From 4d0a5c0189e399d9fcc7e8078fb6a14fd243855a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9C=E5=AD=94=E5=87=AF=E8=BE=89=E2=80=9D?=
 <“2814283821@qq.com”>
Date: Sun, 19 Feb 2023 20:48:20 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BD=9C=E4=B8=9A?=
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 .../20230219 \344\275\234\344\270\232.md"     | 59 +++++++++++++++++++
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 create mode 100644 "44 \345\255\224\345\207\257\350\276\211/20230219 \344\275\234\344\270\232.md"

diff --git "a/44 \345\255\224\345\207\257\350\276\211/20230219 \344\275\234\344\270\232.md" "b/44 \345\255\224\345\207\257\350\276\211/20230219 \344\275\234\344\270\232.md"
new file mode 100644
index 0000000..4b16f63
--- /dev/null
+++ "b/44 \345\255\224\345\207\257\350\276\211/20230219 \344\275\234\344\270\232.md"	
@@ -0,0 +1,59 @@
+~~~mysql
+# 作业
+
+```sql
+
+create database test01_market;
+create table customers(
+    c_num int(11),
+    c_name varchar(50),
+    c_contact varchar(50),
+    c_city varchar(50),
+    c_birth date
+);
+alter table customers modify c_contact varchar(50) after c_birth;
+
+alter table customers modify c_name varchar(70);
+
+alter table customers change c_contact c_phone varchar(50);
+
+alter table customers add c_gender char(1);
+alter table customers modify c_gender char(1) after c_name;
+
+alter table customers rename to customers_info;
+# **要求8：**删除字段c_city
+alter table customers drop c_city;
+```
+
+```sql
+
+create database test02_library;
+
+create table books(
+    b_id int(11) not null primary key comment '书编号',
+    b_name varchar(50) not null comment '书名',
+    authors varchar(100)not null comment '作者',
+    price float not null comment '价格',
+    prbdate year not null comment '出版日期',
+    note varchar(100) null comment '说明',
+    num int(11) not null comment '库存'
+);
+
+insert into books values (1,'Tal of AAA','Dickes',23,1995,'novel',11);
+insert into books values (2,'EmmaT','Jane lura',35,1993,'joke',22);
+insert into books values (3,'Story of Jane','Jane Tim',40,2001,'novel',0),
+                         (4,'Lovey Day','George Byron',20,2005,'novel',30),
+                         (5,'Old land','Old land',30,2010,'law',0),
+                         (6,'The Battle','The Battle',30,1999,'medicine',40),
+                         (7,'Rose Hood','Rose Hood',28,2008,'cartoon',28);
+update books set price=+5 where note = 'novel';
+update books set price=40 where b_name='EmmaT';
+delete from books where num=0;
+```
+
+```sql
+
+```
+
+~~~
+
-- 
Gitee