Select every nth record in a table or feature class

Summary

To select every nth record in a table, use the Select by Attributes tool with the modulo function (MOD).

• SQL reference for query functions used in ArcGIS: Numeric functions

This avoids the use of Python scripting and can be input to the Feature Class to Feature Class tool. Extra modifications can be made to start at a particular record, as well. 

Procedure

1. In ArcGIS Pro in the Map tab, click Select By Attributes.

2. Turn on the SQL Editor, as shown in the next image.

3. Use the following formula in the Expression box:

MOD(OBJECTID+2n-x, n) = 0

• n is the every nth record
• x is the objectid to start  from

Examples

For every fourth record, starting at OBJECTID = 1:

• n = 4
• x = 1

Therefore: 2n-x = 7, and

MOD(OBJECTID+7,4) = 0

Selects records 1, 5, 9, 13, and so forth.

For every third record, starting at OBJECTID = 2:

• n = 3
• x = 2

MOD(OBJECTID+4,3) = 0

Selects records 2, 5, 8, 11, and so forth.

Note:
This formula fails for 2n < x.