Troubleshoot tables and columns (ADP)

The formula in the calculated column contains an error. Common formula errors include:

• Mismatched parentheses.
• Misspelled column names.
• Using an operator on a column whose data type does not support that operator.

An identity column contains system-generated, sequential values that uniquely identify each row within a table. Keep in mind the following guidelines when creating an identity column:

• An identity column must have a datatype of bigint, int, smallint, tinyint, decimal, or numeric with a scale of 0.
• An identity column cannot have Null values. All identity columns must contain unique values other than Null. To make the column an identity column, first clear the Allow Nulls check box on the Column Property dialog box.
• An identity column cannot have default values.
• The identity increment or seed must be a number that can be stored in the data type size you have chosen. If the data type of the column is tinyint, you must enter a positive number. For any other data type, you can enter a positive or negative number.

• A table must have at least one column that is not a computed column. You can, however, create a view containing all computed columns.
• You can only have one copy of any table on a diagram. If you want to create a new table that has some of the same columns as an existing table, you can duplicate an existing table as the first step in creating a new table.
• The table being loaded into memory has a user-defined data type that is not recognized. The table you are loading into memory refers to a recently created user-defined data type, but your in-memory list of user-defined data types does not include it. Because the data type was created recently, it is not present in local memory. All user-defined data types are loaded from the database into local memory when you open the first Table Designer window or database diagram within your connection to that database. To refresh your in-memory copy of the database's user-defined data types, close all open database diagrams and Table Designer windows within that database connection. After you close them all, reopen them in turn. When you reopen the first one, the list of user-defined data types will be refreshed.
• The contents of the database and the in-memory contents of the Table Designer may be in conflict. This conflict may occur because another user has recently modified the table you are working on, but the Table Designer retains the older version of the table in your local memory. The Table Designer needs to load information about the other table to which you are trying to create a relationship. For example, it needs to load the details about the other table's columns, so you can choose which columns from the table you are designing correspond to columns in the other table. Before proceeding to load the other table into your local memory, the Table Designer will reconcile these conflicts accordingly. The Table Designer does not reconcile all differences between your local memory and the database. It reconciles only those differences that would otherwise prevent you from creating the relationship you are trying to create.

Microsoft Access stores either a zero (0) or a minus one (-1) in the Access database Yes/No data type. An Access database interprets 0 as a 0, No, or False value, and interprets anything else as a –1, Yes, or True value.

By contrast, SQL Server stores either a zero (0) or a plus one (+1) in the bit data type. An Access project interprets 0 as a False value, and interprets plus one (+1) as a True value.