MySQL function library

function library  mysql stored procedure basic functions include: String type, numeric type, date type   A, String class  charset (str)//return string Character set  concat (string2 [,...])//connection string  INSTR (string, substring)//returns the position where substring first appeared in string, does not exist return 0 lcase (string2)//converted to lowercase  left (string2, Length)//From the left side of the string2, take the length character  length (string)//string  load_file (file_name)//read content from File  locate ( substring, string [, Start_position]) with InStr, but can be specified starting position  lpad (string2, length, pad)//repeat pad plus string beginning until string length is Lengt H ltrim (string2)//Remove front-end space  repeat (string2, count)//Repeat Count times  replace (str, SEARCH_STR, REPLACE_STR)//In Use REPLACE_STR in str to replace Search_str rpad (string2, length, pad)//after STR with pad until length is Length rtrim (string2)// Remove the back-end space  strcmp (string1, string2)//character comparison two-string size,  substring (str, position [, length])//starting with the position of STR, Take length characters,  Note: When working with strings in MySQL, the default first character subscript is 1, i.e. the parameter position must be greater than or equal to 1 mysql> select substring (' ABCD ', 0,2);  + ——————— –+ | SUBSTRING (' ABCD ', 0,2) | + ——————— –+ |                      | + ——————— –+ 1 row in Set (0.00 sec )  mysql> Select substring (' ABCD ',  + ——————— –+ | SUBSTRING (' ABCD ', | + ——————— –+ | AB                    | + ——————— –+ 1 row in Set (0.02 sec) &nbs P TRIM ([[[Both| Leading| TRAILING] [padding] from]string2)//Remove the specified character from the specified position  ucase (string2)//Convert to uppercase  right (string2,length)// Take string2 last length character  space (count)//Generate count of spaces   Two, numeric type  abs (number2)//Absolute value  bin (decimal_number)/ /Decimal to Binary  ceiling (number2)//Up rounding  conv (number2,from_base,to_base)//Conversion  floor (NUMBER2)//Down rounding  format (number,decimal_places)//Reserved decimal place  hex (decimalnumber)//Turn hex   NOTE: Hex () to pass in the string, then return its ASC-11 code, such as Hex (' DEF ') returns 4142143  can also pass in a decimal integer, returning its hexadecimal encoding, such as Hex (25) to return 19 least (number, number2 [,..])///To find the minimum  mod ( Numerator, denominator)//redundancy  power (number, POWER )//Index  rand ([seed])// round (number [, decimals])//rounded, decimals to decimal place]  Note: Return types are not all integers, such as:  (1) The default becomes the Shaping value  mysql> select round (1.23);  + ————-+ | Round (1.23) | + ————-+ |           1 | + ————-+ 1 row in Set (0.00 sec)  mysql> Select round (1.56);  + ————-+ | Round (1.56) | + ————-+ |           2 | + ————-+ 1 row in Set (0.00 sec)   (2) can set the number of decimal digits, return float data  mysql> s Elect round (1.567,2);  + —————-+ | Round (1.567,2) | + —————-+ |           1.57 | + —————-+ 1 row in Set (0.00 sec)  sign (number2)//return symbol, plus or minus or 0&nbsp ; SQRT (NUMBER2)//Open square    III, date type  to_days ()   #SELECT to_days (now ())/365   result is 2014.8822  Yearweek ()   #SELECT yearweek (' 2013-07-18 ') result is 201328 addtime (Date2, Time_interval)//Will Time_ Interval to Date2 convert_tz (datetime2, Fromtz, Totz)//convert time zone   Current_date ()//Current date  current_time ()//Current time  current_timestamp ()//Current timestamp  date (datetime)//Return datetime Date part  date_add (date2, INTERVAL d_value d_type)//in Date2 plus date or time  date_format (datetime, Formatcodes)//use for Matcodes format Display datetime date_sub (Date2, INTERVAL d_value d_type)//Minus one time on Date2  datediff (date1, Date2)//Two days Period Difference  day (date)//date  dayname (date)//English week  dayofweek (date)//week (1-7), 1 for Sunday  dayofyear (date)// The day of the Year  extract (Interval_name from date)//The specified part of the date in the Extract  makedate (year, day)//gives the first days of the years and years, the date string is generated   Maketime (hour, minute, second)//Generate time string  monthname (date)//English month name  now ()//Current time  sec_to_time (seconds)// Seconds turn into Time  str_to_date (string, format)//String to time, display  timediff in format format (datetime1, datetime2)//Two time difference  time _to_sec (time)//times to Seconds] week (Date_time [, Start_of_week])//Weeks  year (DateTime)//year  dayofmonth ( DATETIME)//month of day  hour (datetime)//hour last_day (date)//date The last date of the month  microsecond (datetime)//Microsecond  month (DateTime)//month  minute (datetime) Points   Notes: Types available in interval: day, Day_hour, Day_minute, Day_second, HOUR, Hour_minute, Hour_second, MINUTE, Minute_ Second,month, SECOND, Year declare variable_name [, variable_name ...] datatype [DEFAULT value];  which, datatype for MySQL data type, such as: int, FLOAT, DATE, VARCHAR (length)   Example:  declare l_int INT unsigned default 4000000;  DECLARE l_numeric Numeric (8,2) default 9.95; declare l_date date default ' 1999-12-31 ';  declare l_datetime DATETIME default ' 1999-12-31 23:59:59 ';  declare l_varchar varchar (255) Default ' this would not be padded ';