-- 当前企微标签目录需要按 external_userid 判断客户是否仍有效。
-- 覆盖 external_userid + delete_time，避免标签聚合逐条回表读取体积较大的客户 JSON 数据。
SET @idx_external_delete_exists := (
    SELECT COUNT(*)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = DATABASE()
      AND TABLE_NAME = 'zyt_qywx_external_contact'
      AND INDEX_NAME = 'idx_external_delete'
);

SET @add_idx_external_delete_sql := IF(
    @idx_external_delete_exists = 0,
    'ALTER TABLE `zyt_qywx_external_contact` ADD INDEX `idx_external_delete` (`external_userid`, `delete_time`)',
    'SELECT 1'
);

PREPARE add_idx_external_delete_stmt FROM @add_idx_external_delete_sql;
EXECUTE add_idx_external_delete_stmt;
DEALLOCATE PREPARE add_idx_external_delete_stmt;