SQLDistinct语句

SQL DISTINCT 关键字与SELECT语句结合使用，以消除所有重复记录并仅获取唯一记录。

Distinct - 语法

消除重复记录的DISTINCT关键字的基本语法如下-

SELECT DISTINCT column1, column2,.....columnN 
FROM table_name
WHERE [condition]

Distinct- 示例

考虑具有以下记录的CUSTOMERS表-

+----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  6 | Komal    |  22 | MP        |  4500.00 |
|  7 | Learnfk    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+

首先，让无涯教程看看下面的SELECT查询如何返回重复的薪水记录。

SQL> SELECT SALARY FROM CUSTOMERS
   ORDER BY SALARY;

+----------+
| SALARY   |
+----------+
|  1500.00 |
|  2000.00 |
|  2000.00 |
|  4500.00 |
|  6500.00 |
|  8500.00 |
| 10000.00 |
+----------+

现在，让无涯教程在上面的SELECT查询中使用DISTINCT关键字，然后查看输出。

SQL> SELECT DISTINCT SALARY FROM CUSTOMERS
   ORDER BY SALARY;

如果没有任何重复的条目，这将产生以下输出。

+----------+
| SALARY   |
+----------+
|  1500.00 |
|  2000.00 |
|  4500.00 |
|  6500.00 |
|  8500.00 |
| 10000.00 |
+----------+