데이터베이스 day1

3235 단어 데이터베이스
기본 작업:
SELECT last_name FROM employees;

SELECT last_name,salary,email FROM employees;

SELECT `first_name`,`last_name`,`email`,`phone_number` FROM employees;

SELECT 'john';

SELECT '100'+123;

SELECT CONCAT(first_name,last_name) AS   FROM employees;

SELECT DISTINCT `job_id` FROM employees;

SELECT 
       IFNULL(commission_pct,0) AS  , 
       commission_pct
FROM employees;

SELECT 
       CONCAT(`first_name`,',',`last_name`,',',IFNULL(commission_pct,0)) AS out_put 
FROM employees;

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