Merge pull request #120 from GuoXiCheng/dev-c

update docs

src/.vitepress/sidebars/sqlite.yaml

@@ -62,5 +62,27 @@
             link: /database/sqlite/core-concepts/update-statement#更新所有行
           - text: 更新指定行
             link: /database/sqlite/core-concepts/update-statement#更新指定行
+      - text: Select 语句
+        link: /database/sqlite/core-concepts/select-statement
+        items:
+          - text: 基本语法
+            link: /database/sqlite/core-concepts/select-statement#基本语法
+          - text: Where 子句
+            link: /database/sqlite/core-concepts/select-statement#where-子句
+            items:
+              - text: 比较
+                link: /database/sqlite/core-concepts/select-statement#比较
+              - text: 逻辑
+                link: /database/sqlite/core-concepts/select-statement#逻辑
+              - text: IN
+                link: /database/sqlite/core-concepts/select-statement#in
+              - text: Between And
+                link: /database/sqlite/core-concepts/select-statement#between-and
+              - text: Exists
+                link: /database/sqlite/core-concepts/select-statement#exists
+              - text: Is Null
+                link: /database/sqlite/core-concepts/select-statement#is-null
+          - text: Like 子句
+            link: /database/sqlite/core-concepts/select-statement#like-子句
 
 

src/database/sqlite/core-concepts/select-statement.md

@@ -0,0 +1,167 @@
+# Select 语句
+
+## 基本语法
+
+::: code-group
+
+```sql [语法]
+SELECT column1, column2, ...
+FROM table_name;
+```
+
+```sql [实例]
+SELECT name, age
+FROM students;
+```
+
+:::
+
+## Where 子句
+
+### 比较
+
+::: code-group
+
+```sql [大于]
+select * from students where age > 20;
+```
+
+```sql [小于]
+select * from students where age < 20;
+```
+
+```sql [大于等于]
+select * from students where age >= 20;
+```
+
+```sql [小于等于]
+select * from students where age <= 20;
+```
+
+```sql [等于]
+select * from students where age = 20;
+```
+
+```sql [不等于]
+select * from students where age != 20;
+```
+
+:::
+
+### 逻辑
+
+::: code-group
+
+```sql [AND]
+select * from students where age > 20 and name = 'John';
+```
+
+```sql [OR]
+select * from students where age > 20 or name = 'John';
+```
+
+```sql [NOT]
+select * from students where not age > 20;
+```
+
+:::
+
+### IN
+
+::: code-group
+
+```sql [IN]
+select * from students where age in (20, 21, 22);
+```
+
+```sql [NOT IN]
+select * from students where age not in (20, 21, 22);
+```
+
+:::
+
+### Between And
+
+::: code-group
+
+```sql [BETWEEN]
+select * from students where age between 20 and 30;
+```
+
+```sql [NOT BETWEEN]
+select * from students where age not between 20 and 30;
+```
+
+:::
+
+### Exists
+
+::: code-group
+
+```sql [EXISTS]
+select * from students where exists (
+    select * from teachers where students.teacher_id = teachers.id
+);
+```
+
+```sql [NOT EXISTS]
+select * from students where not exists (
+    select * from teachers where students.teacher_id = teachers.id
+);
+```
+
+:::
+
+### Is Null
+
+::: code-group
+
+```sql [IS NULL]
+select * from students where name is null;
+```
+
+```sql [IS NOT NULL]
+select * from students where name is not null;
+```
+
+:::
+
+## Like 子句
+
+Like 用来匹配通配符指定模式的文本值。
+
+Like 通常与两个通配符一起使用：
+
+- 百分号（%）：代表零个、一个或多个字符。
+- 下划线（\_）：代表一个单一的字符。
+
+::: code-group
+
+```sql [LIKE]
+select * from students where name like 'J%';
+```
+
+```sql [NOT LIKE]
+select * from students where name not like 'J%';
+```
+
+```sql [LIKE]
+select * from students where name like 'J_n';
+```
+
+```sql [NOT LIKE]
+select * from students where name not like 'J_n';
+```
+
+:::
+
+| 语句                        | 描述                                |
+| --------------------------- | ----------------------------------- |
+| `WHERE SALARY LIKE '200%'`  | 查找以 200 开头的任意值             |
+| `WHERE SALARY LIKE '%200'`  | 查找以 200 结尾的任意值             |
+| `WHERE SALARY LIKE '%200%'` | 查找包含 200 的任意值               |
+| `WHERE SALARY LIKE '_00%'`  | 查找第二位是 0，第三位是 0 的任意值 |
+| `WHERE SALARY LIKE '2_%_%'` | 查找以 2 开头且长度至少为 3 的值    |
+| `WHERE SALARY LIKE '2__'`   | 查找以 2 开头且长度为 3 的值        |
+| `WHERE SALARY LIKE '2%5'`   | 查找以 2 开头且以 5 结尾的值        |
+| `WHERE SALARY LIKE '2___5'` | 查找以 2 开头且长度为 5 的值        |