docs/en/sql-reference/sql-functions/string-functions/concat_ws.md
This function uses the first argument sep as the separator which combines the second with the rest to form a string. If the separator is NULL, the result is NULL. concat_ws does not skip empty strings, but it will skip NULL values.
VARCHAR concat_ws(VARCHAR sep, VARCHAR str,...)
MySQL > select concat_ws("Rock", "Star", "s");
+--------------------------------+
| concat_ws('Rock', 'Star', 's') |
+--------------------------------+
| StarRocks |
+--------------------------------+
MySQL > select concat_ws(NULL, "Star", "s");
+------------------------------+
| concat_ws(NULL, 'Star', 's') |
+------------------------------+
| NULL |
+------------------------------+
1 row in set (0.01 sec)
MySQL > StarRocks > select concat_ws("Rock", "Star", NULL, "s");
+--------------------------------------+
| concat_ws('Rock', 'Star', NULL, 's') |
+--------------------------------------+
| StarRocks |
+--------------------------------------+
1 row in set (0.04 sec)
CONCAT_WS,CONCAT,WS