mysql 判断表字段或索引是否存在

判断字段是否存在：

 DROP PROCEDURE IF EXISTS schema_change;
  DELIMITER //
  CREATE PROCEDURE schema_change() BEGIN
  DECLARE  CurrentDatabase VARCHAR();
  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  COMMENT '是否上传 是否上传';
  END IF;
 END//
 DELIMITER ;
 CALL schema_change();

判断索引是否存在：

 1 DROP PROCEDURE IF EXISTS schema_change;
 2 DELIMITER //
 3 CREATE PROCEDURE schema_change() BEGIN
 4 DECLARE  CurrentDatabase VARCHAR(100);
 5 SELECT DATABASE() INTO CurrentDatabase;
 6 IF NOT EXISTS (SELECT * FROM information_schema.statistics WHERE table_schema=CurrentDatabase AND table_name = 'rtc_phototype' AND index_name = 'index_name') THEN
 7    ALTER TABLE `rtc_Phototype` ADD INDEX index_name ( `imgtype` );
 8 END IF;
 9 END//
10 DELIMITER ;
11 CALL schema_change(); 

从这两段代码可以举一反三，可以得知很多信息，具体可以自己试验一下