Custom SQL Query Guidelines
This guide provides best practices for writing well-structured SQL queries to improve readability, maintainability, and performance.
Formatting Instructions:
Use consistent indentation (2 or 4 spaces) for nested clauses.
Place each major SQL clause (SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY) on a new line.
Write SQL keywords in uppercase for clarity.
Align columns, conditions, and JOIN clauses vertically when appropriate.
Use aliases for all column names, table names, subqueries, and join tables with the
ASkeyword.Choose descriptive and meaningful aliases that accurately represent the data.
List each column on a separate line in the
SELECTclause when selecting multiple columns.Ensure proper spacing around operators and commas.
Use table aliases for all table references to improve query readability.
For database tenancy, replace all schema references with
{{DATABASE_NAME}}.
To apply these guidelines to different SQL environments, refer to the sections below:
Redshift
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (")
Always use double quotes for column, table, and subquery names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
Example Use Case
SELECT
SUM("listing_data"."totalprice") AS "sum_of_totalprice", -- ✔ Column Alias with Double Quotes
"public_category"."catname" AS "catname", -- ✔ Column Alias with Double Quotes
"public_event"."eventname" AS "eventname" -- ✔ Column Alias with Double Quotes
FROM
"{{DATABASE_NAME}}"."category" AS "public_category" -- ✔ Table Alias with Double Quotes and Database Reference
INNER JOIN "{{DATABASE_NAME}}"."event" AS "public_event" -- ✔ Join Table Alias with Double Quotes and Database Reference
ON "public_category"."catid" = "public_event"."catid"
INNER JOIN (
SELECT
"listing"."eventid" AS "eventid", -- ✔ Column Alias with Double Quotes
"listing"."totalprice" AS "totalprice" -- ✔ Column Alias with Double Quotes
FROM
"{{DATABASE_NAME}}"."listing" AS "listing" -- ✔ Table Alias with Double Quotes and Database Reference
) AS "listing_data"
ON "public_event"."eventid" = "listing_data"."eventid"
GROUP BY
"public_category"."catname",
"public_event"."eventname"Snowflake
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (")
Always use double quotes for column names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
Example Use Case
SELECT
SUM("databrain_dev2_demo_sales"."quantity sold") AS "sum of quantity sold", -- ✔ Column Alias with Double Quotes
"databrain_dev2_demo_sales"."client name" AS "client name" -- ✔ Column Alias with Double Quotes
FROM
"databrain_dev2"."demo_sales" AS databrain_dev2_demo_sales -- ✔ Table Alias (No Quotes)
INNER JOIN (
SELECT
"customer id",
"sales representative id"
FROM "databrain_dev2"."customer_data"
) AS databrain_dev2_customer_data -- ✔ Subquery Alias (No Quotes)
ON "databrain_dev2_demo_sales"."client name" = "databrain_dev2_customer_data"."customer id"
GROUP BY
"databrain_dev2_demo_sales"."client name"BigQuery
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (`)
Always use backticks for column names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
SELECT
SUM(`databrain_dev2_demo_sales`.`quantity sold`) AS `sum of quantity sold`, -- Column Alias with Backtiks
`databrain_dev2_demo_sales`.`client name` AS `client name` -- Column Alias with Backtiks
FROM
`databrain_dev2`.`demo_sales` AS databrain_dev2_demo_sales -- Table Alias (NO BACKTICKS)
INNER JOIN (
SELECT
`customer id`,
`sales representative id`
FROM `databrain_dev2`.`customer_data`
) AS databrain_dev2_customer_data -- Subquery Alias (NO BACKTICKS)
ON `databrain_dev2_demo_sales`.`client name` = `databrain_dev2_customer_data`.`customer id`
GROUP BY
`databrain_dev2_demo_sales`.`client name`
MySQL
Guideline 1: Use clear and consistent formatting
Guideline 2: Write precise queries
Guideline 3: Utilize column aliases
Example Use Case
SELECT
c.customer_id,
CONCAT(c.last_name, ', ', c.first_name) AS customer_name, -- ✔ Using column alias
a.phone,
f.title AS rented_film -- ✔ Using column alias
FROM
rental r
