document/ddia
2
0
Fork 0
mirror of https://github.com/Vonng/ddia.git synced 2024-12-06 15:20:12 +08:00
Code Issues Packages Projects Releases Wiki Activity

Fix a mathematical environment issue.

Browse Source
This commit is contained in:
Ze Wang 2023-02-16 04:41:37 -05:00 committed by GitHub
parent f9c006a0cf
commit 74eb54e10e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
ch2.md
View File

@ -316,10 +316,12 @@ function getSharks() {
```
在关系代数中：
$$
sharks = σ_{family = "sharks"}(animals)
sharks = \sigma_{family = "sharks"}(animals)
$$
σ（希腊字母西格玛）是选择操作符，只返回符合条件的动物，`family="shark"`。
$\sigma$（希腊字母西格玛）是选择操作符，只返回符合条件的动物，`family="shark"`。
定义 SQL 时，它紧密地遵循关系代数的结构：