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通过cmd调用7z软件实现压缩和解压缩文件 压缩文件: public object CompressZipFile(string sourceFile, string destinationFile) { object resObj; Process process = new Process(); 阅读全文
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full join 空值填充 SELECT coalesce( NULL , 0) as tianchong FROM DUAL SELECT coalesce( '' , '0') as tianchong FROM DUAL SELECT A.M, coalesce(B.N, 'X') AS N 阅读全文
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full join ,left join ,right join,inner join 一、full join full join SELECT A.*, B.* FROM (SELECT 0 AS T1 FROM DUAL UNION SELECT 1 AS T1 FROM DUAL UNION 阅读全文
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SQL语句实现按照分组划分优先级 分组划分优先级 SELECT B.* FROM (SELECT A.color, A.P, row_number() over(partition by P order by color desc) rn FROM (SELECT 'red' AS color, ' 阅读全文
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Oracle中获取字符串下标、截取字符串 获取下标: SELECT INSTR('AAA-BBB-CCC-DDD', '-', 1, 1) as 字符位置 FROM dual 截取字符串: SELECT SUBSTR('AAA-BBB-CCC-DDD', 1, 3) as 截取字符串 FROM DU 阅读全文
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Java实现的三种字符串反转 第一种: public class Main { public static void main(String[] args) { String s1 = "asdfghjkl"; System.out.println(new StringBuilder(s1).rev 阅读全文