网站建设实训总结报告用php写wordpress

背景

物料存在多个版本，我们每次只需要使用最新的版本

问题

• 问题1：版本使用的是字符串，倒序排序，会导致 版本8 会排在版本11 前面
• 问题2：版本version字符串既有数字字符串，也有字母字符串

解决思路

• 对于数字字符串，需要将其转换成整数，
• 字母字符串则转换成对应的ASCII码值

SQL语句

原本语句

SELECT material_code AS material_code_in,material_name AS material_name_in,'' AS material_type_in,material_class_small AS material_class_small_in,material_class_big AS material_class_big_in,erp_code AS erp_code_in,version AS version_in,unit AS unit_inFROM tbl_material_info WHERE material_code IN ('P120','P525A','2070039115')

改写语句

WITH RankedMaterials AS (SELECT material_code AS material_code_in,material_name AS material_name_in,'' AS material_type_in,material_class_small AS material_class_small_in,material_class_big AS material_class_big_in,erp_code AS erp_code_in,version AS version_in,unit AS unit_in,ROW_NUMBER() OVER (PARTITION BY material_code ORDER BY CASE WHEN TRY_CAST(version AS INT) IS NOT NULL THEN TRY_CAST(version AS INT) ELSE ASCII(SUBSTRING(version, 1, 1)) -- 将字母字符串转换为对应的ASCII码值END DESC) AS rnFROM tbl_material_info WHERE material_code IN ('P120','P525A','2070039115')
)
SELECT material_code_in,material_name_in,material_type_in,material_class_small_in,material_class_big_in,erp_code_in,version_in,unit_in
FROM RankedMaterials
WHERE rn = 1;