#MySQL更新数据

-- Update single column

-- Update multiple columns

-- Update all rows

-- Update with condition

-- Update based on another column

-- Update specific row

-- Update based on value

-- Update with OR condition

-- Update with IN

-- Update with subquery

-- Update with ORDER BY

-- Update first 10 inactive users

-- Update with ORDER BY and LIMIT (MySQL 8.0+)

-- Increment

-- Decrement

-- Multiply

-- Complex calculation

-- Concatenate

-- Replace

-- Update substring

-- Change case

-- Add interval

-- Set to current timestamp

-- Date arithmetic

-- Update based on another table

-- Update using LEFT JOIN

-- Update from multiple tables

-- Update with correlated subquery

-- Update with EXISTS

-- Update based on condition

-- Update priority

-- Simple conditional update

-- Multiple IF

-- DANGEROUS: Updates all rows

-- SAFE: With WHERE clause

-- Create backup table

-- Or use transaction (for InnoDB)
-- Verify changes
-- COMMIT; or ROLLBACK;

-- Add LIMIT to control affected rows

-- Use SELECT to verify first

-- Get updated values

-- With affected rows

-- Deactivate old records

-- Approve pending records

-- Increment counter

-- Decrement stock

-- Reset counters daily

-- Apply discount

-- Increase prices

-- No rows affected
-- Check: WHERE condition, data types

-- Duplicate key error
-- Check: UNIQUE constraints

-- Foreign key constraint error
-- Check: Related tables

-- Data truncation
-- Check: Column sizes, data types

-- Test with SELECT first

-- Check affected rows

-- Verify changes