INNER JOIN customer c ON r.customer_id = c.customer_id -- ✔ Clear formatting with JOIN on new line
INNER JOIN address a ON c.address_id = a.address_id -- ✔ Consistent indentation
INNER JOIN inventory i ON r.inventory_id = i.inventory_id
INNER JOIN film f ON i.film_id = f.film_id
WHERE
r.return_date IS NULL -- ✔ Precise filtering
AND r.rental_date + INTERVAL f.rental_duration DAY < CURRENT_DATE() -- ✔ Specific condition
ORDER BY
c.last_name, c.first_name -- ✔ Major clause on new line
LIMIT 5; -- ✔ Precise result set size
PostgreSQL
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (")
Always use double quotes for column, table, and subquery names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
Example Use Case
SELECT
COUNT("public_posts"."user_id") AS "count of user_id", -- Column Alias with Double Quotes
"public_users"."username" AS "username"
FROM
"public"."users" AS "public_users" -- Table Alias with Double Quotes & Database Reference
INNER JOIN (
SELECT
"user_id",
"id" AS "post_id"
FROM "public"."posts"
) AS "public_posts" -- Subquery Alias with Double Quotes
ON "public_users"."id" = "public_posts"."user_id"
GROUP BY
"public_users"."username"
MongoDB
Guideline 1: Use proper syntax for MongoDB collections and fields
When querying MongoDB with SQL, wrap collection names and field names in square brackets to avoid syntax errors.
Guideline 2: Utilize projections to return only necessary data
This improves query performance by limiting the amount of data transferred and processed.
Guideline 3: Leverage indexing for frequently queried fields
Create indexes on commonly searched fields to significantly enhance query performance
SELECT [first_name], [last_name], [address.city], [transactions]
FROM [Customers]
WHERE [author_name] = 'John Doe'
ORDER BY [timestamp] DESC
LIMIT 10
Elasticsearch
Guideline 1: Ensure proper indexing and mapping
Correctly index and map your data to optimize query efficiency. SQL utilizes Elasticsearch's indexing and mapping functionalities, so the effectiveness of your queries is directly influenced by accurate data organization.
Guideline 2: Utilize projections to return only necessary data
This improves query performance by limiting the amount of data transferred and processed. Use SQL's SELECT statement to specify only the required fields.
Guideline 3: Leverage Elasticsearch SQL optimizations
Take advantage of query rewriting, caching, and parallel execution to enhance the efficiency of your queries.
SELECT [first_name], [last_name], [address.city]
FROM [customers]
WHERE [created_at] BETWEEN '2025-01-01' AND '2025-03-20'
AND [status] = 'active'
ORDER BY [last_login] DESC
LIMIT 10
Databricks
Guideline 1: Use specific column names instead of SELECT *
This reduces the amount of data processed and transferred, speeding up queries.
Guideline 2: Utilize WHERE clauses to filter rows early
This reduces the number of rows processed in later stages of the query, improving performance.
Guideline 3: Implement proper indexing
Create indexes on frequently queried columns to drastically improve query performance.
SELECT o.order_id, c.customer_name, o.order_total
FROM orders o
JOIN customers c ON o.customer_id = c.customer_id
WHERE o.order_date >= '2025-01-01' AND o.order_date <= '2025-03-20'
AND c.region = 'North America'
ORDER BY o.order_date DESC
LIMIT 10
MSSQL
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (")
Always use double quotes for column, table, and subquery names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
Example Use Case
SELECT
TOP 100 "dbn_sql_table"."name" AS "name",
"dbn_sql_table"."available" AS "available"
FROM
(
SELECT
TOP 100 "dbo_person"."name" AS "name", -- ✔ Column Alias with Double Quotes
"dbo_pizza_topping"."available" AS "available" -- ✔ Column Alias with Double Quotes
FROM
"dbo"."person" AS "dbo_person" -- ✔ Table Alias with Double Quotes & Database Reference
INNER JOIN (
SELECT
"id",
"available"
FROM
"dbo"."pizza_topping"
) AS "dbo_pizza_topping" -- Subquery Alias
ON "dbo_person"."person_id" = "dbo_pizza_topping"."id"
) AS "dbn_sql_table"AwsS3
