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+---
+title: Use Lowercase Identifiers for Compatibility
+impact: MEDIUM
+impactDescription: Avoid case-sensitivity bugs with tools, ORMs, and AI assistants
+tags: naming, identifiers, case-sensitivity, schema, conventions
+---
+
+## Use Lowercase Identifiers for Compatibility
+
+PostgreSQL folds unquoted identifiers to lowercase. Quoted mixed-case identifiers require quotes forever and cause issues with tools, ORMs, and AI assistants that may not recognize them.
+
+**Incorrect (mixed-case identifiers):**
+
+```sql
+-- Quoted identifiers preserve case but require quotes everywhere
+CREATE TABLE "Users" (
+  "userId" bigint PRIMARY KEY,
+  "firstName" text,
+  "lastName" text
+);
+
+-- Must always quote or queries fail
+SELECT "firstName" FROM "Users" WHERE "userId" = 1;
+
+-- This fails - Users becomes users without quotes
+SELECT firstName FROM Users;
+-- ERROR: relation "users" does not exist
+```
+
+**Correct (lowercase snake_case):**
+
+```sql
+-- Unquoted lowercase identifiers are portable and tool-friendly
+CREATE TABLE users (
+  user_id bigint PRIMARY KEY,
+  first_name text,
+  last_name text
+);
+
+-- Works without quotes, recognized by all tools
+SELECT first_name FROM users WHERE user_id = 1;
+```
+
+Common sources of mixed-case identifiers:
+
+```sql
+-- ORMs often generate quoted camelCase - configure them to use snake_case
+-- Migrations from other databases may preserve original casing
+-- Some GUI tools quote identifiers by default - disable this
+
+-- If stuck with mixed-case, create views as a compatibility layer
+CREATE VIEW users AS SELECT "userId" AS user_id, "firstName" AS first_name FROM "Users";
+```
+
+Reference: [Identifiers and Key Words](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS)