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41 lines
1.0 KiB
Plaintext
41 lines
1.0 KiB
Plaintext
SQL Language Extension: LIST
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Function:
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This function returns a string result with the concatenated non-NULL
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values from a group. It returns NULL if there are no non-NULL values.
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Authors:
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Oleg Loa <loa@mail.ru>
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Dmitry Yemanov <dimitr@firebird.org>
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Format:
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<list function> ::=
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LIST '(' [ {ALL | DISTINCT} ] <value expression> [',' <delimiter value> ] ')'
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<delimiter value> ::=
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{ <string literal> | <parameter> | <variable> }
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Syntax Rules:
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1) If neither ALL nor DISTINCT is specified, ALL is implied.
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2) If <delimiter value> is omitted, a comma is used to separate
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the concatenated values.
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Notes:
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1) Numeric and datetime values are implicitly converted to strings
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during evaluation.
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2) The result value is of type BLOB with SUB_TYPE TEXT for all cases
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except list of BLOB with different subtype.
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3) Ordering of values within a group is implementation-defined.
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Examples:
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A)
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SELECT LIST(ID, ':')
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FROM MY_TABLE
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B)
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SELECT TAG_TYPE, LIST(TAG_VALUE)
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FROM TAGS
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GROUP BY TAG_TYPE
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