sql-querieslisted
Install: claude install-skill Safen99/opencode-cowork-plugins
# SQL Queries Skill
Write correct, performant, readable SQL across all major data warehouse dialects.
## Dialect-Specific Reference
### PostgreSQL (including Aurora, RDS, Supabase, Neon)
**Date/time:**
```sql
-- Current date/time
CURRENT_DATE, CURRENT_TIMESTAMP, NOW()
-- Date arithmetic
date_column + INTERVAL '7 days'
date_column - INTERVAL '1 month'
-- Truncate to period
DATE_TRUNC('month', created_at)
-- Extract parts
EXTRACT(YEAR FROM created_at)
EXTRACT(DOW FROM created_at) -- 0=Sunday
-- Format
TO_CHAR(created_at, 'YYYY-MM-DD')
```
**String functions:**
```sql
-- Concatenation
first_name || ' ' || last_name
CONCAT(first_name, ' ', last_name)
-- Pattern matching
column ILIKE '%pattern%' -- case-insensitive
column ~ '^regex_pattern$' -- regex
-- String manipulation
LEFT(str, n), RIGHT(str, n)
SPLIT_PART(str, delimiter, position)
REGEXP_REPLACE(str, pattern, replacement)
```
**Arrays and JSON:**
```sql
-- JSON access
data->>'key' -- text
data->'nested'->'key' -- json
data#>>'{path,to,key}' -- nested text
-- Array operations
ARRAY_AGG(column)
ANY(array_column)
array_column @> ARRAY['value']
```
**Performance tips:**
- Use `EXPLAIN ANALYZE` to profile queries
- Create indexes on frequently filtered/joined columns
- Use `EXISTS` over `IN` for correlated subqueries
- Partial indexes for common filter conditions
- Use connection pooling for concurrent access
---
### Snowflake
**Date/time:**
```sql
-- Current date/time
CURRENT_DATE(), CURRENT_TIMESTAMP(), S