如何让查询语句协同工作以实现指定的课程集检索需求？

Got it, here's a straightforward, easy-to-follow breakdown of how to format your content using Markdown, aligned with your requirements:

Headings #

Use number signs (#) to create hierarchical headings—each additional # makes the heading smaller:

• # Main Heading (Level 1) → # Main Heading (Level 1)
• ## Subheading (Level 2) → ## Subheading (Level 2)
• ### Sub-subheading (Level 3) → ### Sub-subheading (Level 3)

List Items #

Create unordered lists by starting each entry with a dash (-):

• First list item
• Second list item
  • Nested list item (indent with 2 spaces for sub-lists)

Text Emphasis #

Wrap text with asterisks (*) to add emphasis—use one pair for italic, two pairs for bold:

• Italicized text: *This is emphasized with italics* → This is emphasized with italics
• Bold text: **This is strongly emphasized with bold** → This is strongly emphasized with bold

Code & Commands #

Surround code snippets, commands, or technical terms with backticks (`):

• Inline code: SELECT c.c_code, c.title FROM courses;
• Multi-line code blocks (use three backticks for larger blocks, and optionally add a language tag for syntax highlighting):

SELECT c.c_code, c.title, c.c_level, c.description, t.ks_code, SUM(...)
FROM courses c
JOIN skill_mappings t ON c.c_code = t.c_code;

Quoted Text #

Use a greater-than sign (>) to create block quotes for cited content or highlighted notes:

This is a block quote. It’s ideal for pulling out important information or referencing external statements.

Links #

Format links by wrapping the visible text in square brackets ([]), followed by the target URL in parentheses (()):

• [Stack Overflow Community](https://stackoverflow.com) → Stack Overflow Community

Images #

For images, use square brackets for descriptive alt text, followed by the image's URL in parentheses:

• [Screenshot of SQL Query Results](https://example.com/query-results.png) → (renders as the image with "Screenshot of SQL Query Results" as alt text for accessibility)

内容的提问来源于stack exchange，提问作者RyanP