排序规则

SELECT
	orderNumber,
STATUS 
FROM
	orders 
ORDER BY
	FIELD( STATUS, 'In Process', 'On Hold', 'Cancelled', 'Resolved', 'Disputed', 'Shipped' );

6.2、FIND_IN_SET(str,strList)

str 要查询的字符串
strList 字段名，参数以“,”分隔，如(1,2,6,8)
查询字段(strList)中包含的结果，返回结果null或记录。

FIND_IN_SET和like的区别？

like是广泛的模糊匹配，字符串中没有分隔符，Find_IN_SET 是精确匹配，字段值以英文","分隔，Find_IN_SET查询的结果要小于like查询的结果。

SELECT FIND_IN_SET("q", null) test;
# null

SELECT FIND_IN_SET("q", "s,q,l");
# 2

SELECT FIND_IN_SET("a", "s,q,l");
# 0

explain select * from nodelist where find_in_set("node1",nodelist.nodecontent);

explain select  count(*) from nodelist;

需要注意的是，在没有索引的情况下，性能很低…

6.3、除重

CREATE TABLE t (
    id INT,
    name VARCHAR(10) NOT NULL
);
 
INSERT INTO t(id,name) 
VALUES(1,'A'),
      (2,'B'),
      (2,'B'),
      (3,'C'),
      (3,'C'),
      (3,'C'),
      (4,'D');	
			

WITH temp AS(SELECT 
    id,
    name,
    ROW_NUMBER() OVER (PARTITION BY id, name ORDER BY id) AS row_num
FROM t) SELECT temp.id,temp.name FROM temp WHERE temp.row_num=1

6.4、COALESCE(返回第一个非空值)

SELECT
	o.city,
	o.postalCode,
	COALESCE ( state, country ) AS Address 
FROM
	offices o