DML 操作是指對數據庫中表記錄的操作，主要包括表記錄的插入（insert）、更新（update）、刪除（delete）和查詢（select），是開發人員日常使用最頻繁的操作。
插入記錄
表創建好后，就可以往里插入記錄了，插入記錄的基本語法如下
INSERT INTO tablename (field1, field2, .…, fieldn）VALUES (value1, value2, ..……, valuen);
向表 emp 中插入：ename 為 zzx1，hiredate 為 2000-01-01，sal 為 2000，deptno 為 1
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| ename | varchar(10) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| deptno | int(2) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
mysql> insert into emp(ename,hiredate,sal,deptno) values('zzx1','2000-01-01','2000',1);
Query OK, 1 row affected (0.01 sec)
也可以不用指定字段名稱，但是 values 后面的順序應該和字段的排列順序一致
mysql> insert into emp values('lisa','2003-02-01','3000',2);
Query OK, 1 row affected (0.01 sec)
mysql> insert into emp values('bjguan','2004-04-02','4000',1);
Query OK, 1 row affected (0.01 sec)
只對表中的 ename 和 sal 字段顯式插入值
mysql> insert into emp(ename,sal) values('dony',1000);
Query OK, 1 row affected (0.01 sec)
查看實際插入的值
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx1 | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 3000.00 | 2 |
| bjguan | 2004-04-02 | 4000.00 | 1 |
| dony | NULL | 1000.00 | NULL |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
可以一次性插入多條記錄，每條記錄之間用逗號分隔
INSERT INTO tablename (field1, field2, ..…, fieldn)
VALUES
(record1_value1, record1_value2, .…, record1_valuen),
(record2_value1, record2_value2, .…, record2_valuen),
...
(recordn_value1, recordn_value2, .…, recordn_valuen);
首先創建表 dept
mysql> create table dept(deptno int(2), deptname varchar(10));
Query OK, 0 rows affected (0.03 sec)
mysql> desc dept;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| deptno | int(2) | YES | | NULL | |
| deptname | varchar(10) | YES | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
對 dept 表一次插入多條記錄
mysql> insert into dept values(1,'tech'),(2,'sale'),(5,'fin'),(5,'dept5'),(6,'dept6');
Query OK, 5 rows affected (0.01 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tech |
| 2 | sale |
| 5 | fin |
| 5 | dept5 |
| 6 | dept6 |
+--------+----------+
5 rows in set (0.00 sec)
更新記錄
UPDATE tablename SET field1=value1, field2=value2, ..., fieldn=valuen [WHERE CONDITION]
將表 emp 中 ename 為 “lisa” 的薪水（sal）從 3000 改為 4000
mysql> update emp set sal=4000 where ename='lisa';
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx1 | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 4000.00 | 1 |
| dony | NULL | 1000.00 | NULL |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
update 命令可以同時更新多個表中的數據
UPDATE t1, t2, ..., tn set t1.field1=expr1, t2.field2=expr2, ..., tn.fieldn=exprn [WHERE CONDITION]
同時更新表 emp 中的字段 sal 和表 dept 中的字段 deptname
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx1 | 2000-01-01 | 100.00 | 1 |
| lisa | 2003-02-01 | 200.00 | 2 |
| bjguan | 2004-04-02 | 100.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tech |
| 2 | sale |
| 5 | fin |
+--------+----------+
3 rows in set (0.00 sec)
mysql> update emp a, dept b set a.sal=a.sal*b.deptno, b.deptname=a.ename where a.deptno=b.deptno;
Query OK, 3 rows affected (0.01 sec)
Rows matched: 5 Changed: 3 Warnings: 0
