-- user 表：企业微信客服接入链接（幂等；列已存在则跳过）
-- MySQL 5.7+ / 8.0

SET @db := DATABASE();

SET @col := (
  SELECT COUNT(*)
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = @db
    AND TABLE_NAME = 'user'
    AND COLUMN_NAME = 'WecomKfUrl'
);
SET @sql := IF(
  @col = 0,
  'ALTER TABLE `user` ADD COLUMN `WecomKfUrl` VARCHAR(512) NULL COMMENT ''企业微信客服接入链接''',
  'SELECT ''skip WecomKfUrl'' AS msg'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;