An alternative method for exporting MySQL query results to files

Many users can export MySQL query results to files. Generally, "select into outfil" is used to export query results to files, however, the method for exporting the MySQL query results to a file cannot overwrite or add the results to the created file. For example:

 
 

  
  
mysql> select 1 into outfile '/tmp/t1.txt';  
  
  
Query OK, 1 row affected (0.00 sec)  
  
  
mysql> select 1 into outfile '/tmp/t1.txt';  
  
  
ERROR 1086 (HY000): File '/tmp/t1.txt' already exists  
 
 

You can also use another method:

 
 

  
  
mysql> pager cat > /tmp/t1.txt  
  
  
PAGER set to 'cat > /tmp/t1.txt'  
  
  
mysql> select 1;\! cat /tmp/t1.txt  
  
  
1 row in set (0.00 sec)  
  
  
+---+  
  
  
| 1 |  
  
  
+---+  
  
  
| 1 |   
  
  
+---+  
 
 

In this way, you can easily query the differences between two SQL statements:

 
 

  
  
mysql> pager cat > /tmp/t01.txt  
  
  
PAGER set to 'cat > /tmp/t01.txt'  
  
  
mysql> select 12345 union select 67890;  
  
  
2 rows in set (0.02 sec)  
  
  
mysql> pager cat > /tmp/t02.txt  
  
  
PAGER set to 'cat > /tmp/t02.txt'  
  
  
mysql> select 12345 union select 67891;  
  
  
2 rows in set (0.00 sec)  
  
  
mysql> \! vimdiff -o  /tmp/t0[12].txt  
  
  
2 files to edit  
  
  
  +-------+  
  
  
  | 12345 |  
  
  
  +-------+  
  
  
  | 12345 |  
  
  
  | 67890 |                                                                                                                   
  
  
  +-------+                                                                                                                
  
  
/tmp/t01.txt   
  
  
  +-------+  
  
  
  | 12345 |  
  
  
  +-------+  
  
  
  | 12345 |  
  
  
  | 67891 |                                                                                                                   
  
  
  +------+                                                                                                           
  
  
/tmp/t02.txt  
 
 

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