There are two basic types of joins in GIS tables and geo-data: spatial and relational (based on table IDs). Spatial join is the key concept in GIS and that is what sets all GIS technologies apart from other relational databases. Here we start with performing relational joint of list of zipcodes with names to the US zipcode shapefile.

Relational Join

To join table to shapefile based on ID (zipcode) the data type in the column you are planning to join should be the same. Let’s check on data type in Zip code shapefile. Right click on shapefile, select properties and look under Fields tab. The format of the data is Text and size is 5 digits.