myemployeesを使用します.sqlはsql言語の条件クエリーを行う

#   2：    
/*
  ： 
     select
               
     from  
             
     where 
               ;
    ：
       、        
           ：> < = !=  <> <= >=
       、        
           ：&& || !
                  and or not
       、    
               like
               between and
               in
               is null
 */
 
#  、        
 
#  1：    >12000     
SELECT
      *
FROM
      employees
WHERE 
      salary>12000;
      
#  2：          90         
SELECT last_name, department_id 
FROM employees 
WHERE department_id <>90;

#  、        
#  1：     10000 20000      、      
SELECT last_name,salary,commission_pct		
FROM employees;
WHERE salary>=10000 AND salary<=20000;

# 、    
#1.like            %      ，  0   _       
#  1：          a     
SELECT *
FROM employees
WHERE last_name LIKE '%a%';
#   2：            e，      a    
SELECT last_name,salary
FROM employees
WHERE last_name LIKE '__e_a%';

#  3：            _    
SELECT last_name
FROM employees
WHERE last_name LIKE '_\_%';

#2.between and      ，    

#  1：       100 120       
SELECT *
FROM employees
WHERE employee_id BETWEEN 100 AND 120;

#3. in 
#  ：          IT_PROG、AD_VP、AD_PRES            
SELECT last_name, job_id
FROM employees
WHERE job_id IN ('IT_PROG','AD_VP','AD_PRES');

#4. is null   = <>    null
#  1：              
SELECT last_name,commission_pct
FROM employees
WHERE commission_pct IS NULL;


#     <=>
#  1：              
SELECT last_name,commission_pct
FROM employees
WHERE commission_pct <=> NULL;

#  12：     12000     
SELECT
      *
FROM
      employees
WHERE 
      salary <=> 12000;