MySQL function

Number function

• abs() Absolute value function
• ceil ceiling The smallest integer greater than or equal to the value
• floor The largest integer less than or equal to the value
• least Return the smallest value in the parameter
• greatest Return the maximum value of the list
• radians Angle in radians
• degrees The angle of arc
• sin / asin Sine function / Antisinusoidal function The parameter is radian
• cos / acos cosine / Arccosine
• tan / atan tangent / Anyway
• atan2(m,n) Returns the arctangent of two parameters
• cot Cotangent
• pow / power chengfang
• exp e Of x Power
• sqrt The square root of the parameter
• ln / log e At the bottom of the x The logarithmic
• log10 10 Logarithm of the parameter with the base
• log2 2 Logarithm of the parameter with the base
• rand Random return 0 To 1 Random number between
• rand(x) The parameters are consistent, and the random numbers returned are the same
• round Rounded integer
• round(x,y) y Indicates the number of decimal places reserved
• truncate(x,y) y Indicates that the reserved digits are relative to the decimal digits
• sign Symbolic function , A positive number returns 1, otherwise 0
• div except
• mod Returns the remainder

String function

• ascii Returns the first of the parameters ascii Code value
• char_length Return the number of characters of the parameter
• length Returns the length of the parameter
• concat Return a character with parameters , One of them is NULL, return NULL
• concat_ws Returns the combined character divided by the first parameter , If the first parameter is NULL, Then return to null, Other parameters are null It ignores
• insert(oldstr,x,y,replacestr) character oldstr From the x Location y Characters with a length of characters are replaced by replacestr
• lower / upper Case conversion
• left(str,x) / right(str,x) Returns a specific number of left and right characters
• lpad(str,n,pstr) / rpad(str,n,pstr) The string str Fill left and right until the length reaches n
• ltrim / rtrim / trim Remove the left and right spaces of characters
• trim(substr from str) Remove str Left and right substr
• repeat(str,x) repeat str character x Time
• replace(s,a,b) use b Replace in s Medium a
• strcmp(s1,s2) Compare s1 and s2 Of ascii Code value size of , return -1、0 and 1
• substr(s,x,y) / substring(s,x,y) / mid(s,x,y) Want to be with crop characters s from x The position begins y Characters
• space Return the space character of the parameter space
• locate(substr, str) / position(substr, str) / instr(substr, str) Return string substr stay str The location of
• elt(m,s1,s2…) return m Value corresponds to the position of the following character
• field(s,s1,s2…) Returns that the first parameter appears in the following character list
• find_in_set(s1,s2) return s1 In the character s2 Where in
• reverse return s String with opposite characters
• nullif(s1,s2) If s1 and s2 equal , Then return to null, Otherwise return to s1

Date and time functions

utc It refers to the world coordinated time

• curdate The current date , The format is YYYY-MM-DD
• curtime Current event , The format is HH:MM:SS
• now Current time and date , The format is YYYY-MM-DD HH:MM:SS
• unix_timestamp Convert parameter date to unix Time stamp
• from_unixtime The parameter unix Timestamp to date
• utc_date return utc date
• utc_time return utc Time
• year month Return the year of the date of the parameter 、 month
• monthname Return the English name of the month on which the parameter is located
• day Return the date of the parameter
• dayofweek Returns the number of days in the week corresponding to the number of days in the parameter
• weekday Return the index value of the number of days in the week corresponding to the number of days in the parameter ,0 It corresponds to mid Monday
• week The current date corresponds to the week of the year
• weekofyear The current date corresponds to the week of the year
• dayofyear Corresponding to the number of days in a year
• dayofmonth Corresponding to the number of days in the month
• quarter Current season
• hour minute second The hour corresponding to the parameter 、 Minutes and seconds
• extract(type from date) Return a specific part from the date
• time_to_sec take time Into seconds
• sec_to_time Convert seconds into time
• date_add(date interval expr type) / date_sub(date interval expr type) Date addition and subtraction
• addtime / subtime Add and subtract dates , The second parameter is seconds
• datediff The number of days to calculate the difference between dates
• from_days() from 0000 year 1 month 1 The day after the day parameter
• last_day The last day of the current month
• makedate / maketime Combine time and date
• period_add(time.n) Time plus n after
• to_days() distance 0000 year 1 month 1 Day to parameter day
• date_format(date, format) / time_format(date, format) In the specified format format date
• get_format(date_type, format_type) Return date string format
• str_to_date(str, format) return str according to format Date or time of format conversion

Process handler

• if(v1,v2,v3) If v1 by true, return v2, Otherwise return to v3
• ifnull(v1,v2) If v1 Not for null, return v1, Otherwise return to v2
• case when codition then
• case v1 when v2 then

Encryption and decryption functions

• password encryption
• md5 Yes value Conduct md5 encryption
• encode / decode Use the corresponding values for encryption and decryption

Aggregate functions

• count Count
• max Maximum
• min Minimum
• sum Sum up
• avg Ball average

obtain mysql Information functions

• version Version number
• datebase The database where the current command is located
• user The current user
• last_insert_id The latest value of self increment
• charset(value) mysql Character set
• collation(value) String sorting

Locking and unlocking function

• get_lock(v1,timeout) obtain v1 Lock of , continued timeout
• release_lock Unlock
• is_ferr_lock Judge whether the differential lock can be used
• is_used_lock Determine whether the differential lock is in use

JSON function

• json_contains Inquire about json Whether to include a specific value
• json_search stay json Field specified key In looking for value
• json_pretty Display in an elegant format json
• json_depth Inquire about json The depth of the
• json_length json Length of data
• json_keys return json Data top key Composed of json data
• json_insert stay json Insert data
• json_remove remove json It is specified in key Value
• json_replace to update json It is specified in key Value
• json_set towards json Insert data
• json_type For return json Type of data
• json_valid Judge value Is it effective json data

Window function

• row_number Order
• rank Sort side by side , Through repeated serial numbers
• dense_rank Sort side by side
• percent_rank Grade percentage
• cume_dist Cumulative distribution value
• lag(expr, n) Returns the top of the current line n Yes expr Value
• lead(expr, n) After returning the current line n Yes expr Value
• first_value(expr) /last_value Return to the first or last expr Value
• nth_value(expr,n) Back to page n individual expr Value
• ntile Divide the partitioned ordered data into n A barrel , Record the bucket number

Other functions

• format(value,n) rounding ,n For decimal places

• conv(value, from, to) Binary conversion

• inet_aton take ip Convert to number

• inet_ntoa Convert numbers to ip Address

• benchmark test mysql Time spent processing parameters

• cast take value Turn into type type

• convert take value The character encoding used is converted to char_code