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ROWS clause
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Function:
Limits the number of rows retrieved from a select expression. For the
top-level select statement, it would mean a number of rows sent to the host
program.
Author:
Dmitry Yemanov <yemanov@yandex.ru>
Syntax rules:
SELECT ... [ORDER BY <expr_list>] ROWS <expr1> [TO <expr2>]
Scope:
DSQL, PSQL
Example(s):
1. SELECT * FROM T1
UNION ALL
SELECT * FROM T2
ORDER BY COL
ROWS 10 TO 100
2. SELECT COL1, COL2, ( SELECT COL3 FROM T3 ORDER BY COL4 DESC ROWS 1 )
FROM T4
3. DELETE FROM T5
ORDER BY COL5
ROWS 1
Note(s):
1. ROWS is a more understandable alternative to the FIRST/SKIP clauses with
some extra benefits. It can be used in unions and all kind of subqueries.
It is also available in the UPDATE/DELETE statements.
2. When <expr2> is omitted, then ROWS <expr1> is a semantical equivalent for
FIRST <expr1>. When both <expr1> and <expr2> are used, then ROWS <expr1>
TO <expr2> means:
FIRST (<expr2> - <expr1> + 1) SKIP (<expr1> - 1). Note that there's no
semantic equivalent for a SKIP clause used without a FIRST clause.
3. The ROWS-clause is not defined in the SQL standard. For SELECT, consider
the alternative OFFSET and FETCH clauses defined in the SQL standard.
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