arcmap - Using SQL query with ArcPy?

I'm creating a tool that when you type in the city name it will select the city, zoom in and label it. I have the zoom and label working but can't figure out the SQL Query needed to select the city I type in the tool in ArcMap. My code in below.

I'm still new at this

import arcpy as ARCPY

def citySelect():

    mxd = ARCPY.mapping.MapDocument("CURRENT")
    df = ARCPY.mapping.ListDataFrames(mxd)[0]
    city = ARCPY.GetParameter(0)
    cities = ("N:/Lab13/Lab13/cities.lyr")

    ARCPY.SelectLayerByAttribute_management("cities", "NEW_SELECTION",''' "CITY_NAME" = ' city ' ''')
    print city[0]
    layers = arcpy.mapping.ListLayers(mxd, "", df)
    citiesLayer = layers[0]
    df.zoomToSelectedFeatures()
    citiesLayer.showLabels =True
    ARCPY.RefreshActiveView()

citySelect()