Skill: gitgoodordietrying/sql-toolkit (version 1.0.0)

--- name: sql-toolkit description: Query, design, migrate, and optimize SQL databases. Use when working with SQLite, PostgreSQL, or MySQL — schema design, writing queries, creating migrations, indexing, backup/restore, and debugging slow queries. No ORMs required. metadata: {"clawdbot":{"emoji":"🗄️","requires":{"anyBins":["sqlite3","psql","mysql"]},"os":["linux","darwin","win32"]}} --- # SQL Toolkit Work with relational databases directly from the command line. Covers SQLite, PostgreSQL, and MySQL with patterns for schema design, querying, migrations, indexing, and operations. ## When to Use - Creating or modifying database schemas - Writing complex queries (joins, aggregations, window functions, CTEs) - Building migration scripts - Optimizing slow queries with indexes and EXPLAIN - Backing up and restoring databases - Quick data exploration with SQLite (zero setup) ## SQLite (Zero Setup) SQLite is included with Python and available on every system. Use it for local data, prototyping, and single-file databases. ### Quick Start ```bash # Create/open a database sqlite3 mydb.sqlite # Import CSV directly sqlite3 mydb.sqlite ".mode csv" ".import data.csv mytable" "SELECT COUNT(*) FROM mytable;" # One-liner queries sqlite3 mydb.sqlite "SELECT * FROM users WHERE created_at > '2026-01-01' LIMIT 10;" # Export to CSV sqlite3 -header -csv mydb.sqlite "SELECT * FROM orders;" > orders.csv # Interactive mode with headers and columns sqlite3 -header -column mydb.sqlite ``` ### Schema Operations ```sql -- Create table CREATE TABLE users ( id INTEGER PRIMARY KEY AUTOINCREMENT, email TEXT NOT NULL UNIQUE, name TEXT NOT NULL, created_at TEXT DEFAULT (datetime('now')), updated_at TEXT DEFAULT (datetime('now')) ); -- Create with foreign key CREATE TABLE orders ( id INTEGER PRIMARY KEY AUTOINCREMENT, user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE, total REAL NOT NULL CHECK(total >= 0), status TEXT NOT NULL DEFAULT 'pending' CHECK(status IN ('pending','paid','shipped','cancelled')), created_at TEXT DEFAULT (datetime('now')) ); -- Add column ALTER TABLE users ADD COLUMN phone TEXT; -- Create index CREATE INDEX idx_orders_user_id ON orders(user_id); CREATE UNIQUE INDEX idx_users_email ON users(email); -- View schema .schema users .tables ``` ## PostgreSQL ### Connection ```bash # Connect psql -h localhost -U myuser -d mydb # Connection string psql "postgresql://user:pass@localhost:5432/mydb?sslmode=require" # Run single query psql -h localhost -U myuser -d mydb -c "SELECT NOW();" # Run SQL file psql -h localhost -U myuser -d mydb -f migration.sql # List databases psql -l ``` ### Schema Design Patterns ```sql -- Use UUIDs for distributed-friendly primary keys CREATE EXTENSION IF NOT EXISTS "uuid-ossp"; CREATE TABLE users ( id UUID PRIMARY KEY DEFAULT uuid_generate_v4(), email TEXT NOT NULL, name TEXT NOT NULL, password_hash TEXT NOT NULL, role TEXT NOT NULL DEFAULT 'user' CHECK(role IN ('user','admin','moderator')), created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(), updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(), CONSTRAINT users_email_unique UNIQUE(email) ); -- Auto-update updated_at CREATE OR REPLACE FUNCTION update_modified_column() RETURNS TRIGGER AS $$ BEGIN NEW.updated_at = NOW(); RETURN NEW; END; $$ LANGUAGE plpgsql; CREATE TRIGGER update_users_modtime BEFORE UPDATE ON users FOR EACH ROW EXECUTE FUNCTION update_modified_column(); -- Enum type (PostgreSQL-specific) CREATE TYPE order_status AS ENUM ('pending', 'paid', 'shipped', 'delivered', 'cancelled'); CREATE TABLE orders ( id UUID PRIMARY KEY DEFAULT uuid_generate_v4(), user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE, status order_status NOT NULL DEFAULT 'pending', total NUMERIC(10,2) NOT NULL CHECK(total >= 0), metadata JSONB DEFAULT '{}', created_at TIMESTAMPTZ NOT NULL DEFAULT NOW() ); -- Partial index (only index active orders — smaller, faster) CREATE INDEX idx_orders_active ON orders(user_id, created_at) WHERE status NOT IN ('delivered', 'cancelled'); -- GIN index for JSONB queries CREATE INDEX idx_orders_metadata ON orders USING GIN(metadata); ``` ### JSONB Queries (PostgreSQL) ```sql -- Store JSON INSERT INTO orders (user_id, total, metadata) VALUES ('...', 99.99, '{"source": "web", "coupon": "SAVE10", "items": [{"sku": "A1", "qty": 2}]}'); -- Query JSON fields SELECT * FROM orders WHERE metadata->>'source' = 'web'; SELECT * FROM orders WHERE metadata->'items' @> '[{"sku": "A1"}]'; SELECT metadata->>'coupon' AS coupon, COUNT(*) FROM orders GROUP BY 1; -- Update JSON field UPDATE orders SET metadata = jsonb_set(metadata, '{source}', '"mobile"') WHERE id = '...'; ``` ## MySQL ### Connection ```bash mysql -h localhost -u root -p mydb mysql -h localhost -u root -p -e "SELECT NOW();" mydb ``` ### Key Differences from PostgreSQL ```sql -- Auto-increment (not SERIAL) CREATE TABLE users ( id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY, email VARCHAR(255) NOT NULL UNIQUE, name VARCHAR(255) NOT NULL, created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP, updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; -- JSON type (MySQL 5.7+) CREATE TABLE orders ( id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY, user_id BIGINT UNSIGNED NOT NULL, metadata JSON, FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE ); -- Query JSON SELECT * FROM orders WHERE JSON_EXTRACT(metadata, '$.source') = 'web'; -- Or shorthand: SELECT * FROM orders WHERE metadata->>'$.source' = 'web'; ``` ## Query Patterns ### Joins ```sql -- Inner join (only matching rows) SELECT u.name, o.total, o.status FROM users u INNER JOIN orders o ON o.user_id = u.id WHERE o.created_at > '2026-01-01'; -- Left join (all users, even without orders) SELECT u.name, COUNT(o.id) AS order_count, COALESCE(SUM(o.total), 0) AS total_spent FROM users u LEFT JOIN orders o ON o.user_id = u.id GROUP BY u.id, u.name; -- Self-join (find users with same email domain) SELECT a.name, b.name, SPLIT_PART(a.email, '@', 2) AS domain FROM users a JOIN users b ON SPLIT_PART(a.email, '@', 2) = SPLIT_PART(b.email, '@', 2) WHERE a.id < b.id; ``` ### Aggregations ```sql -- Group by with having SELECT status, COUNT(*) AS cnt, SUM(total) AS revenue FROM orders GROUP BY status HAVING COUNT(*) > 10 ORDER BY revenue DESC; -- Running total (window function) SELECT date, revenue, SUM(revenue) OVER (ORDER BY date) AS cumulative_revenue FROM daily_sales; -- Rank within groups SELECT user_id, total, RANK() OVER (PARTITION BY user_id ORDER BY total DESC) AS rank FROM orders; -- Moving average (last 7 entries) SELECT date, revenue, AVG(revenue) OVER (ORDER BY date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS ma_7 FROM daily_sales; ``` ### Common Table Expressions (CTEs) ```sql -- Readable multi-step queries WITH monthly_revenue AS ( SELECT DATE_TRUNC('month', created_at) AS month, SUM(total) AS revenue FROM orders WHERE status = 'paid' GROUP BY 1 ), growth AS ( SELECT month, revenue, LAG(revenue) OVER (ORDER BY month) AS prev_revenue, ROUND((revenue - LAG(revenue) OVER (ORDER BY month)) / NULLIF(LAG(revenue) OVER (ORDER BY month), 0) * 100, 1) AS growth_pct FROM monthly_revenue ) SELECT * FROM growth ORDER BY month; -- Recursive CTE (org chart / tree traversal) WITH RECURSIVE org_tree AS ( SELECT id, name, manager_id, 0 AS depth FROM employees WHERE manager_id IS NULL UNION ALL SELECT e.id, e.name, e.manager_id, t.depth + 1 FROM employees e JOIN org_tree t ON e.manager_id = t.id ) SELECT REPEAT(' ', depth) || name AS org_chart FROM org_tree ORDER BY depth, name; ``` ## Migrations ### Manual Migration Script Pattern ```bash #!