From de4844ecad77be25ad1a3e54bfea6eee4798a3a6 Mon Sep 17 00:00:00 2001
From: smallkun <smallerkun@foxmail.com>
Date: Fri, 28 Feb 2025 11:29:41 +0800
Subject: [PATCH] Auto commit
---
2208/天天乐学考试答案/MySQL练习（一）.md | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/2208/天天乐学考试答案/MySQL练习（一）.md b/2208/天天乐学考试答案/MySQL练习（一）.md
index 073d2b7..bdf0eef 100644
--- a/2208/天天乐学考试答案/MySQL练习（一）.md
+++ b/2208/天天乐学考试答案/MySQL练习（一）.md
@@ -302,3 +302,25 @@ END $$
DELIMITER ;
```
+### 第四套
+
+```sql
+#1
+ALTER TABLE tb_students MODIFY gender ENUM('男', '女', '未知');
+#2
+ALTER TABLE tb_scores MODIFY score FLOAT(7, 2);
+#3
+CREATE TABLE tb_scores_bak1 AS
+SELECT *
+FROM tb_scores;
+#4
+UPDATE test1 t1, (
+ SELECT tname, CONCAT(tname,'@',COUNT(*)) str
+ FROM test1
+ GROUP BY tname
+ HAVING COUNT(*) IN (3, 4)
+)t2
+SET t1.tname = t2.str
+WHERE t1.tname = t2.tname;
+```
+