From 9e47826564c813110d68b61cbb532413753c10f0 Mon Sep 17 00:00:00 2001
From: iProbe <iprobe@noreply.localhost>
Date: Sun, 28 May 2023 10:16:55 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20'=E6=95=B0=E6=8D=AE?=
 =?UTF-8?q?=E5=BA=93/sql=E5=9F=BA=E7=A1=80.md'?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 数据库/sql基础.md | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 数据库/sql基础.md

diff --git a/数据库/sql基础.md b/数据库/sql基础.md
new file mode 100644
index 0000000..fc804b8
--- /dev/null
+++ b/数据库/sql基础.md
@@ -0,0 +1,44 @@
+## 1. 创建表
+```sql
+create table ttt(
+    no int primary key,
+    name char(10) not null,
+    depno int,
+    indate date,
+    sal numeric(8,2)
+);
+// numrtic(a,b): 数字类型，总位数为8，小数点后b位
+// char(a): 定长为a的字符串
+// varchar(a): 变长字符串，最大长度为a
+```
+## 2. 删除表
+```sql
+drop table ttt;
+drop table ttt if exists;
+```
+
+## 3. 插入
+```sql
+insert into ttt values(1,"ttt",1,"2023-05-28",12.33);
+insert into ttt(no,name,depno,indate,sal) values(1,"ttt",1,"2023-05-28",12.33);
+insert into ttt(no,name,depno) values(1,"ttt",1);
+```
+
+## 4. distinct去除重复
+```sql
+selet distinct depno from ttt;
+```
+## 5.查询多个值
+```sql
+select name from ttt where depno in (2,3,5);
+select name from ttt where depno not in (2,3,5);
+```
+
+## 6. between
+```sql
+select name from ttt where indate between '2022-01-22' and '2023-04-30';
+// 等价
+select name from ttt where indate>='2022-01-22' and indate<>='2023-04-30';
+
+select name from ttt where indate not between '2022-01-22' and '2023-04-30';
+```