Question 1

Why should I format SQL queries and what are the benefits?

Accepted Answer

Formatted SQL improves readability, maintenance, and debugging. Benefits: easier to understand complex queries (especially JOINs, subqueries), faster code reviews (teammates read formatted code quicker), catch errors visually (missing commas, parentheses), consistent style across team, easier git diffs (formatted changes are clearer), better documentation, learn SQL structure (formatting reveals query logic). Example: unformatted "SELECT a,b FROM t WHERE x=1 AND y=2" vs formatted with proper line breaks and indentation. Industry standard: uppercase keywords (SELECT, FROM, WHERE), indented subqueries and JOINs. This tool automatically formats to best practices.

Question 2

What are SQL formatting best practices and conventions?

Accepted Answer

Standard conventions: UPPERCASE keywords (SELECT, FROM, WHERE, JOIN, ORDER BY), lowercase or PascalCase for table/column names, indent subqueries and CASE statements, one column per line in SELECT (for long lists), JOIN conditions on separate lines, align ON/WHERE clauses, use table aliases for clarity (t1.column vs long_table_name.column), meaningful alias names. Line length: max 80-120 characters. Comments: -- for single line, /* */ for blocks. Trailing commas: after each column except last (easier to add/remove). This tool follows industry-standard SQL Style Guide with customizable options.

Question 3

How do I format complex SQL with JOINs and subqueries?

Accepted Answer

Structure with clear hierarchy: main SELECT at left margin, each JOIN indented one level, ON conditions indented under JOIN, subqueries indented within parentheses, CASE statements indented per clause. Example pattern: SELECT columns, FROM table1 t1, INNER JOIN table2 t2, ON t1.id = t2.id, WHERE condition. Subquery: SELECT * FROM (SELECT nested FROM inner) sub WHERE sub.x = 1. Align related clauses vertically. Use line breaks before major keywords (JOIN, WHERE, GROUP BY, HAVING, ORDER BY). This tool handles nested queries, CTEs (WITH clauses), and multiple JOINs with proper indentation.

Question 4

What is the difference between SQL dialects (MySQL, PostgreSQL, SQL Server)?

Accepted Answer

All use ANSI SQL standard but have dialect-specific features. MySQL: LIMIT for pagination, backticks for identifiers, CONCAT() for strings. PostgreSQL: advanced types (JSON, arrays, hstore), LIMIT/OFFSET, double quotes for identifiers, RETURNING clause. SQL Server: TOP for limiting, square brackets [identifiers], GETDATE(), ISNULL(). Oracle: ROWNUM, dual table, (+) for outer joins, TO_DATE(). SQLite: limited ALTER TABLE, AUTOINCREMENT. Keywords mostly same (SELECT, JOIN, WHERE), but functions and syntax details differ. This tool recognizes major dialects and formats accordingly with appropriate syntax highlighting.

Question 5

How do I handle long SELECT column lists and maintain readability?

Accepted Answer

Put each column on separate line for lists >3 columns. Align columns vertically. Use trailing commas (easier to add/remove columns). Group related columns with blank lines. Add comments for complex expressions. Example: SELECT id, name, email, created_at, COUNT(orders.id) AS order_count. For calculated fields: meaningful aliases. Star (*) acceptable for ad-hoc queries but specify columns in production (future-proof against table changes). Use table aliases for clarity: t1.id vs table_with_long_name.id. This tool auto-formats column lists with proper indentation and alignment.

Question 6

What are CTEs (Common Table Expressions) and how should I format them?

Accepted Answer

CTEs use WITH clause to create named temporary result sets, improving readability over nested subqueries. Syntax: WITH cte_name AS (SELECT ...) SELECT * FROM cte_name. Multiple CTEs: WITH cte1 AS (...), cte2 AS (...) SELECT .... Benefits: named intermediate results, recursive queries, better performance plans (sometimes). Format: WITH on separate line, CTE name + AS on next line, indented SELECT within parentheses, main query at same level as WITH. Recursive CTEs: WITH RECURSIVE for tree/hierarchy queries. This tool formats CTEs with proper nesting and indentation for maximum readability.

Question 7

How do I format CASE statements and conditional logic in SQL?

Accepted Answer

CASE statement formatting: CASE on first line, each WHEN/THEN on separate line, indented, ELSE indented same as WHEN, END aligned with CASE. Example: CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ELSE default END AS alias. For complex conditions: break to multiple lines. Searched vs simple: CASE expression WHEN value (simple) vs CASE WHEN condition (searched). Use meaningful aliases for CASE results. Nested CASE: indent additional level. Alternative: COALESCE() for NULL handling, IIF() in SQL Server. This tool automatically indents CASE statements with proper alignment.

Question 8

Should I use tabs or spaces for SQL indentation?

Accepted Answer

Spaces are recommended for consistency across editors and environments. Standard: 2 or 4 spaces per indentation level. Tabs vary by editor settings (2, 4, 8 spaces) causing alignment issues. Mix of tabs and spaces causes formatting chaos. Modern practice: configure editor to insert spaces when Tab key pressed (soft tabs). For teams: define in style guide and enforce with linters (SQLFluff, sql-formatter-cli). Git: consistent spacing prevents meaningless diffs. This tool uses 2-space indentation by default (configurable) ensuring consistent output across all users and platforms.

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