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx1 | 2000-01-01 | 100.00 | 1 |
| lisa | 2003-02-01 | 400.00 | 2 |
| bjguan | 2004-04-02 | 100.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | zzx1 |
| 2 | lisa |
| 5 | fin |
+--------+----------+
3 rows in set (0.00 sec)
刪除記錄
DELETE FROM tablename [where CONDITION]
將 emp 中 ename 為 “dony” 的記錄全部刪除
mysql> delete from emp where ename='dony';
Query OK, 1 row affected (0.01 sec)
mysql> select * from emp;
+--------+------------+--------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+--------+--------+
| zzx1 | 2000-01-01 | 100.00 | 1 |
| lisa | 2003-02-01 | 400.00 | 2 |
| bjguan | 2004-04-02 | 100.00 | 1 |
+--------+------------+--------+--------+
3 rows in set (0.00 sec)
可以一次刪除多個表的數據
DELETE t1, t2, ..., tn FROM t1, t2, ..., tn [WHERE CONDITION]
如果 from 后面的表名用別名，則 delete 后面也要用相應的別名，否則會提示語法錯誤
同時刪除表 emp 和 dept 中 deptno 為 3 的記錄
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx1 | 2000-01-01 | 100.00 | 1 |
| lisa | 2003-02-01 | 200.00 | 2 |
| bjguan | 2004-04-02 | 100.00 | 1 |
| bzshen | 2005-04-01 | 300.00 | 3 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
5 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tach |
| 2 | sale |
| 3 | hr |
| 5 | fin |
+--------+----------+
4 rows in set (0.00 sec)
mysql> delete a,b from emp a,dept b where a.deptno=b.deptno and a.deptno=3;
Query OK, 2 rows affected (0.01 sec)
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx1 | 2000-01-01 | 100.00 | 1 |
| lisa | 2003-02-01 | 200.00 | 2 |
| bjguan | 2004-04-02 | 100.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tach |
| 2 | sale |
| 5 | fin |
+--------+----------+
3 rows in set (0.00 sec)
查詢記錄
SELECT * FROM tablename [where CONDITION]
顯示 emp 表中的全部記錄
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
mysql> select ename,hiredate,sal,deptno from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
查詢不重復的記錄
將表中的記錄去掉重復后顯示出來，可以用distinct關鍵字來實現：
mysql> select ename,hiredate,sal,deptno from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
mysql> select distinct deptno from emp;
+--------+
| deptno |
+--------+
| 1 |
| 2 |
+--------+
2 rows in set (0.00 sec)
條件查詢
查詢所有 deptno 為 1 的記錄
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
mysql> select * from emp where deptno=1;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
2 rows in set (0.00 sec)
多字段查詢
mysql> select * from emp where deptno=1 and sal<3000;
+-------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+-------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
+-------+------------+---------+--------+
1 row in set (0.00 sec)
排序和限制
SELECT * FROM tablename [WHERE CONDITION] [ORDER BY field1 [DESC | ASC], field2 [DESC | ASC], ..., fieldn [DESC | ASC]]
DESC：降序排列 ASC：升序排列
把 emp 表中的記錄按照工資高低進行顯示
mysql> select * from emp order by sal;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
如果排序字段的值一樣，則值相同的字段按照第二個排序字段進行排序，依次類推。如果只有一個排序字段，則這些字段相同的記錄將會無序排列。
把 emp 表中的記錄按照部門編號 deptno 字段排序
mysql> select * from emp order by deptno;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
