update:2021

Mysql/mysql基础.md

@@ -155,5 +155,86 @@ where
             is null
             
 */
+#查询工资大于12000的员工
+select 
+	*
+from
+	employees
+where
+	salary>12000;
+
+#查询部门编号不等于90的员工名和部门编号
+select 
+	last_name,department_id
+from
+	employees
+where
+	department_id <> 90;
+
+#查询部门编码不是在90到110之间，或者工资高于15000的员工信息
+select 
+	*
+from
+	employees
+where
+	not (department_id >= 90 and department_id <= 110)
+or 
+	salary >15000;
+
+
+#模糊查询
+# 查询员工名中包含字符a的员工信息
+select
+	*
+from
+	employees
+where
+	last_name like '%a%';
+```
+
+通配符
+
+- % 任意多个字符a的员工
+- _任意单个字符
+
+```mysql
+#查询员工名中第三个字符为n，第五个字符为l的员工名和工资
+select
+	last_name,
+    salary
+from
+	employees
+where
+	last_name like '__n_l%';
+
+#字符转义
+select
+	last_name
+from
+	employees
+where
+	last_name like '_\_%';
+
+#可以指定转义字符
+select
+	last_name
+from
+	employees
+where
+	last_name like '_$_%' escape '$'
+```
+
+between...and..左闭右闭
+
+in(列表)
+
+```mysql
+#in的使用
+select
+	*
+from
+	employees
+where
+	job_id in('AD_PRES','AD_VP');
 ```
 

Mysql/条件查询.sql

@@ -0,0 +1,111 @@
+
+#查询工资大于12000的员工
+select 
+	*
+from
+	employees
+where
+	salary>12000;
+
+#查询部门编号不等于90的员工名和部门编号
+select 
+	last_name,department_id
+from
+	employees
+where
+	department_id <> 90;
+
+#查询部门编码不是在90到110之间，或者工资高于15000的员工信息
+select 
+	*
+from
+	employees
+where
+	not (department_id >= 90 and department_id <= 110)
+or 
+	salary >15000;
+
+
+#模糊查询
+# 查询员工名中包含字符a的员工信息
+select
+	*
+from
+	employees
+where
+	last_name like '%a%';
+
+
+#查询员工名中第三个字符为n，第五个字符为l的员工名和工资
+select
+	last_name,
+    salary
+from
+	employees
+where
+	last_name like '__n_l%';
+
+#字符转义
+select
+	last_name
+from
+	employees
+where
+	last_name like '_\_%';
+
+#可以指定转义字符
+select
+	last_name
+from
+	employees
+where
+	last_name like '_$_%' escape '$';
+
+
+#in的使用
+select
+	*
+from
+	employees
+where
+	job_id in('AD_PRES','AD_VP');
+
+#is null的使用
+select
+	last_name,
+    commission_pct
+from
+	employees
+where
+	commission_pct is null;#这里不能写 = null，没有这种表达式
+
+# 安全等于
+select
+	last_name,
+    commission_pct
+from
+	employees
+where
+	commission_pct <=> null;
+
+# 查询员工号为176的员工的姓名和部门号和年薪
+select 
+	last_name,
+    department_id,
+    salary*12*(1+ifnull(commission_pct,0)) AS 年薪  #这里要注意奖金率可能为null的情况
+from
+	employees;
+
+#查询没有奖金，且工资小于18000的salary，姓名
+select
+	concat(last_name,first_name) as 姓名,salary,commission_pct
+from
+	employees
+where
+	commission_pct is null
+and
+	salary < 18000;
+
+#查询employees表中，job_id
+
+