Use Python to determine the SQL syntax for a WHERE clause depending on the workspace type

The first sample looks at the layers in a map document with a hard-coded field value:

Code:
import arcpy

#makes map document object
mxd = arcpy.mapping.MapDocument(r"C:\Data\Maps\Sample.mxd")

#Predetermined FID that is needed.
value = "5"

layername = "states"

layers = arcpy.mapping.ListLayers(mxd, layername)

for layer in layers:
    #finds the workspace path for the layer/Feature Class
    WP = layer.workspacePath
    print WP

    #Creates a describe object for the workspace path
    desWP = arcpy.Describe(WP)

    #Pulls the workspace product type
    WPtype = desWP.workspaceFactoryProgID
    print WPtype

    #Identifies File Geodatabase
    if WPtype == "esriDataSourcesGDB.FileGDBWorkspaceFactory.1":
        #sample where clause for fgdb data
        WhereClause = '"ObjectID" = ' + value
        print WhereClause

    #Identifies Personal Geodatabase
    if WPtype == "esriDataSourcesGDB.AccessWorkspaceFactory.1":
        #sample where clause for mdb data
        WhereClause = "[ObjectID] = " + value
        print WhereClause

    #Identifies SDE database
    if WPtype == "esriDataSourcesGDB.SdeWorkspaceFactory.1":
        #sample where clause for SDE data
        WhereClause = "ObjectID = " + value
        print WhereClause

    #Other (Shapefile, coverage, CAD, VPF, and so on)
    if WPtype == "":
        #sample where clause for shapefile data
        WhereClause = '"ObjectID"= ' + value
        print WhereClause

del WhereClause

The second sample allows for a variable to pass the field name into the WHERE clause.

Code:
import arcpy

#makes map document object
mxd = arcpy.mapping.MapDocument(r"C:\Data\Maps\Sample.mxd")

#field name variable that is needed.
fieldname = "STATE"

#Predetermined value
value = "'NC'"

layername = "states"

layers = arcpy.mapping.ListLayers(mxd, layername)

for layer in layers:
    #finds the workspace path for the layer/Feature Class
    WP = layer.workspacePath
    print WP

    #Creates a describe object for the workspace path
    desWP = arcpy.Describe(WP)

    #Pulls the workspace product type
    WPtype = desWP.workspaceFactoryProgID
    print WPtype

    #Identifies File Geodatabase
    if WPtype == "esriDataSourcesGDB.FileGDBWorkspaceFactory.1":
        #sample where clause for fgdb data
        WhereClause = '"' + fieldname + '"= ' + value
        print WhereClause

    #Identifies Personal Geodatabase
    if WPtype == "esriDataSourcesGDB.AccessWorkspaceFactory.1":
        #sample where clause for mdb data
        WhereClause = "[" + fieldname + "] = " + value
        print WhereClause

    #Identifies SDE database
    if WPtype == "esriDataSourcesGDB.SdeWorkspaceFactory.1":
        #sample where clause for SDE data
        WhereClause = fieldname + "= " + value
        print WhereClause

    #Other (Shapefile, coverage, CAD, VPF, and so on)
    if WPtype == "":
        #sample where clause for shapefile data
        WhereClause = '"' + fieldname + '"= ' + value
        print WhereClause

del WhereClause