database-guide - SKILL.md Agent Skill

name: database-guide description: > MySQL database development guide for the HMIS project. Use when working with database queries, SQL debugging, database schema investigation, MySQL performance tuning, credential management, or database connection troubleshooting. user-invocable: true

MySQL Developer Guide

Security Policy

MySQL credentials MUST NEVER be committed to git
Credentials stored in separate folder outside the project directory
Windows: C:\Credentials\credentials.txt
Linux/Mac: ~/.config/hmis/credentials.txt

Common Database Operations

Structure Investigation

SHOW TABLES LIKE '%bill%';
DESCRIBE bill;
SHOW CREATE TABLE bill;
SELECT COUNT(*) FROM bill WHERE retired = 0;

JPQL Query Patterns

// Standard entity query
String jpql = "SELECT b FROM Bill b WHERE b.retired = false AND b.department = :dept";

// DTO constructor query (use findLightsByJpql)
String jpql = "SELECT new com.divudi.core.data.dto.MyDTO(b.id, b.name) FROM Bill b WHERE ...";
List<MyDTO> results = (List<MyDTO>) facade.findLightsByJpql(jpql, params, TemporalType.TIMESTAMP);

// Aggregate query
String jpql = "SELECT SUM(b.netTotal) FROM Bill b WHERE ...";

Performance Tips

Always include b.retired = false in queries
Use indexed columns in WHERE clauses
Use DTOs instead of full entities for display
Limit result sets with pagination

Local Development Databases

Each developer machine may have different Payara JDBC pool names and JNDI names. Common local databases:

rh — primary dev database (JNDI typically jdbc/rhDS)
ruhunu — useful as a testing environment with richer data coverage

When a restored database has lowercase table names, it must be converted to uppercase before the app can use it. Generate and run the rename script:

SELECT CONCAT('RENAME TABLE `', table_name, '` TO `temp_', table_name, '`; ',
              'RENAME TABLE `temp_', table_name, '` TO `', UPPER(table_name), '`;')
FROM information_schema.tables
WHERE table_schema = '<db_name>' AND table_name != UPPER(table_name);

Then pipe the output into mysql for that database. See src/main/webapp/resources/sql/UpperCase.sql for reference (note: that file targets a specific schema — always generate fresh from the actual database).

Persistence Configuration

Development: Use hardcoded JNDI (machine-specific — check your local Payara setup)
Before push: Must use environment variables (${JDBC_DATASOURCE})

For complete reference, read developer_docs/database/mysql-developer-guide.md.