Which of the following MySQL fields can be obtained or queried?

Which of the following MySQL fields can be obtained or queried?

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Mysql is often used to query specific fields and occasionally needs to display a part of the value of a specific field. How can this problem be solved?

Then there is a fuzzy query, if you need to match a certain score in the middle, this time like is very embarrassing, there will be some irrelevant records, how to deal with this?

1. Obtain specific digits:
1. Take the last three characters of the url Field

 
 

  
  
select SUBSTRING(url, -3) from link;
 
 

# This method can only be used for a fixed length. For example, the url contains a total of 8 characters, which can be written as follows:

 
 

  
  
select RIGHT(`url`,length(`url`)-5) from link;
 
 

2. 3rd bits from the left (including the third bits)

 
 

  
  
select SUBSTRING(url, 3) from link; 
 
 

3. Take the three digits on the left

 
 

  
  
select SUBSTRING(url, 1, 3) from link;
 
 

# This method can only be used for a fixed length. For example, the url contains a total of 8 characters, which can be written as follows:

 
 

  
  
select LEFT(`url`,length(`url`)-5) from link;
 
 

4. Intercept (take 7 digits from 1st bits, for example, the sDate field value is)

 
 

  
  
select SUBSTRING(sDate, 1,7) from forumdata;
 
 

The query result is 2013-06.

2. query specific digits:
1. Normal Fuzzy search

 
 

  
  
select * from cm_order where ordersn like '%31%';
 
 

2. A field has 13 BITs and the last four or five bits are 31.

 
 

  
  
select * from cm_order where SUBSTRING(ordersn, 9,2) = 31;
  
  
SELECT * from cm_order where RIGHT(`ordersn`,length(`ordersn`)-8) like '31%';
 
 

This type of fuzzy query will produce a lot of irrelevant data, but this type can only be used for fixed-length fuzzy queries, which is much more efficient than normal fuzzy queries.