對於 deptno 相同的前兩條記錄，如果要按照工資由高到低排序，可以使用以下命令
mysql> select * from emp order by deptno,sal desc;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| bjguan | 2004-04-02 | 5000.00 | 1 |
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
對於排序后的記錄，如果希望只顯示一部分，而不是全部，這時，就可以使用 LIMIT 關鍵字來實現
SELECT ... [LIMIT offset_start, row_count]
其中 offset_start 表示記錄的起始偏移量，row_count 表示顯示的行數。
在默認情況下，起始偏移量為 0，只需要寫記錄行數就可以，這時，實際顯示的就是前 n 條記錄。例如，顯示 emp 表中按照 sal 排序后的前 3 條記錄：
mysql> select * from emp order by sal limit 3;
+-------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+-------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
| lisa | 2003-02-01 | 4000.00 | 2 |
+-------+------------+---------+--------+
3 rows in set (0.00 sec)
如果要顯示 emp 表中按照 sal 排序后從第二條記錄開始的 3 條記錄，可以使用以下命令：
mysql> select * from emp order by sal limit 1,3;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| dony | 2005-02-05 | 2000.00 | 4 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
聚合
SELECT [field1, field2, ..., fieldn] fun_name
FROM tablename
[WHERE where_contition]
[GROUP BY field1, field2, ..., fieldn
WITH ROLLUP]]
[HAVING where_contition]
參數說明：
- fun_name 表示要做的聚合操作，也就是聚合函數，常用的有
sum（求和）、count（記數）、max（最大值）、min（最小值）、avg（平均值）。 - GROUP BY 關鍵字表示要進行分類聚合的字段，比如要按照部門分類統計員工數量，部門就應該寫在 group by 后面。
- WITH ROLLUP 是可選語法，表明是否對分類聚合后的結果進行再匯總。
- HAVING 關鍵字表示對分類后的結果再進行條件的過濾。
注意：having 和 where 的區別在於，having 是對聚合后的結果進行條件的過濾，而 where 是在聚合前就對記錄進行過濾，如果邏輯允許，盡可能用 where 先過濾記錄，這樣因為結果集減小，將對聚合的效率大大提高，最后再根據邏輯看是否用 having 進行再過濾。
在 emp 表中統計公司人數
mysql> select count(1) from emp;
+----------+
| count(1) |
+----------+
| 4 |
+----------+
1 row in set (0.00 sec)
在此基礎上，要統計各個部門的人數
mysql> select deptno,count(1) from emp group by deptno;
+--------+----------+
| deptno | count(1) |
+--------+----------+
| 1 | 2 |
| 2 | 1 |
| 4 | 1 |
+--------+----------+
3 rows in set (0.00 sec)
更詳細一些，既要統計部門人數，又要統計總人數
mysql> select deptno,count(1) from emp group by deptno with rollup;
+--------+----------+
| deptno | count(1) |
+--------+----------+
| 1 | 2 |
| 2 | 1 |
| 4 | 1 |
| NULL | 4 |
+--------+----------+
4 rows in set (0.00 sec)
統計人數大於 1 的部門
mysql> select deptno,count(1) from emp group by deptno having count(1)>1;
+--------+----------+
| deptno | count(1) |
+--------+----------+
| 1 | 2 |
+--------+----------+
1 row in set (0.00 sec)
統計公司所有員工薪水總額、最高和最低薪水
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select sum(sal),max(sal),min(sal) from emp;
+----------+----------+----------+
| sum(sal) | max(sal) | min(sal) |
+----------+----------+----------+
| 13000.00 | 5000.00 | 2000.00 |
+----------+----------+----------+
1 row in set (0.00 sec)
表連接
當需要同時顯示多個表中的字段時，就可以用表連接來實現這樣的功能。從大類上分，表連接分為內連接和外連接，它們之間的最主要區別是，內連接僅選出兩張表中互相匹配的記錄，而外連接會選出其他不匹配的記錄。常用的是內連接。
查詢出所有雇員的名字和所在部門名稱，因為雇員名稱和部門分別存放在表 emp 和 dept 中，因此，需要使用表連接來進行查詢
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tach |
| 2 | sale |
| 5 | fin |
+--------+----------+
3 rows in set (0.01 sec)
mysql> select ename,deptname from emp,dept where emp.deptno=dept.deptno;
+--------+----------+
| ename | deptname |
+--------+----------+
| zzx | tach |
| bjguan | tach |
| lisa | sale |
