Conditional & Cast Functions

SQL · Methods reference

SQL · Methods reference

📋 Overview

Branching logic, NULL handling, and type conversion in SQL.

🔧 Methods

Conditional & null

Function	Description
`CASE WHEN … THEN … ELSE … END`	Conditional expression
`COALESCE(a, b, …)`	First non-NULL argument
`NULLIF(a, b)`	NULL if a equals b
`IF(cond, a, b)` (MySQL)	Simple conditional
`GREATEST(a,b,…)` / `LEAST`	Max/min of args

Cast & JSON

Function	Description
`CAST(x AS type)`	Standard cast
`x::type` (PG)	Postgres cast shorthand
`JSON_EXTRACT` (MySQL) / `->` / `->>` (PG)	JSON path access
`JSON_BUILD_OBJECT` / `JSON_AGG` (PG)	Build JSON in SQL

💡 Examples

See parent topic notes for runnable snippets; this page is the complete method index.

⚠️ Pitfalls

Mutating methods return None in Python — do not chain sort() / reverse() expecting a new list.
Default JS sort() compares strings — pass (a,b) => a-b for numbers.
SQL function names differ by dialect — verify Postgres vs MySQL docs.
Django QuerySet.update() skips save() signals and auto auto_now fields on models.

Aggregate Functions

SQL · Methods reference

Date & Time Functions

SQL · Methods reference

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📋 Overview 🔧 Methods Conditional & null Cast & JSON 💡 Examples ⚠️ Pitfalls 🔗 Related