MariaDB and MySQL Common Table Expressions and Window Functions Revealed by Daniel Bartholomew

Author:Daniel Bartholomew
Language: eng
Format: epub
Publisher: Apress, Berkeley, CA

NTILE

The syntax for the NTILE function is:

NTILE (<ntile_expression>) OVER (

[ <partition_definition> ]

[ <order_definition> ]

)

This function returns an integer indicating the group a certain row is in. The number of groups is specified by the <ntile_expression> part, and the numbering starts at 1. Ordered rows in the partition are divided into the specified number of groups, with each group being as equal in size to the other groups as possible.

For example, when using NTILE(2) on the values '1,2,2,3,4' the results would be:

+-------+----------+

| value | ntile(2) |

+-------+----------+

| 1 | 1 |

| 2 | 1 |

| 2 | 1 |

| 3 | 2 |

| 4 | 2 |

+-------+----------+

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