A complete guide to MySQL in Ruby — installing the mysql2 gem, connections and connection pools, CRUD with prepared statements, transactions, the Sequel query builder, ActiveRecord with MySQL, schema migrations, indexing strategies, EXPLAIN query optimization, batch processing, and SQL injection prevention security.
A complete guide to Microsoft SQL Server in Ruby — installing tiny_tds and ODBC, connecting with Windows and SQL Server authentication, CRUD with parameterized queries, stored procedures, transactions, pagination with OFFSET FETCH, ActiveRecord with the sqlserver adapter, Sequel, T-SQL vs MySQL syntax differences, and migrating from MySQL to SQL Server.
A complete guide to Oracle Database in Ruby — installing Oracle Instant Client and ruby-oci8, connecting with TNS and Easy Connect, CRUD with bind variables, cursors and fetching, PL/SQL and stored procedures, SEQUENCE for auto-increment, ROWNUM and FETCH FIRST for pagination, transactions, ActiveRecord with the oracle-enhanced adapter, Sequel, Oracle data types, and PL/SQL vs standard SQL syntax differences.
A complete guide to PostgreSQL in Ruby — installing the pg gem, connections and connection pools, CRUD with parameterized queries, ACID transactions, PostgreSQL's unique data types (JSONB, arrays, UUID, hstore), COPY for bulk import, LISTEN/NOTIFY for real-time, ActiveRecord with PostgreSQL, Sequel, schema migrations, GIN and GiST indexing, and EXPLAIN ANALYZE for query optimization.