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COALESCE
Syntax
COALESCE
• The CHR and CHAR functions are character-set dependent, and support multi-byte
characters. If integer_expression is a valid character encoding integer value in the
current SQL server character set, the function returns the correct character. If it is not a
valid character the function returns a NULL value.
Compatibility
Progress extension
Specifies a series of expressions and returns the first expression whose value is not NULL. If all
the expressions evaluate as null, COALESCE returns a NULL value.
The COALESCE syntax is shorthand notation for a common case that can also be represented in a
CASE expression. The following two formulations are equivalent:
Example This example illustrates the COALESCE function:
Notes • This function is not allowed in a GROUP BY clause.
CONCAT
COALESCE ( expression1, expression2 [... ] )
COALESCE ( expression1 , expression2 , expression3 )
CASE
WHEN expression1 IS NOT NULL THEN expression1
WHEN expression2 IS NOT NULL THEN expression2
ELSE expression3
END
SELECT COALESCE (end_date, start_date) from job_hist;
• Arguments to this function cannot be query expressions.
Compatibility
SQL compatible
Returns a concatenated character string formed by concatenating two arguments.
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