一、普通查询

select * from STUselect * from stu where ROWNUM<=3 select * from stu where stu_id like 'stu001%'

说明：通配符“%”代表一个或者多个字符，通配符“_”代表一个字符。

select STU_ID as 学号 from stu

二、联合查询

SELECT STU.STU_NAME, STU.STU_AGE, KC.KC_NAME FROM STU, KC WHERE STU.KC_NO = KC.KC_NOSELECT STU.STU_NAME, STU.STU_AGE, KC.KC_NAME FROM STU INNER JOIN KC ON STU.KC_NO = KC.KC_NO ORDER BY STU.STU_ID SELECT STU.STU_NAME, STU.STU_AGE, KC.KC_NAME FROM STU LEFT JOIN KC ON STU.KC_NO = KC.KC_NO ORDER BY STU.STU_ID SELECT STU.STU_NAME, STU.STU_AGE, KC.KC_NAME FROM STU RIGHT JOIN KC ON STU.KC_NO = KC.KC_NO ORDER BY STU.STU_ID SELECT STU.STU_NAME, STU.STU_AGE, KC.KC_NAME FROM STU FULL JOIN KC ON STU.KC_NO = KC.KC_NO ORDER BY STU.STU_ID SELECT STU_NAME FROM STU UNION SELECT KC_NAME FROM KC