2.查询满足条件的元组 查询条件 谓词 比较运算符 >,,,心(或=) NOT+比较运算符 确定范围 BETWEEN. AND NOT BETWEEN. AND 确定集合 IN NOTIN 字符匹配 LIKE. NOT LIKE 空值 IS NULL IS NOT NULL 逻辑谓词) AND OR2. 查询满足条件的元组 查询条件 谓 词 比较运算符 =, >, >=, <, <=, <>（或!=） NOT+比较运算符 确定范围 BETWEEN…AND, NOT BETWEEN…AND 确定集合 IN, NOT IN 字符匹配 LIKE, NOT LIKE 空值 IS NULL, IS NOT NULL 逻辑谓词） AND, OR