英俊的大老虎孤寡孤寡
英俊的大老虎孤寡孤寡
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题解 | #将employees表中的所有员工的last_name和first_name通过引号连接起来。#
SELECT last_name || "'" || first_nameFROM employees/*MySQL代码:SELECT CONCAT(CONCAT(last_name,"'"),first_name)FROM employees*/MySQL不...
2021-07-31
0
376
题解 | #将所有获取奖金的员工当前的薪水增加10%#
UPDATE salaries SET salary=salary*1.1WHERE to_date='9999-01-01' AND emp_no IN ( SELECT emp_no FROM emp_bonus)SET后面跟表达式或常量都可以
2021-07-31
0
290
题解 | #删除emp_no重复的记录,只保留最小的id对应的记录。#
方法1:DELETE FROM titles_testWHERE id IN( SELECT a.mid FROM ( SELECT emp_no,MAX(id) AS mid,COUNT(id) AS num FROM titles_test ...
2021-07-30
0
344
题解 | #构造一个触发器audit_log#
CREATE TRIGGER audit_logAFTER INSERT ON employees_testFOR EACH ROWBEGININSERT INTO audit(EMP_no,NAME) VALUES(NEW.ID,NEW.NAME);END; 注意:不要掉了分号1.create t...
2021-07-30
0
280
题解 | #针对上面的salaries表emp_no字段创建索引idx_emp_no#
1.SQLite写法:SELECT *FROM salariesINDEXED BY idx_emp_noWHERE emp_no='10005' 2.MySQL写法:SELECT *FROM salariesFORCE INDEX (idx_emp_no)WHERE emp_no='10005'
2021-07-30
0
279
题解 | #针对actor表创建视图actor_name_view#
CREATE VIEW actor_name_view(first_name_v,last_name_v)ASSELECT first_name,last_nameFROM actor;/*方法2:CREATE VIEW actor_name_viewASSELECT first_name AS f...
2021-07-30
0
325
题解 | #对first_name创建唯一索引uniq_idx_firstname#
/*ALTER table actor ADD unique uniq_idx_firstname(first_name);注意:SQLite已经不支持ALTER TABLE创建索引功能!*/create UNIQUE index uniq_idx_firstname on actor(first_...
2021-07-30
0
269
题解 | #创建一个actor_name表#
1.建表同时导入(对于MySQL,那么AS可以去掉,也可以不去掉):CREATE TABLE actor_name ASSELECT first_name,last_nameFROM actor2.先建表,然后导入:CREATE TABLE actor_name(first_name varchar...
2021-07-30
0
439
题解 | #批量插入数据,不使用replace操作#
1.如果不存在则插入,如果存在则忽略INSERT OR IGNORE INTO tablename VALUES(...); sqlite3写法:INSERT OR IGNORE INTO actorVALUES(3,'ED','CHASE','2006-02-15 12:34:33'); MySQ...
2021-07-30
0
298
题解 | #批量插入数据#
INSERT INTO actor(actor_id,first_name,last_name,last_update) VALUES (1,'PENELOPE','GUINESS','2006-02-15 12:34:33');INSERT INTO actor(actor_id,first_na...
2021-07-30
0
272
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