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (")
Always use double quotes for column, table, and subquery names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
Example Use Case
SELECT
"main_orders"."order_id" AS "Order ID", -- ✔ Column Alias & Double Quotes
"main_customers"."first_name" AS "First Name", -- ✔ Column Alias & Double Quotes
"main_customers"."last_name" AS "Last Name", -- ✔ Column Alias & Double Quotes
"main_coffees"."name" AS "Coffee Name", -- ✔ Column Alias & Double Quotes
"main_orders"."quantity" AS "Quantity" -- ✔ Column Alias & Double Quotes
FROM
"main"."orders" AS "main_orders" -- ✔ Table Alias, Database Reference & Double Quotes
JOIN "main"."customers" AS "main_customers" -- ✔ Join Table Alias, Database Reference & Double Quotes
ON "main_orders"."customer_id" = "main_customers"."customer_id"
JOIN "main"."coffees" AS "main_coffees" -- ✔ Join Table Alias, Database Reference & Double Quotes
ON "main_orders"."coffee_id" = "main_coffees"."coffee_id"
JOIN (
SELECT
"main_orders"."customer_id" AS "customer_id", -- ✔ Column Alias & Double Quotes
SUM("main_orders"."quantity" * "main_coffees"."price") AS "Amount Spent" -- ✔ Column Alias & Double Quotes
FROM
"main"."orders" AS "main_orders" -- ✔ Table Alias, Database Reference & Double Quotes
JOIN "main"."coffees" AS "main_coffees" -- ✔ Join Table Alias, Database Reference & Double Quotes
ON "main_orders"."coffee_id" = "main_coffees"."coffee_id"
GROUP BY
"main_orders"."customer_id"
) AS "sq" -- ✔ Subquery Alias & Double Quotes
ON "main_orders"."customer_id" = "sq"."customer_id"Firebolt
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Double Quotes (")
Always use double quotes for column, table, and subquery names to avoid conflicts with reserved keywords and case-sensitive identifiers.
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
Example Use Case
SELECT
SUM("public_levels"."maxpoints") AS "sum of maxpoints", -- ✔ Column Alias with Double Quotes
"public_games"."title" AS "title", -- ✔ Column Alias with Double Quotes
COUNT("public_rankings"."playerid") AS "num_players" -- ✔ Column Alias with Double Quotes
FROM
"public"."games" AS "public_games" -- ✔ Table Alias with Double Quotes & Database Reference
INNER JOIN "public"."levels" AS "public_levels" -- ✔ Join Table Alias with Double Quotes & Database Reference
ON "public_games"."gameid" = "public_levels"."gameid"
INNER JOIN (
SELECT DISTINCT "gameid", "playerid"
FROM "public"."rankings"
WHERE "totalscore" > 0
) AS "public_rankings" -- Subquery with Alias
ON "public_games"."gameid" = "public_rankings"."gameid"
GROUP BY
"public_games"."title"
SingleStore
Guideline 1: Use Aliases for Readability
Always use aliases for column names, table names, subqueries, and join tables using the AS keyword. Aliases improve readability and make queries more concise.
Guideline 2: Enclose Identifiers in Backticks (`)
Database names, table names, and column names should be enclosed in backticks (`).
Guideline 3: Reference Tables with the Database Name
Always prefix tables with the database and schema name to ensure clarity, especially in multi-schema databases.
SELECT
SUM(`public_levels`.`maxpoints`) AS `sum_of_maxpoints`, -- ✔ Column Alias with Backticks
`public_games`.`title` AS `title`, -- ✔ Column Alias with Backticks
COUNT(`public_rankings`.`playerid`) AS `num_players` -- ✔ Column Alias with Backticks
FROM
`public`.`games` AS `public_games` -- ✔ Table Alias with Backticks & Database Reference
INNER JOIN `public`.`levels` AS `public_levels` -- ✔ Join Table Alias with Backticks & Database Reference
ON `public_games`.`gameid` = `public_levels`.`gameid`
INNER JOIN (
SELECT DISTINCT `gameid`, `playerid`
FROM `public`.`rankings`
WHERE `totalscore` > 0
) AS `public_rankings` -- Subquery with Alias
ON `public_games`.`gameid` = `public_rankings`.`gameid`
GROUP BY
`public_games`.`title`;
To automatically correct and format your SQL query, click on the magic stick icon next to the "Format Query" button.
This ensures proper syntax, indentation, and readability.
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