外部キー制約の問題

Question

FKエラーを引き起こす可能性があるのは何ですか？ 'StaffId'フィールド（StaffテーブルのあるFK）を持つデータベースに 'Activity'レコードを挿入しています。問題のstaffId（空白などはありません）を探しましたが、存在しています。他に、外部キーフィールドでエラーが発生する可能性がありますか？

EDIT：エラー：

The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Activities_Staff". The conflict occurred in database "DataWarehouseB", table "dbo.Staff", column 'StaffId'. The statement has been terminated.

Answer 1

SQL Foreign Keyドキュメントは

If the database schema contains foreign key errors that require looking at more than one table definition to identify, then those errors are not detected when the tables are created. Instead, such errors prevent the application from preparing SQL statements that modify the content of the child or parent tables in ways that use the foreign keys. Errors reported when content is changed are "DML errors" and errors reported when the schema is changed are "DDL errors". So, in other words, misconfigured foreign key constraints that require looking at both the child and parent are DML errors. The English language error message for foreign key DML errors is usually "foreign key mismatch" but can also be "no such table" if the parent table does not exist. Foreign key DML errors are may be reported if:

• The parent table does not exist.
• The parent key columns named in the foreign key constraint do not exist.
• The parent key columns named in the foreign key constraint are not the primary key of the parent table and are not subject to a unique constraint using collating sequence specified in the CREATE TABLE.
• The child table references the primary key of the parent without specifying the primary key columns and the number of primary key columns in the parent do not match the number of child key columns.

いくつかのDBにも、その後、non-unique index as a foreign key reference、