Firebird 2.1 Language Reference Update

Chapter 11
Aggregate functions
Aggregate functions operate on groups of records, rather than on individual records or variables. They are often
used in combination with a GROUP BY clause.
Available in: DSQL, PSQL
Added in: 2.1
LIST()
Description: LIST returns a string consisting of the non-NULL argument values in the group, separated either
by a comma or by a user-supplied delimiter. If there are no non-NULL values (this includes the case where the
group is empty), NULL is returned.
Result type: BLOB
Syntax:
LIST ([ALL | DISTINCT] expression [, separator])
• ALL (the default) results in all non-NULL values to be listed. With DISTINCT, duplicates are removed,
except if expression is a BLOB.
• The optional separator argument may be a string literal, a parameter or a variable in versions
up to 2.1.3. Starting at 2.1.4 it may be any string expression. This makes it possible to specify e.g.
ascii_char(13) as a separator.
• The expression and separator arguments support BLOBs of any size and character set.
• Date/time and numerical arguments are implicitly converted to strings before concatenation.
• The result is a text BLOB, except when expression is a BLOB of another subtype.
• The ordering of the list values is undefined.
Bug
In versions 2.1–2.1.3, the last part of the result is sometimes truncated. With a single-row set, this happens
when the length gets somewhere above 4000. As the number of rows grows, the threshold climbs rapidly, so
in practice this bug might not raise its head very often. It is fixed in 2.1.4.
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