One NULL Turns the Whole Concatenation Into NULL
With +, one NULL operand makes the whole concatenation NULL and a built-up label vanishes. Use CONCAT, COALESCE, or CONCAT_WS instead.
Technical Articles for the DBA / Developer
With +, one NULL operand makes the whole concatenation NULL and a built-up label vanishes. Use CONCAT, COALESCE, or CONCAT_WS instead.