题目链接 戳这里 题解 语法:SELECT 列名1, 列名2... FROM 表名 SELECT device_id, gender, age, university FROM user_profile
思路:要取出的列是表的其中一些列,所以要明确命名。 代码解释:从表user_profile 中取出列 device_id、gender、age、university SELECT device_id, gender, age, university FROM user_profile; 题目:https://www.nowcoder.com/practice/499b6d01eae342b2aa
题目:https://www.nowcoder.com/practice/c60242566ad94bc29959de0cdc6d95ef?tpId=268&tqId=2285039&ru=/exam/oj&qru=/ta/sql-factory-interview/question-ranking&sourceUrl=%2Fexam%2Foj%3Fpage%3D1%26tab%3DSQL%25E7%25AF%2587%26topicId%3D268 方法1: s
create database db_mydb; --创建数据库create database db_mydbon(name='mydb',filename='e:\db_mydb.mdf',size=10,maxsize=50,filegrowth=5) --创建日志文件log on(name='mydb_log',filename='e:\db_mydb_log.ldf',size=3,maxsize=20,fileg
//通用表插入 public static <T> int insertTableList(Connection connection, String tableName, T t){ int flag = -1; QueryRunner queryRunner = new QueryRunner(); Class c=t.getClass(); String sql = "insert into "+
select * from employees where hire_date = (select distinct hire_date from employees order by hire_date desc limit 1 offset 2)
SELECT * FROM employees WHERE hire_date = ( SELECT DISTINCT hire_date FROM employees ORDER BY hire_date DESC #-- 倒序 LIMIT 1 OFFSET 2 #-- 去掉排名倒数第一第二的时间,取倒数第三 ); # #limit和offset用法 # # mysql里分页一般用lim
$str=‘ximing’; s q l 2 = " I N
数据库的删除: PreparedStatement psql; //预处理数据 String sql1="delete from stu where id=452676"; //sql删除语句 psql=con.prepareStatement(sql1); //执行预处理语句 psql.executeUpdate(); //更新数据 psql
sql2slack对于slack 的处理是通过http 请求的,默认已经固定了格式了,以下是一个简单的修改,可以方便的支持钉钉webhook消息 而且具有通用性 需要修改部分 主要是关于使用resty 处理http 请求的部分,默认是写死的,可以修改为 job.go // _, err = resty.New().R().Se
索引: 添加索引: 主键也属于索引
libname clinic 'E:\sas'; data admit; set sasuser.admit; run; proc sql; select name, sex , age, height from sasuser.admit where (actlevel='LOW' and height>70) or age>35 order by sex desc ,height asc;
USE [web1]GO/****** Object: StoredProcedure [dbo].[GetPageList] Script Date: 08/22/2014 15:02:14 ******/SET ANSI_NULLS ONGOSET QUOTED_IDENTIFIER ONGOAlter PROCEDURE [dbo].[GetPageList] @TableName varchar(20), @IdName varchar(10), @pageSize int, @pageI
TynSerial序列(还原)TClientDataSet 可以一次性序列(还原)多个TClientDataSet。 procedure TForm1.Qrys(accountno, sql, sql2: string; DataSet, DataSet2: TClientDataSet);// TClientDataSet主从表查询var url: SockString; i: integer; serial: TynSerial;begin serial := Tyn
主要整理了关系模型用到的一些基本概念,总的来说还是在做铺垫。
//质量之星 select b.user_name as userName, c.expert_id as expertId, b.user_photo as userHeadIcon, amout as codeSum, rn as rank from user_info b,( select expert_id,amout,row_number() over(order by amout desc) as rn from( select expert_id, count(expert_id)