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SELECT /*+ FIRST_ROWS */ field1, field2, field3, ... FROM table1, table2, table3, table4, table5 WHERE table1.id = table2.id AND table2.id = table3.id AND ... table5.userid = 1
20 Μαρ 2018 · FIRST_ROWS(n) is "optimize for the first n rows using all the normal costing algorithms", whereas FIRST_ROWS is "optimizer for the first rows using a pre-defined set of rules that will force index use, nested loops, etc."
Oracle SQL: Select first n rows / rows between n and m (TOP n/LIMIT queries) At times, it's necessary to select the first n rows or the rows between n and m (paging) from a table or query. Here are a few wrong and correct ways to do it.
For example, consider the following PL/SQL block that uses a cursor to retrieve the first 20 hits of a query and uses the FIRST_ROWS hint to optimize the response time:
21 Νοε 2012 · The hints FIRST_ROWS(n) (where n is any positive integer) or FIRST_ROWS instruct Oracle to optimize an individual SQL statement for fast response. FIRST_ROWS(n) affords greater precision, because it instructs Oracle to choose the plan that returns the first n rows most efficiently .
I want to make a SELECT that will return just the first row for each Val, ordering by Kind. Sample output: ID | Val | Kind ----- 2 | 1337 | 1 3 | 3 | 4 How can I build this query?
The aggregate_function argument is any one of the MIN, MAX, SUM, AVG, COUNT, VARIANCE, or STDDEV functions. It operates on values from the rows that rank either FIRST or LAST . If only one row ranks as FIRST or LAST , then the aggregate operates on a singleton (nonaggregate) set.
