[GitHub] [calcite] XuQianJin-Stars commented on a change in pull request #1768: [CALCITE-3704] Implement STRCMP function

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XuQianJin-Stars commented on a change in pull request #1768: [CALCITE-3704] Implement STRCMP function
URL: https://github.com/apache/calcite/pull/1768#discussion_r376338376
 
 

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 File path: site/_docs/reference.md
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 @@ -2350,6 +2350,7 @@ semantics.
 | m o p | SOUNDEX(string)                            | Returns the phonetic representation of *string*; throws if *string* is encoded with multi-byte encoding such as UTF-8
 | m | SPACE(integer)                                 | Returns a string of *integer* spaces; returns an empty string if *integer* is less than 1
 | o | SUBSTR(string, position [, substringLength ]) | Returns a portion of *string*, beginning at character *position*, *substringLength* characters long. SUBSTR calculates lengths using characters as defined by the input character set
+| m | STRCMP(string, string)                         | Returns 0 if both of the strings are same and returns -1 when the first argument is smaller than the second according to the defined order and 1 when the second one is smaller the first one.
 
 Review comment:
   > Is the `defined order` customizable ?
   
   I noticed that this function of mysql can change the character set. as follows:
   mysql> SET @s1 = _utf8mb4 'x' COLLATE utf8mb4_0900_ai_ci;
   mysql> SET @s2 = _utf8mb4 'X' COLLATE utf8mb4_0900_ai_ci;
   mysql> SET @s3 = _utf8mb4 'x' COLLATE utf8mb4_0900_as_cs;
   mysql> SET @s4 = _utf8mb4 'X' COLLATE utf8mb4_0900_as_cs;
   mysql> SELECT STRCMP(@s1, @s2), STRCMP(@s3, @s4);
   +------------------+------------------+
   | STRCMP(@s1, @s2) | STRCMP(@s3, @s4) |
   +------------------+------------------+
   |                0 |               -1 |
   +------------------+------------------+

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