/// <summary>
/// This method generates the SQL to create a new foreign key.
/// This implementation returns
/// ALTER TABLE FullyQualifiedTableName ADD CONSTRAINT escapedConstraintName FOREIGN KEY (escapedForeignKeyColumnNames) REFERENCES FullyQualifiedForeignTableName (escapedForeignColumnNames) ON DELETE CASCADE
/// </summary>
/// <param name="newForeignKey">Info about the foreign key to create.</param>
/// <returns>SQL statements to create the foreign key.</returns>
public virtual IEnumerable <string> CreateForeignKey(ITableSourceForeignKeyInfo newForeignKey)
{
yield return(String.Format("ALTER TABLE {0} ADD CONSTRAINT {1} FOREIGN KEY ({2}) REFERENCES {3} ({4}){5}",
newForeignKey.TableSource.QualifiedName, Identifiers.EscapeIdentifier(newForeignKey.Name),
Identifiers.EscapeIdentifier(newForeignKey.ColumnName), newForeignKey.ReferencedTableSource.QualifiedName,
Identifiers.EscapeIdentifier(newForeignKey.ReferencedColumnName), newForeignKey.IsCascadeDelete? " ON DELETE CASCADE": String.Empty));
}
/// <summary>
/// This method generates the SQL to drop a foreign key previously obtained through the IIntrospectionService API.
/// This implementation returns "ALTER TABLE FullyQualifiedTableName DROP CONSTRAINT escapedConstraintName"
/// </summary>
/// <param name="existingForeignKey">Info about the foreign key to drop.</param>
/// <returns>SQL statements to drop the foreign key.</returns>
public virtual IEnumerable <string> DropForeignKey(ITableSourceForeignKeyInfo existingForeignKey)
{
string statement = String.Format("ALTER TABLE {0} DROP CONSTRAINT {1}", existingForeignKey.TableSource.QualifiedName,
Identifiers.EscapeIdentifier(existingForeignKey.Name));
return(statement.ToEnumerable());
}
public override IEnumerable <string> DropForeignKey(ITableSourceForeignKeyInfo existingForeignKey)
{
string statement = String.Format("ALTER TABLE {0} DROP FOREIGN KEY {1};", Identifiers.EscapeIdentifier(existingForeignKey.TableSource.Name),
Identifiers.EscapeIdentifier(existingForeignKey.Name));
return(statement.ToEnumerable());
}
