Copy of the table and ****** ***

Copy Table *** 
    Create Table copy_table SELECT * from Customer; 
    copy of the data structure 
    create table copy_table select * from customer where 0> 1; 
    copy only structural 

similarities: Description index can not be copied can not be copied (increment) 

recording detailed operations: 

the following syntax 
[] represents an optional 
{} indicates mandatory 
by 
    insert [into] table [field name] value | values (field values ....); 
    INTO be omitted 
    [field name] Alternatively 
        , if a write you latter value must match the write field 
        value is not written back to be and the structure of the table exact match 
    value to insert a record 
    values to insert multiple records 

changed 
    update table set field name = new value [, field n = the new value n ] [where condition] 
    may simultaneously edit multiple fields separated by commas Note that the last field can not comma 
    where optionally 
        have to modify the record satisfy the conditions 
        not all modifications to 
delete 
    delete from table [where condition]
    where Optional 
        record delete meet the conditions will 
        not have to delete all 
        if you need to use the truncate table to delete all the table names 
        delete progressive delete efficient than low 
        line number will remain delete delete 

query 
    complete query 
    select [distinct] {* | field name | aggregate function |} from the expression table 
        [where conditions 
        group by field name 
        having conditions 
        order by field names 
        number of displayed limit] 

    Note: the order of the key must be consistent with the above syntax 


    simple query *** *** 

    1. * indicates that all columns are displayed 
    2. the display may be manually specify column may be a plurality 
    3.distinct for removing duplicate records 
        only records taken same 
        column course you can also be displayed manually specify thus come weight 
   4. expression support four arithmetic 


    execution sequence 
     DEF SELECT () 
        from () open file
        where () reads each line and determining whether the condition 
        group () data packets 
        HAVING () and then filtered HAVING after filtering packets for the packet does not occur after only a single 
        DISTINCT () to re- 
        order () for screening after data sorting 
        limit () limit the number of displayed 
        last to display data in accordance with the development of the select field of 

preparing the data: 
Create Table STU (ID int Primary Key AUTO_INCREMENT, name char (10), Math a float, Dictionary Dictionary English a float); 
INSERT into stu values (null, "Zhao", 90,30); insert into stu values (null, " Joe", 90, 60); 
INSERT into stu values (null, "Joe", 90,60); insert into stu values (null, "big Joe", 10,70); 
INSERT into stu values (null, " Li Qingzhao", 100,100); insert into stu values (null, " torrent", 20, 55); 
INSERT INTO stu values (null, "Survival Song", 20, 55);

The total score for all query 

select name, english + math scores from stu;
select name, english + 10 English from stu; 
A prefix field name data fields: 
name: Zhao english: 90 math: 30 
required string concatenation function 
concat (string) 

text columns: 
SELECT 
concat ( "name: ", name), 
the concat (" Dictionary Dictionary English: ", Dictionary Dictionary English), 
  the concat (" Math: ", Math) 
  from STU; 


Things codes ** 
SELECT 
(Case 
    When Dictionary Dictionary English + Math <150 the then 
        the concat (name," shit ") 
    When Math + Dictionary Dictionary English> = 150 the then 
        the concat (name, "Nice") 
End) reviews from stu;