ArcGIS Server question?
You can only do the Change data Source for multiple IF the links are broken. Depending on the situation, one would/could update broken links layer by layer. Update all broken links in Dataframe at once. But what if there are No broken links but want to change the source?
David does not state 'broken layers' anywhere...but rather 'how to change the database conneciton datasource in all layers'
I use py to re-source all layers with the following example:
*caveat: the new datasource must include all the FeatureClasses etc used in the original
Import arcpy
mxd = arcpy.mapping.MapDocument("CURRENT")
mxd.findAndReplaceWorkspacePaths(r"Database Connections\xxxxx.sde",r"Database Connections\xxxx.sde")