Select by attribute with field equal to element of vector in ArcPy?

Question

I am trying to select by an attribute with a condition that field equals to an element of a vector. I use a for loop but could not get the right expression for this condition. Here are my codes.

random37 = [30449, 46617, 17309]
pointlayer = "network_nodeSelected"

for random in random37:

randomname = "n" + str(random)
arcpy.MakeFeatureLayer_management(pointlayer,pointlayer)
arcpy.SelectLayerByAttribute_management(pointlayer,'NEW_SELECTION','"ARC_" = random')
arcpy.CopyFeatures_management(pointlayer, randomname)

print randomname

The error message is presented as follows.

Traceback (most recent call last):

File "", line 6, in arcpy.SelectLayerByAttribute_management(pointlayer,'NEW_SELECTION','"ARC_" = point')

File "C:\Program Files (x86)\ArcGIS\Desktop10.6\ArcPy\arcpy\management.py", line 7742, in SelectLayerByAttribute raise e

ExecuteError: ERROR 000358: Invalid expression Failed to execute (SelectLayerByAttribute).

As you can see, my problem is the expression '"ARC_" = random'. But I do not know how to get the right expression.

Answer 1

The problem is the sql expression. Here is the solution.

random37 = [30449,46617,17309]
pointlayer = "network_nodeSelected"
layer1 = "wqi_ConProshp"

for point in random37:
    pointname = "n" + str(point)
    fieldname = 'ARC_'
    whereClause = """{0} = {1}""".format(arcpy.AddFieldDelimiters(pointlayer, fieldname),point)
    arcpy.MakeFeatureLayer_management(pointlayer,pointlayer)    
    arcpy.SelectLayerByAttribute_management(pointlayer,'NEW_SELECTION',whereClause)
    arcpy.CopyFeatures_management(pointlayer, pointname)
    #select the location and then export it

    print pointname

To be honest, I still can not understand how it works but it indeed solves my problem.