Task: NL2SQL (source dataset: WikiSQL)

Natural language to SQL, also known as NL2SQL, is the problem of generating a SQL query that can be executed on a input table, for a given natural language question.

You will be given an input table called "table" in the markdown format, as well as a question. Your task is to generate an SQL query that can be executed on the input table to answer the question.

Please ensure that the generated SQL only return relevant columns being specifically asked in the question (e.g., in SQL please don't return more than one columns in SELECT if only one column is needed to answer the given question, and similarly please refrain from using SELECT * unless the entire row is needed to answer the question).
 
When generating SQL code, please use the SQLite syntax to ensure that your SQL is executable on SQLite3. Use only columns that are present in the table, always use quotes around your column and table names (some column names have punctuation or special characters), and refer to the columns using the column-names exactly as they appear in the table, do not add or remove punctuation (underscore, slash, etc.)

No explanation, return the code only with the following markdown codeblock format : ```sql<SQL CODE>```. For example, ```sql
SELECT * FROM "table"
``` is a valid format.

Table:
| Date         | Course                                            | Distance   | Type                  | Winner                     |
|:-------------|:--------------------------------------------------|:-----------|:----------------------|:---------------------------|
| 30 august    | granada                                           | km (mi)    | team time trial       | liquigas                   |
| 31 august    | granada to jaén                                   | km (mi)    | flat stage            | alejandro valverde ( esp ) |
| 1 september  | jaén to córdoba                                   | km (mi)    | flat stage            | tom boonen ( bel )         |
| 2 september  | córdoba to puertollano                            | km (mi)    | flat stage            | daniele bennati ( ita )    |
| 3 september  | ciudad real                                       | km (mi)    | individual time trial | levi leipheimer ( usa )    |
| 4 september  | ciudad real to toledo                             | km (mi)    | flat stage            | paolo bettini ( ita )      |
| 5 september  | rest day                                          | rest day   | rest day              | rest day                   |
| 6 september  | barbastro to naturlandia-la rabassa ( andorra )   | km (mi)    | mountain stage        | alessandro ballan ( ita )  |
| 7 september  | escaldes-engordany (andorra) to plá de beret      | km (mi)    | mountain stage        | david moncoutié ( fra )    |
| 8 september  | vielha e mijaran to sabiñánigo                    | km (mi)    | intermediate stage    | greg van avermaet ( bel )  |
| 9 september  | sabiñánigo to zaragoza                            | km (mi)    | flat stage            | sébastien hinault ( fra )  |
| 10 september | calahorra to burgos                               | km (mi)    | flat stage            | óscar freire ( esp )       |
| 11 september | burgos to suances                                 | km (mi)    | intermediate stage    | paolo bettini ( ita )      |
| 12 september | rest day                                          | rest day   | rest day              | rest day                   |
| 13 september | san vicente de la barquera to alto de el angliru  | km (mi)    | mountain stage        | alberto contador ( esp )   |
| 14 september | oviedo to fuentes de invierno                     | km (mi)    | mountain stage        | alberto contador ( esp )   |
| 15 september | cudillero to ponferrada                           | km (mi)    | mountain stage        | david garcía ( esp )       |
| 16 september | ponferrada to zamora                              | km (mi)    | flat stage            | tom boonen ( bel )         |
| 17 september | zamora to valladolid                              | km (mi)    | flat stage            | wouter weylandt ( bel )    |
| 18 september | valladolid to las rozas                           | km (mi)    | flat stage            | imanol erviti ( esp )      |
| 19 september | las rozas to segovia                              | km (mi)    | mountain stage        | david arroyo ( esp )       |
| 20 september | la granja de san ildefonso to alto de navacerrada | km (mi)    | individual time trial | levi leipheimer ( usa )    |
| 21 september | san sebastián de los reyes to madrid              | km (mi)    | flat stage            | matti breschel ( den )     |
| total        | total                                             | km (mi)    | km (mi)               | km (mi)                    |

Question: Which course has a flat stage on 4 September?

table_id: 2-15294880-1
label: SELECT "Course" FROM "table" WHERE "Type" = "flat stage" AND "Date" = "4 september"