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| SET @column_exists := (
| SELECT COUNT(1)
| FROM information_schema.COLUMNS
| WHERE TABLE_SCHEMA = DATABASE()
| AND TABLE_NAME = 't_parking_lot'
| AND COLUMN_NAME = 'barrier_brand'
| );
|
| SET @ddl := IF(
| @column_exists = 0,
| 'ALTER TABLE `t_parking_lot` ADD COLUMN `barrier_brand` int NULL DEFAULT NULL COMMENT ''道闸品牌：1舜杰，2捷联'' AFTER `type`',
| 'SELECT 1'
| );
|
| PREPARE stmt FROM @ddl;
| EXECUTE stmt;
| DEALLOCATE PREPARE stmt;
|
| UPDATE `t_parking_lot`
| SET `barrier_brand` = 2
| WHERE `barrier_brand` IS NULL;
|
|
