From 6ad8a33e997a2f05bb73db32bb489ec0d6bfbc0f Mon Sep 17 00:00:00 2001
From: xuxin <840198532@qq.com>
Date: Sun, 11 Oct 2026 12:01:55 +0800
Subject: [PATCH] =?UTF-8?q?javaEEday07-DQL-Select-=E5=9F=BA=E6=9C=AC?=
 =?UTF-8?q?=E6=9F=A5=E8=AF=A2?=
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---
 mysql-day02.sql | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/mysql-day02.sql b/mysql-day02.sql
index 8ce0b16..b6d9ff8 100644
--- a/mysql-day02.sql
+++ b/mysql-day02.sql
@@ -17,7 +17,7 @@ create table tb_emp
         unique (username)
 )
     comment '员工表';
-
+-- ========================================基本查询==========================================
 -- DML:数据操作语言
 -- DML : 插入数据 - insert
 -- 1. 为 tb_emp 表的 username, name, gender 字段插入值
@@ -57,4 +57,28 @@ update tb_emp set entrydate='2010-01-01',update_time=now();
 delete from tb_emp where id = 1;
 
 -- 2. 删除 tb_emp 表中的所有员工
-delete from tb_emp;
\ No newline at end of file
+delete from tb_emp;
+
+-- ======================================DQL===================================
+-- 基本查询
+-- 1. 查询指定字段 name,entrydate 并返回
+select name,entrydate from tb_emp;
+
+-- 2. 查询返回所有字段
+-- 方式一:  推荐 , 效率高 . 更直观
+select  id, username, password, name, gender,
+        image, job, entrydate, dept_id,
+        create_time, update_time from tb_emp;
+
+-- 方式二:不推荐（不直观，性能低）
+select * from tb_emp;
+
+-- 3. 查询所有员工的 name,entrydate, 并起别名(姓名、入职日期)  --- as 关键字可以省略
+select name as '姓名',entrydate as '入职日期' from tb_emp;
+
+select name  '姓名',entrydate  '入职日期' from tb_emp;
+
+-- 4. 查询员工有哪几种职位(不要重复) -- distinct
+select distinct job from tb_emp;
+
+