Posted over 10 years ago. Visible to the public. Repeats.
MySQL: CONCAT with NULL fields
In MySQL,
CopyCONCAT('foo', 'bar', NULL) = NULL
the NULL always wins in MySQL.
If you would rather treat NULL as an empty string, use CONCAT_WS (concatenation with separator) instead:
CopyCONCAT_WS('', 'foo', 'bar', NULL) = 'foobar'
PostgreSQL
In PostgreSQL the NULL is not viral in CONCAT:
CopyCONCAT('foo', 'bar', NULL) = 'foobar'
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