在 WHERE 子句中使用下标

您可以在 SELECT 语句的 WHERE 子句中使用下标，以指定选择某列中一定范围内额字符或数字，如下所示。

SELECT catalog_num, stock_num, manu_code, cat_advert,
          cat_descr
          FROM catalog
          WHERE cat_advert[1,4] = 'High';

下标 [1,4] 导致该查询检索 cat_advert 列的前四个字母为 High 的所有行。如下所示。

图: 查询结果

catalog_num  10004
            stock_num    2
            manu_code    HRO
            cat_advert   Highest Quality Ball Available, from Hand-Sti
            tching to the Robinson Signature
            cat_descr    
            Jackie Robinson signature ball. Highest professional quality, 
            used by National League.
            
            catalog_num  10005
            stock_num    3
            manu_code    HSK
            cat_advert   High-Technology Design Expands the Sweet Spot
            cat_descr    
            Pro-style wood. Available in sizes: 31, 32, 33, 34, 35.
            ⋮
            catalog_num  10045
            stock_num    204
            manu_code    KAR
            cat_advert   High-Quality Beginning Set of Irons. Appropriate
            for High School Competitions
            cat_descr    
            Ideally balanced for optimum control. Nylon covered shaft.
            
            catalog_num  10068
            stock_num    310
            manu_code    ANZ
            cat_advert   High-Quality Kickboard
            cat_descr    
            White. Standard size.