Correlated Table Updates Supported
Previously, if an UPDATE statement was immediately followed by the FROM keyword, the Enterprise Access gateway blocked queries and issued the error "UPDATE FROM is not supported." This syntax was not allowed in OpenSQL, and none of the gateway DBMSs supported this syntax.
Enterprise Access now supports table and subquery correlation in UPDATE statements with a FROM clause. To allow correlated table updates, which are only supported by Ingres, query translation is performed so that the syntax can be accepted by all host DBMSs. You may now use the correlated update syntax in new applications. This addition should not alter current application behaviors.
The following syntax is now accepted in Enterprise Access OpenSQL:
UPDATE [schema.]table_name
[FROM [schema.]table_name [corr_name]
{ , [schema.]table_name [corr_name]}]
SET column_name = expression {, column_name = expression}
[WHERE search_condition];
For more information about the UPDATE statement, see the Ingres OpenSQL Reference Guide.