freeCodeCamp/guide/chinese/sql/sql-select-distinct-statement/index.md

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SQL Select Distinct Statement	SQL选择Distinct语句

SQL选择Distinct语句

介绍

此关键字允许我们获取列中唯一值的列表。本指南将证明这一点。

完整显示学生表中的数据

USE fcc_sql_guides_database; 
 SELECT studentID, FullName, sat_score, programOfStudy, rcd_Created, rcd_Updated FROM student; 

+-----------+------------------------+-----------+------------------+---------------------+---------------------+ 
 | studentID | FullName               | sat_score | programOfStudy   | rcd_Created         | rcd_Updated         | 
 +-----------+------------------------+-----------+------------------+---------------------+---------------------+ 
 |         1 | Monique Davis          |       400 | Literature       | 2017-08-16 15:34:50 | 2017-08-16 15:34:50 | 
 |         2 | Teri Gutierrez         |       800 | Programming      | 2017-08-16 15:34:50 | 2017-08-16 15:34:50 | 
 |         3 | Spencer Pautier        |      1000 | Programming      | 2017-08-16 15:34:50 | 2017-08-16 15:34:50 | 
 |         4 | Louis Ramsey           |      1200 | Programming      | 2017-08-16 15:34:50 | 2017-08-16 15:34:50 | 
 |         5 | Alvin Greene           |      1200 | Programming      | 2017-08-16 15:34:50 | 2017-08-16 15:34:50 | 
 |         6 | Sophie Freeman         |      1200 | Programming      | 2017-08-16 15:34:50 | 2017-08-16 15:34:50 | 
 |         7 | Edgar Frank "Ted" Codd |      2400 | Computer Science | 2017-08-16 15:35:33 | 2017-08-16 15:35:33 | 
 |         8 | Donald D. Chamberlin   |      2400 | Computer Science | 2017-08-16 15:35:33 | 2017-08-16 15:35:33 | 
 |         9 | Raymond F. Boyce       |      2400 | Computer Science | 2017-08-16 15:35:33 | 2017-08-16 15:35:33 | 
 +-----------+------------------------+-----------+------------------+---------------------+---------------------+ 
 9 rows in set (0.00 sec) 

获取学习领域列表

SELECT DISTINCT programOfStudy FROM student; 

+------------------+ 
 | programOfStudy   | 
 +------------------+ 
 | Literature       | 
 | Programming      | 
 | Computer Science | 
 +------------------+ 
 3 rows in set (0.00 sec) 

与所有这些SQL事物一样，它们比本入门指南中的内容更多。

我希望这至少足以让你开始。

请参阅您的数据库管理员手册，并自己尝试不同的选项。