#  SUBSTRING_INDEX
__*SUBSTRING_INDEX function*__
+ `SUBSTRING_INDEX(str, delim, count)`: Returns the substring of the string before the delimiter occurrence**count**
  + If the**count** is negative, the direction is reversed
+ For example:
  + `SELECT substring_index('853:888:777:598',':',1), substring_index('853:888:777:598',':',2), substring_index('853:888:777:598',':',-2)\G`  
```10
tidb> SELECT substring_index('853:888:777:598',':',1), 
   -> substring_index('853:888:777:598',':',2), 
   -> substring_index('853:888:777:598',':',-2)\G
*************************** 1. row***************************
 substring_index('853:888:777:598',':',~!@1@!~): 853
 substring_index('853:888:777:598',':',~!@2@!~): 853:888
substring_index('853:888:777:598',':',~!@-2@!~): 777:598
1 row in set (0.00 sec)
```

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- SUBSTRING_INDEX () return the substring from a string before the delimiter for the specified number of occurrences