+--------+----------+
3 rows in set (0.00 sec)
外連接又分為左連接和右連接：
- 左連接：包含所有的左邊表中的記錄甚至是右邊表中沒有和它匹配的記錄。
- 右連接：包含所有的右邊表中的記錄甚至是左邊表中沒有和它匹配的記錄。
查詢 emp 中所有用戶名和所在部門名稱
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tach |
| 2 | sale |
| 5 | fin |
+--------+----------+
3 rows in set (0.00 sec)
mysql> select ename,deptname from emp left join dept on emp.deptno=dept.deptno;
+--------+----------+
| ename | deptname |
+--------+----------+
| zzx | tach |
| bjguan | tach |
| lisa | sale |
| dony | NULL |
+--------+----------+
4 rows in set (0.00 sec)
右連接和左連接類似，兩者之間可以互相轉化，上面的例子可以改寫為如下的右連接
mysql> select ename,deptname from dept right join emp on dept.deptno=emp.deptno;
+--------+----------+
| ename | deptname |
+--------+----------+
| zzx | tach |
| bjguan | tach |
| lisa | sale |
| dony | NULL |
+--------+----------+
4 rows in set (0.00 sec)
子查詢
某些情況下，當進行查詢的時候，需要的條件是另外一個 select 語句的結果，這個時候，就要用到子查詢。用於子查詢的關鍵字主要包括 in、not in、=、!=、exists、not exists 等。
從 emp 表中查詢出所有部門在 dept 表中的所有記錄
mysql> select * from emp
-> where deptno
-> in(select deptno from dept);
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
如果子查詢記錄數唯一，還可以用 = 代替 in
mysql> select * from emp
-> where deptno = (select deptno from dept);
ERROR 1242 (21000): Subquery returns more than 1 row
mysql> select * from emp
-> where deptno = (select deptno from dept limit 1);
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
+--------+------------+---------+--------+
2 rows in set (0.00 sec)
某些情況下，子查詢可以轉化為表連接
mysql> select * from emp where deptno in(select deptno from dept);
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
mysql> select emp.* from emp, dept where emp.deptno=dept.deptno;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
+--------+------------+---------+--------+
3 rows in set (0.00 sec)
注意：子查詢和表連接之間的轉換主要應用在兩個方面。
- MySQL 4.1 以前的版本不支持子查詢，需要用表連接來實現子查詢的功能.
- 表連接在很多情況下用於優化子查詢。
記錄聯合
將兩個表的數據按照一定的查詢條件查詢出來后，將結果合並到一起顯示出來，這個時候，就需要用 union 和 union all 關鍵字來實現這樣的功能
SELECT * FROM t1
UNION | UNION ALL
SELECT * FROM t2
...
UNION | UNION ALL
SELECT * FROM tn;
UNION 和 UNION ALL 的主要區別是 UNION ALL 是把結果集直接合並在一起，而 UNION 是將 UNION ALL 后的結果進行一次 DISTINCT，去除重復記錄后的結果。
將 emp 和 dept 表中的部門編號的集合顯示出來
mysql> select * from emp;
+--------+------------+---------+--------+
| ename | hiredate | sal | deptno |
+--------+------------+---------+--------+
| zzx | 2000-01-01 | 2000.00 | 1 |
| lisa | 2003-02-01 | 4000.00 | 2 |
| bjguan | 2004-04-02 | 5000.00 | 1 |
| dony | 2005-02-05 | 2000.00 | 4 |
+--------+------------+---------+--------+
4 rows in set (0.00 sec)
mysql> select * from dept;
+--------+----------+
| deptno | deptname |
+--------+----------+
| 1 | tach |
| 2 | sale |
| 5 | fin |
+--------+----------+
3 rows in set (0.00 sec)
mysql> select deptno from emp
-> union all
-> select deptno from dept;
+--------+
| deptno |
+--------+
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2 |
| 5 |
+--------+
7 rows in set (0.00 sec)
將結果去掉重復記錄后顯示如下
mysql> select deptno from emp
-> union
-> select deptno from dept;
+--------+
| deptno |
+--------+
| 1 |
| 2 |
| 4 |
| 5 |
+--------+
4 rows in set (0.00 sec)