MySQL time conversion/string intercept/

String interception:

SELECT SUBSTRING (' ABCDEFG ', 2,5)

To calculate the character length:

Len (String)

--Inquiry 2010 Pre-admission Idselect user from Cf_log where substr (user,0,4) <2010 order by user ASC limit 0, 10;

Number of statistics tuples:

Select COUNT (*) from Cf_user;

Query repeat:

Select count (user), user,pwd,name from Cf_user Group by user have count (user) >1;

the query results are inserted into the table:

INSERT INTO Cf_grade1 select * from Cf_grade where user= "order by term;

Insert into Cf_user (user,pwd,name,degree,dept,major,class,year) SELECT distinct User,pwd,name,degree,dept,major, Class,year from Cf_log;

Insert into Ims_goods_3 (model,name,price) Select Model,name,price from Ims_goods_5 order by model;

Go Weight:

Delete from table where ID not in (the Select Max (ID) from table group by repeating column);

Time Stamp Conversion Week:

DAYOFWEEK () Sunday: 1, Monday: 2 .....

--Query Sunday record SELECT * from D where DAYOFWEEK (From_unixtime (time) = 1;

Get current time:

Select LocalTime (); select now ();--current_timestamp (), same effect

Get YYYY-MM-DD Date

Select Curdate ();--2015-09-06

Dynamic Time:

Sysdate ()

Month Day Conversion:

Set @dt = Now (); Select DayOfWeek (@dt); --1select DayOfMonth (@dt); --6select DayOfYear (@dt); --249 Returns the number of days of the current year

Query the date of the last day of the specified month:

Select Last_day (now ()); -2015-09-30

Two date time difference [return int type]:

If the first parameter is less than the second argument returns a negative number

Select DateDiff (now (), ' 2015-08-28 ');

MySQL time conversion/string intercept/