sqlANYstringconcat
sql
SELECT first_name || ' ' || last_name AS full_name
FROM users;String concatenation syntax varies by dialect; CONCAT() is also widely available.
SQL Functions and Aggregation
Reference for string, date, numeric, conditional, null-handling, and aggregate SQL functions.
Export
Copy the compact sheet, download it, or print it.
Download
`D` dense toggle · `C` copy all
String Functions
Transform and search text values.
sqlANYstringupperlower
sql
SELECT UPPER(email) AS email_upper, LOWER(email) AS email_lower
FROM users;Useful for case-insensitive comparisons and normalized reporting.
sqlANYstringtrim
sql
SELECT TRIM(name) AS cleaned_name
FROM customers;LTRIM and RTRIM are also available in many engines.
sqlANYstringsubstring
sql
SELECT SUBSTRING(phone FROM 1 FOR 3) AS area_code
FROM contacts;Substring function syntax differs slightly across SQL dialects.
sqlANYstringreplace
sql
SELECT REPLACE(phone, '-', '') AS digits_only
FROM contacts;Handy for lightweight normalization.
Date and Time Functions
Work with dates, timestamps, and intervals.
sqlANYdatetimecurrent-datecurrent-timestamp
sql
SELECT CURRENT_DATE AS today, CURRENT_TIMESTAMP AS now_ts;These values are useful for auditing and reporting queries.
sqlANYdateextract
sql
SELECT
EXTRACT(YEAR FROM created_at) AS year_num,
EXTRACT(MONTH FROM created_at) AS month_num
FROM orders;Useful for grouping and reporting by calendar parts.
sqlANYdateinterval
sql
SELECT created_at, created_at + INTERVAL '7 days' AS plus_seven_days
FROM orders;Interval syntax varies slightly across engines.
sqlANYdatecast
sql
SELECT CAST(created_at AS DATE) AS created_date
FROM orders;Useful for daily rollups.
Conditional, NULL, and Conversion Functions
CASE, COALESCE, NULLIF, CAST, and type-safe expressions.
sqlANYcaseconditional
sql
SELECT order_id,
CASE
WHEN amount >= 1000 THEN 'large'
WHEN amount >= 100 THEN 'medium'
ELSE 'small'
END AS bucket
FROM orders;CASE is one of the most useful SQL expressions for reporting and categorization.
sqlANYcoalescenull-handling
sql
SELECT COALESCE(phone, mobile_phone, 'N/A') AS preferred_phone
FROM contacts;COALESCE is portable and common across SQL engines.
sqlANYnullifnull-handling
sql
SELECT revenue / NULLIF(order_count, 0) AS revenue_per_order
FROM daily_metrics;NULLIF is often used to avoid divide-by-zero errors.
sqlANYcastconversion
sql
SELECT CAST(total AS DECIMAL(12,2)) AS total_decimal
FROM invoices;Explicit casts make query intent clearer and avoid implicit conversion surprises.
Advanced Aggregation
Conditional aggregation and distinct counting.
sqlANYcount-distinctaggregation
sql
SELECT COUNT(DISTINCT customer_id) AS unique_customers
FROM orders;Distinct counts are common in analytics and business reporting.
sqlANYaggregationcasereporting
sql
SELECT
COUNT(*) AS total_orders,
SUM(CASE WHEN status = 'paid' THEN 1 ELSE 0 END) AS paid_orders,
SUM(CASE WHEN status = 'refunded' THEN 1 ELSE 0 END) AS refunded_orders
FROM orders;CASE inside aggregates is a staple reporting pattern.
sqlANYaggregationdatereporting
sql
SELECT CAST(created_at AS DATE) AS day, COUNT(*) AS total
FROM events
GROUP BY CAST(created_at AS DATE)
ORDER BY day;Very common for dashboards and time-series summaries.
More in SQL
SQL Indexing and Performance
Query tuning patterns with EXPLAIN, indexing, keyset pagination, deduplication, and optimization-oriented SQL recipes.
SQL Window Functions and CTEs
Use CTEs, recursive queries, ranking, running totals, partitions, and lag/lead patterns for analytical SQL.
SQL DDL and DML
Create and change schema objects, then insert, update, delete, merge, and manage transactional data changes.
SQL Joins and Subqueries
Advanced relational query patterns for joins, subqueries, EXISTS, IN, set operations, and correlated queries.
SQL Cheat Sheet
Core SQL syntax and patterns for querying, filtering, sorting, joining, grouping, and modifying data.