mysql判断表字段或索引是否存在，然后修改

判断字段是否存在：

DROP PROCEDURE IF EXISTS schema_change;  
DELIMITER //
CREATE PROCEDURE schema_change() BEGIN 
DECLARE  CurrentDatabase VARCHAR(100);
SELECT DATABASE() INTO CurrentDatabase;
IF NOT EXISTS (SELECT * FROM information_schema.columns WHERE table_schema=CurrentDatabase AND table_name = 'rtc_order' AND column_name = 'IfUpSend') THEN  
    ALTER TABLE rtc_order
    ADD COLUMN `IfUpSend` BIT  NOT NULL  DEFAULT 0 COMMENT '是否上传 是否上传';
END IF;  
END//  
DELIMITER ;  
CALL schema_change();

判断索引是否存在：

DROP PROCEDURE IF EXISTS schema_change;  
DELIMITER //
CREATE PROCEDURE schema_change() BEGIN 
DECLARE  CurrentDatabase VARCHAR(100);
SELECT DATABASE() INTO CurrentDatabase;
IF NOT EXISTS (SELECT * FROM information_schema.statistics WHERE table_schema=CurrentDatabase AND table_name = 'rtc_phototype' AND index_name = 'index_name') THEN  
   ALTER TABLE `rtc_Phototype` ADD INDEX index_name ( `imgtype` );
END IF;  
END//  
DELIMITER ;  
CALL schema_change();