The database catalog in your database contains one row for each object (constraint, default, log, rule, stored procedure, etc.) created within a database. Because the name of any object must be unique in the database, you cannot assign the same name to two different objects, even if they are different object types (for example, a table and a check constraint).
When you name database objects in a database diagram, you will be alerted if the name you choose is already used by another object. An error will occur in the following situations when you attempt to give an object a name already defined in the database catalog:
| Object you attempt to name |
Object already named in the database catalog | Outcome |
| Table | Table | Error |
| Relationship | Error | |
| Column | Accepted | |
| Constraint | Accepted in the diagram, but causes an error when you attempt to save | |
| Index | Accepted | |
| Relationship | Table | Error |
| Relationship | Error | |
| Column | Accepted | |
| Constraint | Error | |
| Index | Accepted | |
| Column | Table | Accepted |
| Relationship | Error | |
| Column | Error if within same table; accepted across tables | |
| Constraint | Error | |
| Index | Accepted | |
| Constraint | Table | Error |
| Relationship | Error | |
| Column | Accepted | |
| Constraint | Error | |
| Index | Error | |
| Index | Table | Error |
| Relationship | Error | |
| Column | Accepted in the diagram, but causes an error when you attempt to save | |
| Constraint | Error | |
| Index | Error |