migrating-oracle-to-postgres-data-access-code

Replace Oracle.ManagedDataAccess packages with Npgsql, rewrite OracleConnection/OracleCommand types to Npgsql equivalents, fix DbType mappings, and update stored procedure calls. This Skill works through a MigrationChecklist.md item by item and verifies with dotnet build.

Swap Oracle ADO.NET types for Npgsql equivalents: OracleConnection becomes NpgsqlConnection, OracleCommand becomes NpgsqlCommand, and update using directives from Oracle.ManagedDataAccess.Client to Npgsql. Code using IDbConnection abstractions may only need DI registration changes.

Npgsql handles cursors differently than Oracle. For RETURNS TABLE or SETOF functions, use ExecuteReader directly. For RETURNS refcursor, call within a transaction, read the cursor name from the output parameter, then issue FETCH ALL IN with the cursor name.

ROWNUM must become LIMIT, NVL becomes COALESCE, DECODE becomes CASE WHEN, DUAL is removed, CONNECT BY requires recursive CTEs, and MERGE INTO becomes INSERT ON CONFLICT. Also note PostgreSQL does not treat empty strings as NULL like Oracle does.

Yes, replace Oracle.EntityFrameworkCore with Npgsql.EntityFrameworkCore.PostgreSQL and change UseOracle to UseNpgsql in the DbContext configuration. Review OnModelCreating for Oracle-specific column types, but do not run EF migrations if schema is managed externally.