[SQL]-attempted to read or write protected memory. This is often a indication that other memory is corrupt. Solution to the problem

Scene:

OracleDataAdapter execution failed while accessing the database using Oracle.DataAccess.dll.

Abnormal:

System.accessviolationexception was unhandled
hresult=-2147467261
message=attempted to read or write protected memory. This is often a indication that other memory is corrupt.
Source=oracle.dataaccess

Analysis:

The problematic SQL
Select DISTINCT username from user U, role r where U.roleid = r.id and u.id = 1

The correct SQL
SELECT DISTINCT u. Username from user U, role r where U.roleid = r.id and u.id = 1

Summarize:

The specification uses SQL syntax to specify table aliases for federated queries.

[SQL]-attempted to read or write protected memory. This is often a indication that other memory is corrupt. Solution to the problem