Resolve Issues with Object Relational Mapping

This table describes how to address common errors you might encounter while working with ORM methods.

Error Message	Probable Cause	Solution
`Persisted properties must have public access or provide set and get access to database.relational.connection.`	The Database Toolbox™ connection object needs access to the properties mapped to the database in order to read and write them properly.	For any properties without the `ExcludeFromDatabase` attribute, set the access to one of the following: Public `?`database.relational.connection
`Mappable requires at least one property to have the PrimaryKey attribute.`	ORM requires that you specify the primary key as the link between a MATLAB^® object and its corresponding entry in a database table.	Add a property with the `PrimaryKey` attribute. You can add the `AutoIncrement` attribute instead of specifying the `PrimaryKey` value.
`Unknown AutoIncrement syntax for myVendor.`	Database Toolbox does not have information on how to create the autoincrementing keys for this vendor.	Use the `execute` function to create the table with an SQL query.
`AutoIncrement properties cannot be written to the database with specified values. Set the property to an empty or missing value to allow the database to set the value automatically.`	The `ormwrite` method does not support inserting known values to an autoincrementing primary key column. Inserting known values differs from vendor to vendor.	Set the value of the `AutoIncrement` property to an empty value to insert a new row into the database table.
`Properties with the AutoIncrement attribute must also have the PrimaryKey attribute.`	Database Toolbox supports the `AutoIncrement` attribute for properties that also have the `PrimaryKey` attribute.	If you want the property with the `AutoIncrement` attribute to also be a primary key, add the `PrimaryKey` attribute to it. If the property is not a primary key, remove the `AutoIncrement` attribute and set the value of the property manually.
`AutoIncrement properties must have integer types.`	A property with the `AutoIncrement` attribute was assigned a non-integer class validation.	Specify the class validation of the property as an integer type.
`Unknown syntax to return inserted keys for Oracle.`	Oracle^® does not specify a syntax for retrieving the primary keys after rows have been inserted.	Do not specify an output to `ormwrite` when using autoincrementing values with Oracle ODBC. To access the values of inserted keys, use `ormread` with an appropriate `RowFilter` value to return your object to MATLAB.