-- 直播场次补充视频时长字段，兼容历史数据允许为空。
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SET @duration_seconds_column_exists = (
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SELECT COUNT(*)
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FROM information_schema.COLUMNS
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WHERE TABLE_SCHEMA = DATABASE()
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AND TABLE_NAME = 'tcm_live_session'
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AND COLUMN_NAME = 'duration_seconds'
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);
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SET @duration_seconds_alter_sql = IF(
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@duration_seconds_column_exists = 0,
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'ALTER TABLE `tcm_live_session` ADD COLUMN `duration_seconds` INT DEFAULT NULL COMMENT ''视频时长（秒）'' AFTER `video_url`',
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'SELECT 1'
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);
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PREPARE duration_seconds_stmt FROM @duration_seconds_alter_sql;
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EXECUTE duration_seconds_stmt;
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DEALLOCATE PREPARE duration_seconds_stmt;
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