/bin/bash # migrate.sh - Run numbered SQL migration files DB_URL="${1:?Usage: migrate.sh <db-url>}" MIGRATIONS_DIR="./migrations" # Create tracking table psql "$DB_URL" -c "CREATE TABLE IF NOT EXISTS schema_migrations ( version TEXT PRIMARY KEY, applied_at TIMESTAMPTZ DEFAULT NOW() );" # Run pending migrations in order for file in $(ls "$MIGRATIONS_DIR"/*.sql | sort); do version=$(basename "$file" .sql) already=$(psql "$DB_URL" -tAc "SELECT 1 FROM schema_migrations WHERE version='$version';") if [ "$already" = "1" ]; then echo "SKIP: $version (already applied)" continue fi echo "APPLY: $version" psql "$DB_URL" -f "$file" && \ psql "$DB_URL" -c "INSERT INTO schema_migrations (version) VALUES ('$version');" || { echo "FAILED: $version" exit 1 } done echo "All migrations applied." ``` ### Migration File Convention ``` migrations/ 001_create_users.sql 002_create_orders.sql 003_add_users_phone.sql 004_add_orders_metadata_index.sql ``` Each file: ```sql -- 003_add_users_phone.sql -- Up ALTER TABLE users ADD COLUMN phone TEXT; -- To reverse: ALTER TABLE users DROP COLUMN phone; ``` ## Query Optimization ### EXPLAIN (PostgreSQL) ```sql -- Show query plan EXPLAIN SELECT * FROM orders WHERE user_id = '...' AND status = 'paid'; -- Show actual execution times EXPLAIN (ANALYZE, BUFFERS, FORMAT TEXT) SELECT * FROM orders WHERE user_id = '...' AND status = 'paid'; ``` **What to look for:** - `Seq Scan` on large tables → needs an index - `Nested Loop` with large row counts → consider `Hash Join` (may need more `work_mem`) - `Rows Removed by Filter` being high → index doesn't cover the filter - Actual rows far from estimated → run `ANALYZE tablename;` to update statistics ### Index Strategy ```sql -- Single column (most common) CREATE INDEX idx_orders_user_id ON orders(user_id); -- Composite (for queries filtering on both columns) CREATE INDEX idx_orders_user_status ON orders(user_id, status); -- Column ORDER matters: put equality filters first, range filters last -- Covering index (includes data columns to avoid table lookup) CREATE INDEX idx_orders_covering ON orders(user_id, status) INCLUDE (total, created_at); -- Partial index (smaller, faster — only index what you query) CREATE INDEX idx_orders_pending ON orders(user_id) WHERE status = 'pending'; -- Check unused indexes SELECT schemaname, tablename, indexname, idx_scan FROM pg_stat_user_indexes WHERE idx_scan = 0 AND indexname NOT LIKE '%pkey%' ORDER BY pg_relation_size(indexrelid) DESC; ``` ### SQLite EXPLAIN ```sql EXPLAIN QUERY PLAN SELECT * FROM orders WHERE user_id = 5; -- Look for: SCAN (bad) vs SEARCH USING INDEX (good) ``` ## Backup & Restore ### PostgreSQL ```bash # Full dump (custom format, compressed) pg_dump -Fc -h localhost -U myuser mydb > backup.dump # Restore pg_restore -h localhost -U myuser -d mydb --clean --if-exists backup.dump # SQL dump (portable, readable) pg_dump -h localhost -U myuser mydb > backup.sql # Dump specific tables pg_dump -h localhost -U myuser -t users -t orders mydb > partial.sql # Copy table to CSV psql -c "\copy (SELECT * FROM users) TO 'users.csv' CSV HEADER" ``` ### SQLite ```bash # Backup (just copy the file, but use .backup for consistency) sqlite3 mydb.sqlite ".backup backup.sqlite" # Dump to SQL sqlite3 mydb.sqlite .dump > backup.sql # Restore from SQL sqlite3 newdb.sqlite < backup.sql ``` ### MySQL ```bash # Dump mysqldump -h localhost -u root -p mydb > backup.sql # Restore mysql -h localhost -u root -p mydb < backup.sql ``` ## Tips - Always use parameterized queries in application code — never concatenate user input into SQL - Use `TIMESTAMPTZ` (not `TIMESTAMP`) in PostgreSQL for timezone-aware dates - Set `PRAGMA journal_mode=WAL;` in SQLite for concurrent read performance - Use `EXPLAIN` before deploying any query that runs on large tables - PostgreSQL: `\d+ tablename` shows columns, indexes, and size. `\di+` lists all indexes with sizes - For quick data exploration, import any CSV into SQLite: `sqlite3 :memory: ".mode csv" ".import file.csv t" "SELECT ..."`


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