在mysql中可以使用下面的语句判断mysql表中字段是否存在：
select count(*) from information_schema.columns where table_name = '表名' and column_name = '字段名'
示例：
-- ---------------------------- -- 判断 vrv_paw_rule 表是否存在 thresholdMin 字段，不存在则添加; 存在则修改字段类型 DELIMITER ?? DROp PROCEDURE IF EXISTS schema_change?? CREATE PROCEDURE schema_change() BEGIN IF NOT EXISTS (SELECT * FROM information_schema.columns WHERe table_schema = DATABASE() AND table_name = 'vrv_paw_rule' AND column_name = 'thresholdMin') THEN ALTER TABLE vrv_paw_rule ADD COLUMN thresholdMin BIGINT; ELSE ALTER TABLE vrv_paw_rule MODIFY COLUMN thresholdMin BIGINT ; END IF; END?? DELIMITER ; CALL schema_change();
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