MySQL built-in functions

String functions

Select concat (' Hello ', ' word ', ' my ')  myname; // concat ()    link character functions    output  hellowordmy  myname is the alias Select lcase (' MYSQL ');                     //lcase ()     Convert to lowercase       Output  mysql select length (' string ')                      //length ()     The length of the output string Select ltrim ('   strimg ');                 //ltrim ()    Remove left space Select rtrim (' string   ');                 //rtrim ()    Remove Right space select repeat (' PHP, ', 3);                      //repeat ()   Repeat    output   php,php,php,select replace (' Linux  is very good ', ' Linux ', ' php ')  ;  //replace () Replace     output  php  is very goodselect substr (' Linux is very good ', 1,5);    The starting position of the  //SUBSTR (),mysql  is 1, the output linuxselect space (Ten);                             //space ();   generates 10 spaces

Mathematical functions

Select bin (192);                   //bin ();   decimal turn binary   , Output  11000000select celing (10.1);              //celing ();   rounding up     output  11select floor (10.1);               //floor ();   down rounding    output  10select max (col);                // max ()    Take maximum    aggregate using Select min (COL)                   //min ()    take minimum    aggregation using SELECT SQRT (4);                 //SQRT ()     Open square, Output 2select rand ();   &nbsP;             // rand ()   random    select * from tablename order by rand ()

Date function

Select curdate ();                     //curdate ();   Current date    month Day select curtime ();                      //curtime ();   current time    hours Select now ();                          // Now ();      current date and time    month Day Select unix_timestamp ();                     //unix_ Timestamp ();     returns the current UNIX timestamp select week (' 2015-10-10 ');              //week ();        Returns the week ordinal of the Year select year (' 2016-06-26 ');              //year ();       output  2016 , returns the current year Select datediff (' 2016-10-10 ', ' 2016-10-20 ');        //  output-10, return two dates in a few days

MySQL built-in functions