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* translate [select] section into Chinese to improve readability * trigger ci Co-authored-by: mikepop7 <> Co-authored-by: Ivan Blinkov <github@blinkov.ru>
1.4 KiB
1.4 KiB
| toc_title |
|---|
| LIMIT |
LIMIT
LIMIT m 允许选择结果中起始的 m 行。
LIMIT n, m 允许选择个 m 从跳过第一个结果后的行 n 行。 与 LIMIT m OFFSET n 语法是等效的。
n 和 m 必须是非负整数。
如果没有 ORDER BY 子句显式排序结果，结果的行选择可能是任意的和非确定性的。
LIMIT … WITH TIES 修饰符
如果为 LIMIT n[,m] 设置了 WITH TIES ，并且声明了 ORDER BY expr_list, you will get in result first n or n,m rows and all rows with same ORDER BY fields values equal to row at position n for LIMIT n and m for LIMIT n,m.
此修饰符可以与： ORDER BY … WITH FILL modifier 组合使用.
例如以下查询：
SELECT * FROM (
SELECT number%50 AS n FROM numbers(100)
) ORDER BY n LIMIT 0,5
返回
┌─n─┐
│ 0 │
│ 0 │
│ 1 │
│ 1 │
│ 2 │
└───┘
单子执行了 WITH TIES 修饰符后
SELECT * FROM (
SELECT number%50 AS n FROM numbers(100)
) ORDER BY n LIMIT 0,5 WITH TIES
则返回了以下的数据行
┌─n─┐
│ 0 │
│ 0 │
│ 1 │
│ 1 │
│ 2 │
│ 2 │
└───┘
cause row number 6 have same value “2” for field n as row number 5