Introduction to logical functions of MySQL column Value Comparison

This article mainly introduces the practical application of the logical function IF for MySQL column Value Comparison and the SQL code to be used in actual operations, A few days ago, I found a document on the practical application of the logic function IF for MySQL column Value Comparison on a website with good reputation for sharing.

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Logical function IF SQL code for MySQL column Value Comparison

 
 

  
  
CREATE TABLE `abc` (   
  
  
`uid` int(10) NOT NULL,   
  
  
`num1` int(8) NOT NULL,   
  
  
`num2` int(8) NOT NULL,   
  
  
`num3` int(8) NOT NULL,   
  
  
PRIMARY KEY (`uid`)   
  
  
) ENGINE=InnoDB DEFAULT CHARSET=gbk   
  
  
CREATE TABLE `abc` (  
  
  
`uid` int(10) NOT NULL,  
  
  
`num1` int(8) NOT NULL,  
  
  
`num2` int(8) NOT NULL,  
  
  
`num3` int(8) NOT NULL,  
  
  
PRIMARY KEY (`uid`)  
  
  
) ENGINE=InnoDB DEFAULT CHARSET=gbk   
 
 

Task: Compares the data in each column and displays the uid and maximum data columns.

Method:

SQL code

 
 

  
  
select if((select if(num1>num2,num1,num2))>num3,(select if(num1>num2,num1,num2)),num3)as num,uid from abc;   
  
  
select if((select if(num1>num2,num1,num2))>num3,(select if(num1>num2,num1,num2)),num3)as num,uid from abc;   
 
 

In this way, the writing is not good, and there are no good methods for comparison.

The result is as follows:

Java code
 

 
 

  
  
+-----+-----+   
  
  
| num | uid |   
  
  
+-----+-----+   
  
  
| 3 | 1 |   
  
  
| 3 | 2 |   
  
  
| 4 | 3 |   
  
  
| 5 | 4 |   
  
  
| 8 | 5 |   
  
  
| 13 | 6 |   
  
  
| 56 | 7 |   
  
  
+-----+-----+   
  
  
7 rows in set   
  
  
+-----+-----+  
  
  
| num | uid |  
  
  
+-----+-----+  
  
  
| 3 | 1 |  
  
  
| 3 | 2 |  
  
  
| 4 | 3 |  
  
  
| 5 | 4 |  
  
  
| 8 | 5 |  
  
  
| 13 | 6 |  
  
  
| 56 | 7 |  
  
  
+-----+-----+  
  
  
7 rows in set   
 
 

The above content is an introduction to the logic function IF for MySQL column Value Comparison. I hope you will get something.