chore: update tag from 'mysql' to 'database' for database posts

Author: eottabom

posts/database/mysql-validation-errors.mdx

@@ -1,7 +1,7 @@
 ---
 title: "MySQL Value '0000-00-00' can not be represented as java.sql.Date errors"
 date: "2020-05-17"
-tags: ["MySQL"]
+tags: ["Database"]
 summary: "MySQL Validation errors Cause and Workaround"
 description: "MySQL Validation errors 원인과 해결 방법"
 ---